ISODC, IIT Kharagpur Team, May 2008

IIT Kharagpur, May 2008

DESIGN OF FPSO FOR USAN FIELD, NIGERIA

Submitted By:-

ASHISH KUMAR JHA

GYANENDU SAHOO

PRABHAKAR TIWARI

SAURABH SINGH

VIVEK GUPTA

Department of Ocean Engineering and Naval Architecture

Indian Institute of Technology, Kharagpur-721302, India


CONTENTS

LIST OF IMPORTANT TABLES……………………………...………………………………………………..….4

LIST OF FIGURES…………………………………………………………………………………………….…….5

EXECUTIVE SUMMARY…………………………………………………………………………………......……6

INTRODUCTION………………………………………………………………………………………………..….11

COMPETANCY AREAS……………………………………………………………………………………….…..18

1. GENERAL ARRANGEMENT & HULL DESIGN…………………………………….………….……18

1.1 Preliminary Analysis……………………………………………………………………....……………18

1.2 Checking against ILLC regulations………………………………………………………………….….21

1.3 Checking against MARPOL 73/78 Regulations……………………………………………………..…22

1.4Frame Spacing………………………………………………………………………………………...…22

1.5 Slop Tanks and Fuel Oil tanks …………………………………………...………………………….….22

1.6Crude Oil Tanks and Compartments definitions…………………………..……………………….……23

1.7 Engine Room Layout…………………………………………………………………………………....25

1.8Accommodation Layout…………………………………………….…………………………………...29

1.9Topsides……………………………………………………………….……...……………………….…38

2. WEIGHT, BUOYANCY AND STABILITY…………………………………………………………..…41 2.1 Weight and Buoyancy …………………………………………………….………………………….…41

2.2 Stability Considerations………………………………………………………..…………………...…...46

2.2.1 Intact Stability……………………………………………………..…………………..…….47

2.2.2 Damage Stability…………………………………………………….……………………....49

2.2.3 Probabilistic Damage Assessment…………………………………...…………………..52

3. WIND AND CURRENT LOADING…………………………………………………………………..…57

3.1 Wind Force Calculations……………………………………………………….……………………….57

3.2 Current Force Calculations……………………………………………………………………………..58

3.3 Steady Wave Loads………………………………………………………………………………….…59

3.4 Net Environmental Loads……………………………………………………...……………………….60

4. STRENGTH AND STRUCTURAL DESIGN – GENERAL…………………………………….……..61

4.1 Work Flow…………………………………………………………………………………………..….62

4.2 Load Calculations………………………………………………………………………………………63

4.3 Results…………………………………………………………………………………………………..65

4.4 Structural Components…………………………………………………………………………….……65

4.5 Final Analysis…………………………………………………………………………………….…..…70

5. MOORING AND STATION KEEPING…………………………………………..………………….….72

5.1 Design Environmental Criteria………………………………………………………………….…...….72

5.2 Vessel Design Characteristics……………………………………………………………………..…….73

5.3 Vessel Offsets and Design Pretensions………………………………………………………….…...….74

5.4 Analytical Procedure………………………………………………………………………….….……..75

5.5 Mooring Line Configuration…………………………………………….………………………………75

5.6 Mooring System Evaluation…………………………………………………….………………………75

5.6.1 Environmental Loads……………………………………………..…………………………75

5.6.2 Mooring System Design…………………………………………...……………………..….76

5.7 Anchoring System………………………………………………………………………………...…….77

5.7.1 Anchor Design…………………………………………………...……………………….….78

5.8 Turret Concept…………………………………………………………………….………………….…79

5.8.1 Function of a Turret System…………………………………………..……………...……..80


5.8.2 Weathervaning………………………………………………………..……………………..81

5.8.3 Parts of a Turret system………………………………………..……………………..……..81

5.8.4 Interfaces……………………………………………………………...………….………….82

5.8.5 Load Transfer for a Turret System…………………………..………………………………82

6. POWER GENERATION, DISTRIBUTION AND ELECTRIC LOAD ANALYSIS…………………….83

6.1Calculation of various load cases……………………………………………………………………..…84 6.2 Power Estimation for Production Modules…………………………………...………………………....86 6.3 Selection of TPPL (Total Plant Peak Load)……………………………………………………...………88 6.4 Selection of Power Plant……………………………………………………………………...……….…89 6.5 Use of Heat Recovery System……………………………………………………………...……………89 6.6 Power Plant Calculations…………………………………………………………………...………..…..90

7. RISK ASSESSMENT …………………………………………………………………..………………....100 7.1 Leak of Gas and/or Oil…………………………………………………………………………...……101 7.2 Non process Incident…………………………………………………………………….………….…102 7.3 Marine Events……………………………………………………………………………….………....103 7.4 Hazards due to Shuttle Tanker Operations……………………………………………….………..…..105

7.4.1 Approaching and Berthing………………………………………………..……..…………105 7.4.2 Connection of Shuttle Tanker with FPSO………………………………...………………..106 7.4.3 Unberthing and Departure…………………………………………...……………………..107

7.5 Risk Evaluation……………………………………………………………………….………..………108 7.6 Escape Route…………………………………………………………………………………………..109 8. CONSTRUCTION, FABRICATION AND INSTALLATION…………………………………...…….109 8.1 Activities in FPSO Construction……………………………………………………………………....110 8.2 FPSO Construction Process…………………………………………………………………………...110 8.3 Block Distribution of FPSO………………………………………………………………….………..111 8.4 Construction Strategy………………………………………………………………………….…...….113 8.5 Block Fabrication…………………………………………………………………………….……...…114 8.6 Engine Room Construction……………………………………………………………….…………....117 8.7 Welding Details………………………………………………………………………….………….…118 8.8 Outfitting……………………………………………………………………………….………...…….119 8.9 Topside Modules Installation………………………………………………………………………....119 8.10 Installation of FPSO…………………………………………………………………………….……120 9. DECOMMISSIONING AND DISMANTLING…………………………………………………………..120 9.1 Requirements for Recycling………………………………………………………………….……..…121

9.1.1 Risers……………………………………………………………………………………….…121 9.1.2Turret Re-utilization…………………………………………………………..……………….122 9.1.3 Subsea Systems……………………………………………………………….…………...…..123 9.2 Dismantling (Ship Breaking)………………………………………................................……………..123 9.3 Conclusion……………………………………………………………………………….………….…124 References…………………………………………………………………………………….……………………..125 APPENDIX………………………………………………………………………………………………………….126 APPENDIX I………………………………………………………………………………………………………...127 APPENDIX II……………………………………………………………………………………………………….131 APPENDIX III…………………………………………………………………………………..…………………..204 APPENDIX IV………………………………………………………………………………………..……………..215 APPENDIX V……………………………………………………………………………………………………….240 APPENDIX VI………………………………………………………………………………………...…………….251 APPENDIX VII……………………………………………………………………………………………..………268


LIST OF IMPORTANT TABLES

1.1 ABS requirements for Accommodation………………………………….………………………………………30

1.2 Topsides Definitions…………………………………………………………………….……………………….39

2.1 Final weight chart of Power plant……………………………………………………………………..…………42

2.2 Weight and CG of topside modules……………………………………………………………………….……..43

2.3 Weight of cargo tanks…………………………………………………………………………………...……….44

2.4 Weight of slop tanks………………………………………………………………………………………..……45

2.5 Weight of fresh water tanks……………………………………………………………………………………...45

2.6 Weight of MDO tanks…………………………………………………………………………………..……….45

2.7 Calculation of various drafts of FPSO…………………………………………………………………………..46

2.8 Offloading schedule when FPSO is full…………………………………………………………………………48

2.9 Day 6 type offloading schedule…………………………………………………………...…….………………49

2.10 Day 11 type offloading schedule………………………………………………………………….……………49

2.11 Extent of side damage…………………………………………………………………….….…………………50

2.12 Volume of wing and centre cargo tanks…………………………………………..……………….……………51

2.13 Damage cases Analysis……………………………………………………………….…………..……………52

2.14 Calculation of S1………………………………………………………………………….…………………….55

2.15 Calculation of S2………………………………………………………………………………………………..56

2.16 Calculation of S12……………………………………………………………………………………………….56

2.17 Calculation of PiSi…………………………………………………………………………………..…………..56

3.1 Dimension and extreme drafts……………………………………………………………………..…………….57

3.2 Wind force results for extreme drafts……………………………………………………………………………58

3.3 Current force results for extreme drafts……………………………………………………………….…………59

4.1 Horizontal Wave bending moment………………………………………………………………………………64

4.2 Wave bending moment from 100 yr data…………………………………………………………..……………65

4.3 Design bending moment…………………………………………………………………………………………65

4.4 Final Scantlings……………………………………………………………………………………………..……71

5.1 British Standard-6349 anchor system efficiencies……………………………………….………………………78

5.2 Comparison among 3 types of turret systems……………………………………………………………………80

6.1 Efficiency data of motor…………………………………………………………………………………………85

6.2 Factors determining size of pump………………………………………………………….…………….………87

6.3 Selection of Total Plant peak load…………………………………………………………….…………………88

6.4 Rated power of engine………………………………………………………………………...…………………92

6.5 Engine dimensions…………………………………………………………………..………………..….………92

7.1 Risk matrix………………………………………………………………………………………………...……100

7.2 Risk assessment of Leak of oil and gas…………………………………………………………………………102

7.3 Risk assessment of Non Process Incident………………………………………………………………………103

7.4 Risk assessment for marine event hazards…………………………………………...…………………………105

7.5 Hazards due to approaching and berthing………………………………………………………………………106

7.6 Hazards due to connection of shuttle tanker with FPSO…………………………………..……………………107

7.7 Risk evaluation…………………………………………………………………………………………….……108

8.1 Block in cargo hold……………………………………………………………………………..………………113

8.2 Block in engine room…………………………………………………………………………………...………113

8.3 Problem due to part fabrication…………………………………………………………………………………115

8.4 Welding processes………………………………………………………………………………………………119


LIST OF FIGURES

1.1 Profile and Plan View……………………………………………………….……………………………………18

1.2 Preliminary Estimate of Dimensions……………………………………………………………..………………19

1.3Estimation of Fuel and Slop Tank volumes………………………………………………….……………………23

1.4 Cargo and Ballast Tanks……………………………………………………………………………….…………24

1.5 Frames where Bulkheads are located……………………………………………………………….……………24

1.6 Engine Room layout : Elevation……………………………………………………………………….…………25

1.7 Engine Room layout : Plan: Level 0…………………………………………………………………...…………26

1.8 Engine Room layout : Plan: Level 1…………………………………………………………...…………………27

1.9 Engine Room layout : Plan: Level 2…………………………………………………………...…………………28

1.10 Plan of Living Quarters………………………………………………………….………………………………31

1.11 Plan of Helideck…………………………………………………………………………………………………31

1.12 Isometric view of Accommodation…………………………………………………………………...…………32

1.13 Plan of Floor 1…………………………………………………………………………………..………………33

1.14 Plan of Floor 2 and 5………………………………………………………………………….…………………34

1.15 Plan of Floor 3 and 6……………………………………………………………………………….……………35

1.16 Plan of Floor 4…………………………………………………………………………………………..………36

1.17 Plan Floor 7(for Officers) ………………………………………………………………………………………37

1.18 Topsides : Plan View……………………………………………………………………………………………40

2.1 The US Navy criteria………………………………………………………………………………..……………47

2.2 Equivalent Cross Sectional View…………………………………………………………………………………53

3.1 Added Resistance RAO for full load case………………………………………………………………..………59

3.2 Added Resistance RAO for ballast load case………………………………………………………….…………60

4.1 Wave Form ………………………………………………………………………………………….……………62

4.2 Midship section………………………………………………………………………………….………..………71

5.1 Major Oil Producing Areas Worldwide………………………………………………….………………….……72

5.2 Mooring Analysis Flow Chart…………………………………………………………………….………………74

5.3 Deep Water Mooring Line Configuration………………………………………………………………...………75

5.4 Generic Subsystem within a typical mooring system………………………………….…………………………80

5.5 Schematic Diagram showing the interfaces for an FPSO turret…………………………………………….……81

6.1 A Centrifugal Pump………………………………………………………………………...……………….……84

6.2 The diagram showing entire on field processing……………………………………………...….………………87

6.3 FPSO prime mover electrical net efficiencies at various loads………………………………….……..…………91

6.4 FPSO prime mover de-rating at various ambient temperatures……………………………………..……………91

6.5 The dimensions of Engine…………………………………………………………………..….…………………93

6.6 Essential Generator……………………………………………………………………………………….………97

6.7 Emergency Generator……………………………………………………………………………….……………98

6.8 Power Distribution……………………………………………………………………………………..…………99

8.1 Main Activities in FPSO Construction……………………………………………………….…………………110

8.2 Group Technology for Advanced Shipbuilding…………………………………………………………………111

8.3 Block Construction of FPSO…………………………………………………………………………….………112

8.4 Construction Strategy…………………………………………………………………………...……….………113

8.5 Sub Block Assembly…………………………………………………………………………...…………..……115

8.6 Flat Panel……………………………………………………………………………………….……..…………116

8.7 Block Assembly………………………………………………………………………………..………..………117

8.8 Engine Room Construction………………………………………………………………………...……………118

8.9 Matching the Frame Spacing of two structures…………………………………….…………………...………119

9.1 Major ship breaking Tasks (taken from www.osha.gov) ……………………………….………………………124


EXECUTIVE SUMMARY

OWNER’S REQUIREMENTS

The USAN field located 110km off the coast of Nigeria has to be developed for commercial production of

crude oil which is capable of producing up to 200,000 bbls/d. The owner is not interested in laying a

pipeline to the shore as the crude oil produced will be directly supplied to the consumer refineries. The

structure must be able to store 2 million barrels of oil at production site. The owner wants the offshore

structure to be compliant with the rules of the day and is also interested in proper decommissioning of the

structure due to ever increasing environmental concerns. The crew on the structure must be provided all

the comforts possible to increase their efficiency. The owner has already consulted geologists. The

structure will vary out production through 35 riser lines (20 producer and 15 injectors). The owner does

not mention any specific offshore structure to be installed for the project and leaves the decision on the

design team.

OFFSHORE STRUCTURE SELECTED AND CHRIESTENING

FPSO (Floating, production, Storage, Offloading System) was selected as the first choice for the field.

The dimensions L=305.2m, B=56.52m, D=29.8m, T=22m. The topside of the FPSO has following

processing capacity: Oil storage: 2,000,000 bbls , Oil Production: 200,000bbls/d, Liquids treatment:

300,000b/d, Produced water treatment: 180,000b/d, Water Injection: 390,000b/d at 150 bar, Seawater

Sulfate Removal : 400,000b/d ,Gas injection: 8,000,000Sm3/d at 285 bar. The FPSO will be christened as

‘Azikiwe’.

Regulations and guidelines followed:

• ILLC (International Load Line Convention)

• ABS rule for building and classing steel hull vessels (double hull tankers)


• MARPOL Regulations

• SOLAS Regulations(1974) on Damage stability

• ABS rules and guidelines for Crew Habitability on Ships

• API( American Petroleum Institute) in Mooring Design

• US NAVY Criteria to check intact and damage stability.

GENERAL ARRANGEMENT & HULL DESIGN

The general arrangement consisted of hull form design, tank distributions, accommodation, topside

arrangement, engine room design, and escape route. The general arrangement had to be done taking into

account restrictions imposed by regulatory guidelines (MARPOL, SOLAS), classification society (ABS)

and restrictions imposed by other competency areas. Like, the cargo tanks had to sized taking into account

MARPOL and SOLAS regulations at the same time they were supposed to begin and end on transverse

frames of the FPSO and satisfy the cargo capacity requirements (2,000,000bbls), ballast requirements and

slop capacity requirements(14000m3).

WEIGHT, BUOYANCY AND STABILITY

The weight of the FPSO was divided into the following components: (a) Hull Weight (26972 tonnes)),(b)

Weight of the Topside Modules(28,393 tonnes), (c) Accommodation Weight(1873tonnes),(d) Power Plant

Weight(2542.38) tonnes. The US Navy Criteria was used to check both intact static and intact dynamic

stability and also the damage stability. The intact stability was checked during offloading, when the free

surface effect was maximum and the vessel was expected to least stable. During the offloading it was

assumed that the production was still taking place, as well as the dehydration of produced crude was

taking place. For damage stability regulations of MARPOL were followed. Thirteen damage cases were

made, by assuming adjacent two sets of tanks damaged. The stability was checked by both deterministic

method and probabilistic assessment. The effects of free surface due to tanks in topside processing

modules were neglected due to non availability of data.


WIND AND CURRENT LOADING

The Wind and Current Loads were calculated for the 100 year wave, data taken from the Wave Atlas, for

the production field. The environmental force calculations were done for 2 extreme load cases: (1) Full

load case (draft =22m), (2) Ballast load case (draft =7.895m). The wind and current velocity were taken

to be constant with time. The wind and current forces in Full load case were estimated as 1262.7 kN and

2953.466 kN and the same were estimated for ballast case as 1780.814 kN and 1205.893 kN. The steady

wave force was calculated by the added resistance of the FPSO in waves for both the Full and Ballast load

cases. The net force, maximum out of these 2 cases, was accepted as the design environmental force for

FPSO.

STRENGTH AND STRUCTURAL DESIGN - GENERAL

The FPSO was modeled in hydromax for the calculation of bending moments. The design wave for the

FPSO was considered to be of wavelength equal to length of the FPSO and wave height equal to H1/10

(6.36m) taken from the 100 year wave spectrum for USAN field site with Hs(5m). The design bending

moment was found to be 22.80!106 kN-m. The ABS rules for building and classing steel hull vessels

(double hull tankers) were used to determine the midship section.

MOORING AND STATION KEEPING

We have accepted the Turret concept for Single Point Mooring of our facility to enable it for weather

vaning. The Design environmental force was used to design the mooring system for our facility. The

mooring system design consisted of the configuration of mooring line for water depth 850 m (a

combination of chain from fairlead to some distance, then wire rope in the middle and finally the chain up

to the anchor point) , the selection of material of mooring line (chain and wire rope, type and

configuration), determination of tension in the mooring line, the safety factor for the operation and finally

the anchoring system design (anchor weight, holding capacity and efficiency). The 3 possible


configurations of mooring line ( one is only chain and other being the 2 different combinations of chain

and wire rope) were assumed and analyzed for total working tension and then the decision was made for

the best suitable combination on the basis of least self weight of mooring line and least working tension.

API and IACS guidelines were followed.

POWER GENERATION, DISTRIBUTION AND ELECTRIC LOAD ANALYSIS

The power requirements of various systems of the FPSO were calculated and the TPPL ( Total Plant Peak

Load= 56887 Kw). The systems or components whose power requirement could not be directly calculated

were extrapolated from data of FPSO available taking processing capacity as reference. The power plant

was selected on the basis of ‘N-1’ principle where the power plant should be capable of supporting the

electrical load with ‘N-1’ generators and in case of failure of a generator should be able to support the

supply with ‘N-2’ generators until the spare one is started. The FPSO also has a heat recovery system

installed to minimize consumption of fuel. The dual fuel medium speed engine (5 x 18V50DF) was

selected as prime movers for the generators. The FPSO has an ‘essential generator’ (7L32) with 3360 Kw

output and an ‘emergency generator’ (6L26) with 1960Kw output.

RISK ASSESSMENT

Risk assessment is done qualitatively for the various operations in the FPSO. Shuttle tanker interaction

with the FSPO is considered to be the most important operation w.r.t. the hazards associated with it hence

considered separately. Risk level for each event is found on the basis of frequency and consequences

associated with it and accident cause and prevention or mitigation method is given to prevent the

occurrence or to escalation of hazard. Brief description of escape route is given for the evacuation of the

personal in case of any hazard of total loss of FPSO.

CONSTRUCTION, FABRICATION AND INSTALLATION

Construction of FPSO is done by dividing the hull into (11+2) Grand blocks and then further subdivided

into 2 blocks for each Grand block. Gantry crane used for assembly of Grand blocks is of capacity 1200


tonnes. As our FPSO consist of large quantity of flats panels so we introduce group technology for mass

production of flat panels and blocks. Details of the outfitting, welding and production process are

provided for the smooth production process. Installation of modules is done for two types of modules,

custom made and second hand modules, and procedure for installation of FPSO at USAN field is briefly

explained.

DECOMMISSIONING AND DISMANTLING

The need to include the decommissioning and dismantling was felt due to ever increasing environmental

safety concerns. The FPSO should be such that it does not pollute the environment during its life time and

at the time of decommissioning. All the systems of the FPSO should be recovered and no mal practice

should be allowed. The construction should be such that removal of toxic gases and fumes is easier at the

time of dismantling. At the time of decommissioning and dismantling all the international and local rules

must be taken into account. The safety of workers should be a top priority and the owner should ensure

that FPSO is dismantled in a breaking yard which complies with international regulation and respects the

international labor laws and local regulations. Ship breaking is an area where the owners must rise against

profiteering in favor of right of workers in third world countries.


INTRODUCTION

Conditions in Nigeria

Nigeria's proven oil reserves are estimated to be 36 billion barrels; natural gas reserves are well

over 100 trillion cubic feet. Nigeria is a member of the Organization of Petroleum Exporting

Countries (OPEC), and in 2006 its crude oil production averaged around two million barrels per

day. Poor corporate relations with indigenous communities, vandalism of oil infrastructure,

severe ecological damage, and personal security problems throughout the Niger Delta oil-

producing region continue to plague Nigeria's oil sector. Efforts are underway to reverse these

troubles. Although, the FPSO will remain away from the potentially dangerous areas of Nigeria,

it is very important for the operator to take the people and government of Nigeria into confidence

before starting any operations.

There are about 120 languages spoken in Nigeria. The main ethnic groups are the Yorubas,

Hausar-Fulani and the Igbos, none of whom constitute a majority of the population. The naming

of project should be such that it does not offend anyone in Nigeria. So, the project will be named

‘Azikiwe’, after Benjamin Nnamdi Azikiwe (November 16, 1904 – May 11, 1996), the founder

of modern Nigerian nationalism and the first President of Nigeria.

Oilfield

The USAN field located 110 Km from the coast of Nigeia, is result of successful exploration

during 2000-2005. The industry expects the field to be developed by 2010. The peak production

of the field is expected to be 200,000kboe/d. The operating depth is 850m. The oilfield is

expected to be economically viable for at least 20 years.

Figure showing location of USAN field.


Onsite Environmental Conditions

A wave height of a 100-year return period is used design criterion, which was extended by

employing the combination of the 100-year wave with the 100-year wind data. The data shown

below has been taken from ‘World Wave Atlas’.

100 year Wave data Specific Wave height = 5.00 m Wave Period = 12 sec

100 year wind data Wind speed = 12 m/s 100 year current data Current speed = 1.33 m/s

Selection of the Offshore Structure

Sl. No. Offshore Structure Type Operational Depth 1. Fixed Platforms • Steel template Structures

• Concrete Gravity Structures

Upto 500ft (150m)

2. Compliant tower • Compliant Tower

• Guyed Tower

• Articulated Tower

Upto 500ft (150m)

3. Floating Structures Semi-submersible Platform 600 to 6,000 ft (180 to 1,800 m).

Tension-leg platform 6,000 ft (2,000 m)

FPSO

Operational for large depths upto 10000ft (3000m)

Various offshore Structures and their general operational depth.

Looking at the various options available, we found TLP, Semi submersible and FPSO as the

choices as according to operational water depths(850m). But TLP and Semi submersible need

separate storage unit which an FPSO doesn’t need. Moreover, the installation of FPSO is much

easier and cost effective as compare to TLP and Semi Submersible. That’s why we selected the

FPSO as the wisest choice for this production field.

Advantages of FPSO at time of decommissioning:

• Due to the barge shape of FPSO, it is relatively easier to transport it to conversion yards and then to the new field. This minimizes the offshore work and hence, is economical.

• Crane vessels are not required for offshore module separation unlike fixed platforms where structural connections are cut; modules are removed, placed on barges and transported to yard.

• Extensive underwater cutting is not required in FPSO as compared to fixed structures, and hence, no more complicacies that are associated with the cutting mechanism. No adverse


effects on environment that generally results due to the disposal of drill cuttings on the seabed. The cost of offshore work also drastically reduces due to all these factors.

• No partial removal of the structure as in case of gravity based structures or fixed jacket structures. Structure, which is either toppled or partially left on seabed, may affect adversely the sea environment like fishing and navigation. But that does not happen in case of FPSO.

The Team Organization

The design team consists of five third year, UG , students of the Department of Ocean

Engineering and Naval Architecture, Indian Institute of Technology, Kharagpur working under

guidance of Prof. S.C. Misra. The competency areas are:-

Fundamental Competencies:

• General Arrangement and Overall Hull or System Design

• Weight, Buoyancy and Stability

• Strength and Structural Design - General

• Construction, Fabrication, and Installation

• Risk Assessment

Specialized Competencies - Floating Structures

• Wind and Current Loading • Mooring/Station Keeping Power Generation, Distribution, and Electric Load Analysis

The team members and competency areas headed by them are:

Name( alphabetic order) Competency Area

1 ASHISH KUMAR JHA • General Arrangement and Overall Hull or System Design

• Power Generation, Distribution, and Electric Load Analysis

2 GYANENDU SAHOO • Weight, Buoyancy and Stability

3 PRABHAKAR TIWARI • Wind and Current Loading • Mooring /Station Keeping

4 SAURABH SINGH • Construction, Fabrication, and Installation • Risk Assessment

5 VIVEK GUPTA • Strength and Structural Design

Each member of team headed a set of competency area. The competency areas ‘Weight,

Buoyancy and Stability’ and ‘Strength and Structural Design’ being very time consuming were


assigned to one person each. The entire process of designing the FPSO is iterative in nature

where the output from one competency area is input to another and vice versa. The design steps

are repeated and corrected until satisfactory results are produced. The entire process can be

suitably represented by the flow chart shown below.

Planning and Scheduling of Tasks

The iterative design process made it necessary to plan the entire process. The team worked on a

number a number of competency areas simultaneously to minimize the duration of project and

complete the work in time. Suitable decisions were taken in case of conflicting requirements or


results among various competency areas. The scheduling of the project is shown by help of Gantt

chart shown below.


The production process

The diagrammatic representation of entire production process:

The oil freshly coming out of well contains gaseous hydrocarbons and water which are extracted

at H.P./L.P. separators. After this processing, the oil that is produced is in emulsion form. This

oil is allowed to settle for about a day and later chemical and electrical treatments are done to

ensure acceptable levels of moisture in oil. For this we need two tank sets (tank set 5 and tank

set6, i.e. Cargo5.1, Cargo5.2, Cargo5.3, Cargo6.1, Cargo6.2, Cargo6.3). On a particular day one

tank is being filled while from other emulsified oil is withdrawn and dehydrated and stored in

another cargo tank. Produced water is stored in Slop tanks and they are considered to be 50% full

in all the cases to consider worst case. Also MDO tanks in engine room and fresh water tanks

were considered 50% full for maximum surface effect. The offloading is also complicated by

fact that while dehydrated oil is being offloaded, emulsified oil is being stored in one of the

tanks(5 or 6) and emulsified oil from previous day is being continuously dehydrated and stored

in another tank.

The rate of transfer of crude and oil emulsion:

(a)Rate of production of emulsion from H.P./L.P. separators = 13250m3/hr (2million barrels

production capacity)

(a)Rate of transfer of emulsion from one tank to another (dehydration) =1325m3/hr

(b) Rate of transfer of crude from FPSO to shuttle tanker = 6625m3/hr

Oil/GasSeparator

ProductionfromWellhead

DEHYDRATORWETGAS

WETOIL

RECOVEREDOIL

OILDEHYDRATION

DRYOIL

STORAGE

GRAVITYSEPERATION

GRAVITYSEPERATION

GAS-FLOATATIONSEPARATION

TRANSPORTTOSHORE

PRODUCTIONWATERDISCHARGE

DISPLACEMENTWATERDISCHARGE

DRYGAS

ONBOARDCONSUMPTION

COMPRESSIONANDREINJECTION


The topside of the FPSO has following processing capacity:

• Oil storage: 2,000,000b/d

• Oil Production: 200,000b/d

• Liquids treatment: 300,000b/d

• Produced water treatment: 180,000b/d

• Water Injection: 390,000b/d at 150 bar

• Seawater Sulfate Removal : 400,000b/d

• Gas injection: 8,000,000Sm3/d at 285 bar

For proper designing of FPSO the production and offloading schedule has to be decided. The

following 12 day cyclic production schedule was decided. This was necessary to know the state

of FPSO during offloading, as the stability of FPSO has to be considered in worst case i.e. when

surface effect is maximum. The FPSO is assumed to be working in normal conditions and there

is no delay in schedule of shuttle tankers. The shuttle tanker arrives on 6th day and on departs on

7th day. Next the shuttle tanker arrives on 8th day and departs on 12th day.(The days represent

only the time at which the shuttle tanker is ready to offload and the time spent on positioning and

mooring the FPSO is assumed to be before and after the respective days.) The stability during

offloading has been considered under ‘Weight, Buoyancy and Stability’ competency area as

“Day6” and “Day11” type heading.

Color Code

oil empty emulsion

Day/Tank 1 2 3 4 5 6 7 8 9 10

Day1 empty empty empty empty full empty empty empty empty empty

Day2 empty empty full empty empty full empty empty empty empty

Day3 empty empty full empty full empty empty full empty empty

Day4 full empty full empty empty full empty full empty empty

Day5 full empty full empty full empty empty full empty full

Day6 full full full empty empty full empty full empty full

Day7 empty empty empty empty full empty empty empty full empty

Day8 empty empty full empty empty full empty empty full empty

Day9 empty empty full empty full empty empty full full full

Day10 full empty full empty empty full empty full full full

Day11 full empty full empty full empty empty full full full

Day12 empty empty full empty empty full empty empty empty empty


COMPETENCY AREAS

1. GENERAL ARRANGEMENT & HULL DESIGN REPORT

The aim of the general arrangement task is assignment of spaces for all the required functions

and equipments, properly coordinated for location and access. Before this it is necessary to

estimate the dimensions of the FPSO.

Fig. 1.1: Profile and Plan View

1.1 Preliminary Analysis: Determination of Dimension

For the preliminary analysis a data set of existing FPSOs was created by extensive search through various journals on Naval Architecture and Ocean Engineering.The data is shown in Table 1.1 of Appendix 1. The data was used in initial estimation of length (L), breadth(B), Depth(D), draft(T) of the FPSO. The results from the preliminary analysis were checked against regulations of ‘International Convention On Load Lines, 1966’. The height of double bottom were checked against the rules of MARPOL Annex 1.

First step in determination of dimensions is to estimate the L/B, B/D and T/D ratio of FPSO. A

graph of ratios vs storage capacity was plotted and corresponding equations for the ratio was

found by linear curve fit. The graph and results are shown below.


0.0 5.0x104

1.0x105

1.5x105

2.0x105

2.5x105

3.0x105

3.5x105

4.0x105

1

2

3

4

5

6

7

Data Plot FPSOR

atio

(L/B

, B

/D, T

/D)-

-->

Storage Capacity(m3)--->

L/B B/D T/D

Fig 1.2 Preliminary Estimate of Dimensions

Equations from linear curve fit:-

L/B=5.76265-1.14349*10^-6*Storage

B/D=1.9456-2.19749*10^-7*Storage

T/D=.6653+1.41368*10^-7*Storage

Desired Storage=2million barrels=317974.6m3

L/B=5.4 B/D=1.9 T/D=0.71

In order to estimate the dimensions of the FPSO volume of the FPSO below the main deck and

between the perpendiculars were obtained by two formulae and matched iteratively. For a given


length of FPSO all other dimensions were calculated using the ratios calculated above. Then two

volumes and percent error between them was calculated. The error between the volumes must be

less than 0.25%. The required dimensions were the ones for which the above error condition was

satisfied.

Vh = CBD*L*B*D; C BD =C B+(1-C B)[(0.8D-T)/3T]

&

Vh = Volume required for cargo + Volume required for Ballast + 15%of LBD (for engine room

slop etc.)

The double bottom height and width of side tanks were assumed to be 2.5m and calculations

were done then they were checked against MARPOL rules. (This was a guess work, if the

assumed values didn’t satisfy the regulations new values were assumed and calculations were

done again).

Code for the preliminary estimate of dimensions:

L=305.2; %input length(m) of fpso Cb=0.98; %block coefficient B=L/5.4; %Breadth(m) of fpso D=B/1.9; %depth(m) of fpso T=D*0.71; %draft(m) of fpso V1=2*(10^6)*0.158987/.95/.98+2.5*L*B+2*2.5*L*(D-2.5)+0.15*L*B*D;%Req.Capacity Volume m3 Cbd=Cb+(1-Cb)*(0.8*D-T)/(3*T);%Assuming no sheer and camber V2=L*B*D*Cbd; %Estimated capacity volume(m3) disp((V2-V1)/V1*100);%error:This should be less than 0.25%

Results L=305.2m B=56.52m D=29.8m T=21.12m Cb=0.98

The results we get here are just a preliminary analysis and does not carry enough importance. However design process being iterative process, it gave us a raw data for the iterations. Later on


when weight calculations were done and matched with buoyancy, slight change in design draft (T=22m) had to be done ,the remaining dimensions remaining unaltered. Final Results L=305.2m B=56.52m D=29.8m T=22m

Cb=0.98 Freeboard=7.8m

1.2 Check the freeboard rules with ILLC (only important applicable rules to FPSO

mentioned)

Regulation27: Defines freeboard computation for ship shaped structures as ’Type A’ and Type

‘B’. Our FPSO satisfied the requirements of ‘Type A’.

Regulation28: Gives a table for computation of tabular freeboard. Tabular freeboard

obtained=3.256m

Regulation30: Where the block coefficient (Cb) exceeds 0.68, the tabular freeboard specified in Regulation28 shall be multiplied by the factor ((Cb+0.68) / 1.36). Correction to Cb= 3.256*(Cb+0.68)/1.36 = 3.974m Regulation31: Where D exceeds (L / 15) the freeboard shall be increased by (D-(L / 15))R mm,

where R is (L / 0.48) at lengths less than 120 metres and 250 at 120 metres length

and above.

Correction due to depth=2.3m Freeboard=3.974+2.3 =6.274m

Regulation38: Not considered as no Sheer or Camber in FPSO

Regulation33: No deduction due to Superstructures taken into account.

Regulation 39: The bow height defined as the vertical distance at the forward perpendicular between the waterline corresponding to the assigned summer freeboard and the designed trim and the top of the exposed deck at side shall be not less than:

7000(1.36 / (Cb+0.68))mm ( for ships of 250 metres and above in length)

Min. Bow Height= 7000(1.36/(Cb+0.68))=5.73m < 8.4 Regulation 40: The minimum freeboard in summer shall be the freeboard derived from the tables In Regulation 28 as modified by the corrections in Regulations 27, as applicable, 29, 30, 31, 32, 37, 38 and, if applicable, 39. Min Freeboard=6.274m which is less than the freeboard of FPSO i.e.7.8m. So, ILLC rules are

satisfied by the FPSO.


1.3 Check wing tanks and double bottom thickness from Annex I of MARPOL 73/78

Regulations:

a)The minimum width of the side tanks as specified in the rules is w = 0.5 + (DW/20000) (m) or w = 2.0 m, whichever is the lesser. Deadweight (DW) is an expression of a ship's carrying capacity, including the weight of the crew, passengers, cargo, fuel, ballast, drinking water, and stores. At this stage the deadweight is not determined. But the cargo weight is known (2million barrels; density of crude=0.9tonnes/m3; 1 barrel=0.159m3)= 286200 tonnes. The dead weight is going to be larger than this value. We calculated ‘w’ by using cargo weight as dead weight. Then w=14.81m. According to the rule then w=2m, the minimum width of side tanks. We took the side tank width at 2.5m, so this regulation is satisfied. Even when the deadweight of the ship was accurately known at later stage this result need not be rechecked as the application of above result will lead to w>14.81m(when calculated using accurate deadweight) as a result the minimum ‘w’ from regulations remains same at 2m. b) The minimum height of double bottom according to regulations is: h = B/15 (m) or h = 2.0 m, whichever is the lesser. The minimum value of h = 1.0 m. For the FPSO h= 56.52/15=3.786m. So the minimum value of ‘h’ is 2m. We took double bottom height to be 2.5m. So this regulation is also satisfied. 1.4 Determination of frame spacing: Rules for frame spacing:

a) The normal frame spacing between aft peak and 0.2L from F.P. may be taken as: 450+2L [mm] for transverse framing and 550 + 2L [mm] for longitudinal framing. However, it is generally not to exceed 1000mm

b) Elsewhere, the frame spacing is not to exceed the following: In peaks and sterns: 600[mm] or as in (a) whichever is lesser. Between collision bulkhead and 0.2L from perpendiculars

Using the above rules the transverse framing were fixed in the following manner: Frame 0-16 --- 600mm Frame 16-86 --- 750mm Frame 86-287 --- 900mm Frame287-288 --- 850mm Frame 288-357 --- 750mm Frame 357-373 --- 600mm The frame spacing is in the domain of ‘Strength and Structural Design’ Competency area. The information for frame spacing was needed in ‘General Arrangement’ to fix tank and compartments as the bulkheads separating all the tanks and compartments must line on frames. The web frames were also decided to be placed at every fifth frame. 1.5 Determination of Slop Tank and Fuel Oil tank Volumes: The total capacity of cargo tanks is known at this point. We need to estimate the volume of slop tanks and Diesel tanks for the FPSO. In absence of any reliable data, the estimation was carried out by plotting the data collected and finding the required volume by curve fitting.


0.0 2.0x104

4.0x104

6.0x104

8.0x104

1.0x105

1.2x105

1.4x105

1.6x105

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

6500

7000

7500

8000

Slop Tank Volume =170.28334+.04392*xFuel Oil Volume= 215.05236+.02412*x

Tan

k V

olu

me(m

3)-

-->

Storage(m3)--->

FUEL OIL TANK SLOP TANK

Fig1.3 Estimation of Fuel and Slop Tank volumes

Slop Tank Volume for 2 milliom barrel(317974m3) = 170.28334+.04392*317974=13965.462 m3

Fuel Tank Volume for 2 milliom barrel(317974 m3) = 215.05236+.02412*317974=7884.59 m3

These values rounded off and finalvolumes were decided to be:-- Slop Tank Volume=14000 m3

Fuel Tank Volume=8000 m3

1.6 Position of Tanks and Compartments considering transverse frames: The naming of cargo tanks is shown below. ‘x’ represents the set of tanks being considered. x=1 for set of tanks placed just after the engine room compartment and continues till x=10, after which we have slop tanks.


Fig 1.4: Cargo and Ballast Tanks

Fig 1.5 : Frames where bulkheads are located

Check MARPOL Regulation: ’MARPOL Regulation 24,’ was used to determine the size and position of tanks. Since it involves the use of hypothetical rate of oil outflow in case of damage, the determination of size of tanks and position are reported under ‘Weight, Buoyancy and Stability’ competency area . The tanks sizes reported above satisfy the Regulation 24 of MARPOL. The frame number, length, breadth, height and position of tanks are shown in Table1.2 of Appendix 1.

<---Ballast bottom x.1

<---Ballast bottom x.2

<---Ballast bottom x.3Cargo x.1

Cargo x.2

Cargo x.3

Ballast Starboard x

Ballast Port x

Fr.0 Fr.16 Fr.56,58 Fr.90 Fr.117 Fr.144 Fr.171 Fr.198 Fr.225 Fr.252 Fr.279 Fr.310 Fr.342 Fr.357

Fr.373

EN

GIN

ER

OO

M


1.7 Engine Room Layout The selection of engine-generator sets are discussed under ‘Power Generation, Distribution and Electrical Load Analysis’ competency area. ENGINE ROOM LAYOUT

(a)ELEVATION

Fig 1.6: Engine Room layout : Elevation


(b) PLAN -Level 0

Fig 1.7 Engine Room layout : Plan: Level 0


(b)PLAN: Level 1

Fig 1.8: Engine Room layout : Plan: Level 1


(c)PLAN: Level 2

Fig 1.9: Engine Room layout : Plan: Level 2

Emergency Generator6L26


1.8 Accommodation Layout In offshore industry workers have to work under harsh conditions for extended periods of time. The quality of the accommodations where offshore installation crews sleep, eat and relax influences their job performance and overall sense of comfort and well-being. In order to provide comfortable and relaxing atmosphere to the crew of FPSO, the guidelines of ‘Crew Hability on Offshore Installations, ABS’, were followed and all effort were made to provide facilities in excess of those mentioned in the rules. The FPSO needs 120 workers during normal operations and may need up to 150 people during repairs and installation. The accommodation has been designed to support 120 people. Separate room for every worker has been provided. However during repairs and installation some workers may have to share the rooms. In total FPSO has 120 rooms, 20 on each of the 6 floors. Separate sanitary spaces have been provided for each worker although the rules require sanitary space for every 6 workers. Seventh floor is for officers and their offices. On top of accommodation is helideck which is large enough for a S-61 helicopter capable of carrying up to 30 people and payload (fuel and cargo) of up to 3200kg.

UITILTY/FACILITY MINIMUM REQUIREMENT FROM RULES

PROVIDED

• Berthing floor area per crew member includes berths, lockers, chest of drawers and seats

Minimum berthing floor area for 1 person room = 4.75 m2/person

Berthing floor area for 1 person room = 17.19 m2/person, officers provided with drawing room

• Sanitary spaces

Free space area per person in sanitary spaces = 0.75 m2 or 1.1 m2

Each room provided with separate toilet, area=3.78 m2

Headroom in all sanitary spaces = 1980 mm (78 in ) or 2050 mm (80 in).

Headroom provided=2.15m

Width of toilet stall is 810 mm (32 in).

Width of toilet stall is 1.74m

• Food service areas

Headroom in all food services area = 1980 mm (78 in ) or 2050 mm (80 in).


Door width to mess room = 915 mm (36 in).

Door width to mess room = 1.92m.

Door width to galley, pantry, kitchen and storeroom = 760 mm (30 in)

Door width to galley, pantry, kitchen and storeroom = 1.94m.

Width of door to freezer and Door width to freezer and


cold storage rooms = 900 mm (35 in ) and open 180 deg

cold storage room = 1.94m.

Deck area requirements for planned seating capacity are: - at least 1 m2 (10.8 ft2) or 1.7 m2 (18.4 ft2) per person for officers and ratings=238(taking 1.7/ m2person)

Total seating area available = 300 m2 (two floor each 159 m2 i.e. total area =300 m2)

• Recreational areas

Headroom = 1980 mm (78 in ) or 2050 mm (80 in).


The recreational area(s)’ goal is to provide space for 1/3 of the crew to participate simultaneously in some form of leisure activity

For every floor recreational area is provided.

The deck area provided for crew member exercise for each physical fitness station within the space:

- is at least 1.85 m2 (20 ft2) - is at least 4.5 m2 (48 ft2).

Provided.

A central stowage area for books is provided with at least 300 mm (12 in) of shelving for every five crew members.

Provided.

At least one seat and writing surface is provided in a recreation lounge for every six crew members.

Provided.

Medical

Headroom = 1980 mm (78 in ) or 2050 mm (80 in).


The medical accommodations are fitted with berths in the ratio of 1 berth to every 12 crew members or portion thereof, which are not berthed in single occupancy rooms.

Provided.

Table 1.1: ABS requirements for Accommodation


Escape Route in Accommodation The first priority for designing an accommodation for an FPSO is safety. In the accommodation layout below the escape route to lifeboats have been clearly shown with red arrows. The rules make it mandatory for access to life boats both from inside and outside the accommodation. Therefore the stairs case in accommodation is designed to act like a staircase well during emergency, so that workers can easily reach floor4 where lifeboats are kept. Also, stairs have been provided outside of accommodation (shown in red). An escape plan on the main deck is also necessary. This is shown in general arrangement of topsides. Plan of Room

Fig 1.10: Plan of Living Quarters

Plan of Helideck

Fig 1.11: Plan of Helideck

Officer Room

RO

OM

Worker Room

BE

D R

OO

M


Isometric view of Accommodation

Fig 1.12: Isometric view of Accommodation


Plan of Floor 1

Fig 1.13: Plan of Floor 1

ROOMROOMROOMROOMROOMROOMROOM

ROOM

ROOM

ROOM

ROOM

ROOM

ROOM


SHAFTFORKITCHEN


Plan of Floor 2 and 5

Fig 1.14: Plan of Floor 2 and 5


ROOM

ROOM

ROOM

ROOM

ROOM

ROOM


SHAFTFORKITCHEN

KITCHEN

MESSANDSERVINGCOUNTERS


Plan of Floor 3 and 6

Fig 1.15: Plan of Floor 3 and 6


ROOM

ROOM

ROOM

ROOM

ROOM

ROOM


MEDICALAREA

EXERCISE AREA

STORAGE ANDLAUNDRY(crew laundry,clean linen, crewbaggage andlockers )

SHAFTFORKITCHEN


Plan of Floor 4

Fig 1.16: Plan of Floor 4

SHAFTFORKITCHEN


ROOM

ROOM

ROOM

ROOM

ROOM

ROOM


SHAFTFORKITCHEN


Plan Floor 7(for Officers)

Fig 1.17: Plan Floor 7(for Officers)

SHAFTFORKITCHEN

BE

D R

OO

M

BE

D R

OO

M

BE

D R

OO

M

BE

D R

OO

M

BE

D R

OO

M

BED ROOM

Officers Residencial Area

Officers working Area


1.9 Topsides The general layout of the topsides is governed by safety considerations with the most hazardous equipment being arranged away from the accommodation area. Therefore modules like Turret, LP/HP Separator, Inlet Manifold. Gas Dehydration Module, Lift Gas Compressor Module have been placed as far from accommodation as possible and Water Injection Sulphate removal Module, Lay down Areas and Local equipment Room are placed aft of these modules. The flare being most dangerous component has been placed in bow region. Other considerations include ‘Green Water’ which is wetting of main deck by waves. This must be avoided in FPSO. So a gap of 2.5m has been given between the main deck and topside modules. Providing this gap also allows workers to move from one part of FPSO to another without much hindrance as all the topside components are arranged above. Same gap has been given for pipe rack also. Also a covered emergency access route has been put in this gap so that workers can be evacuated quickly, without any loss of life, in case of an emergency. Such a design, where topside modules and pipe racks are placed above the main deck, creates its own problems with respect to designing the FPSO. The general position of modules was decided by safety concerns, but exact position had to be decided by taking framing of FPSO into account. As stated earlier web frames are placed every fifth frame. The modules and pipe racks were placed onto every fifth frame. The construction details have been shown in ‘Construction, Fabrication and Installation’ competency area. The frame number shown below in the tables are the frame numbers on which the FPSO is placed. For example, for Pipe rack - main 1(MPR1) the frame no. are 170-185. This means MPR1 has been placed on web frames between frame number 170-185 (i.e. 170, 175,180 web frames support this pipe rack). This however does not mean that module or pipe racks do not extend beyond these frames. These frames only support the topsides. The exact extent of modules and pipe racks are shown by ‘Position’ column of the table below.

TOPSIDE MODULE Module

No. POSITION

Frame X(m , m) y(m , m) z(m , m)

From To From To From To

Pipe rack - main 1 MPR1 170-185 133.07 153.771 -3.11 +3.15 32.30 52.44




Pipe rack - truncated 1 TPR1 65-105 56.31 69.133 -3.15 +3.15 32.30 40.31

Pipe rack - truncated 2/1 TPR2/1 95-110 69.70 85.10 -3.17 +3.13 32.30 40.67







Pipe rack - truncated 5 TPR5 295-315 249.63 265.063 -2.43 +3.53 32.30 41.70

Flare Tower M1 N.A. 275.72 286.114 -3.50 +16.71 29.80 95

Lay down area M6 160-175 127.48 142.075 -3.50 -27.35 32.30 42.3

Lay down area M10 135-165 112.88 142.075 -3.50 -27.35 32.30 42.3

Lift gas compressor M12 190-210 150.37 179.347 -3.50 -26.53 32.30 45.85

Gas dehydration M13 245-275 209.56 227.347 -3.50 -22.36 32.30 49.64

Chemical injection package & utilities

M23 225-240

181.08 208.056 -3.50 -26.52 32.30 47.70

Inlet Manifold M31 220-250 182.56 212.856 +3.30 +26.90 32.30 57.27

LP / HP Separation M33 195-210 151.59 179.634 + 3.50 +24.88 32.30 47.37

Water Injection- sulphate Removal & Water treatment

M42 140-170

108.07 141.719 + 3.50 +27.10 32.30 49.90

Local Equipment Room M51 100-140 80.73 110.303 -3.50 -26.40 32.30 50.55

Turret TR N.A.

Rest Room 1 RR1 90-101 65.7 75.6 +8.76 +25.76 29.8 32.8

Rest Room 2 RR2 90-101 65.7 75.6 -8.76 -25.76 29.8 32.8

Rest Room 3 RR3 297-310 250.60 260.35 +8.76 +25.76 29.8 32.8

Rest Room 4 RR4 297-310 250.60 260.35 -8.76 -25.76 29.8 32.8

Table 1.2: Topside Definitions

ESCAPE ROUTE ON TOPSIDE The escape route was decided under ‘Risk Assessment’ competency area. The details of escape route are discussed in Section 7.9 of Risk Assessment. The escape route is shown below with red arrows and evacuation zones and life boats are clearly marked. The yellow line in the Figure 1.18 separates the evacuation zones 2 and 3.


Fig 1.18: Topsides : Plan View

Ev

acu

atio

n Z

on

e 1

Ev

acu

atio

n Z

on

e 2

Ev

acu

atio

n Z

on

e 3


2. WEIGHT, BUOYANCY AND STABLITY REPORT

2.1 Weight and Buoyancy

Preliminary Estimates: In the general arrangement report only preliminary estimates of

dimensions of FPSO have been shown. The accurate knowledge of total weight and buoyancy is

necessary for determination of full load draft and scantling draft. These drafts are used in

estimation of maximum bending moment for which the FPSO has to be designed. The details are

presented in ‘Strength and Structural Design’ competency area. The preliminary weight

estimation was determined by ‘Ship Design for Efficiency and Economy H. Schneekluth and V.

Bertram’.

To begin with an idea of weight of various components of FPSO had to be made. The

components are Machinery Weight, Accommodation Weight, Hull Weight, Weight of

Production Modules and Pipe Racks. Later on as the work progressed, more accurate estimates

of the weights were used.The outfit weight was included in weight of modules.

(a)Power Plant Weight: Exact Power Plant weight could be known only when the engine and generators were selected in ‘Power Generation, distribution and Electric Load Analysis’ competency area. Until this was done we had to rely on preliminary estimation of weight. The estimated power of FPSO was about 85MW which has been taken from similar FPSOs.

Wm= 0.72*MCR0.7= 2277tonnes

Once the engine was selected, the manufacturer data were available and exact weight of the power plant was known:

Item No.

Pieces DESCRIPTION Weight (including liquids)Kg/unit

Total Weight (tonnes)

1 5 Engine Generator Set 350,000 1750 2 5 Auxiliary module including 9150 45.75 3 5 Trunk Route Pipe Rack 2500 12.5 4 2 Booster Unit 2500 5 5 5 Lube Oil Separator Unit 1520 7.6 6 2 Maintenance Water Tank 11500 23 7 5 Cooling Water Expansion Vessel 1500 7.5 8 12 Oil Wetted Filter 2114 25.37 9 5 Charge Air Silencer 820 4.1

10 1 Steam Header 770 0.77 11 12 Ventilation Unit (Engine Room) 2700 32.4 12 6 Ventilation Unit (Auxiliary Area) 2100 12.6 13 2 Working Air Unit 545 1.09 14 1 Starting Air Unit 1700 1.7 15 4 Starting Air Bottle 1500 6


16 5 Exhaust Gas Silencer 7200 36 17 1 Heat Recovery System Container 35000 35 18 1 Black Starting Unit 5500 5.5 19 30 Cooling Water(LT/HT)-Radiator 3750 112.5 20 3 Exhaust Gas Boiler 34000 102 21 1 Fire/Raw water Tank 316000 316

Total Weight 2542.38 t Table 2.1: Final Weight Chart of Power Plant

The final weight of engine generators and its components were 2542.38tonnes. (b)Accommodation Weight: The preliminary estimate of Accommodation was 2000 tonnes, taken

from similar FPSOs. Once the accommodation layout was done in general arrangement, the

weight per unit floor area of accommodation was taken as approximately 250kg/m2.The weight

of accommodation thus finalized was

Wacco=250*51.52*20*7*/1000=1803tonnes

To this the weight of helipad was added, which was 70tonnes (taken from www.aluminium-

offshore.com).

So final weight of accommodation was W=1873tonnes.

(c) Weight of the Topside Modules:

The weight of topside modules and their CGs are shown in table below:

TOPSIDE MODULE Module No. Operating

Weight (tonnes)

Lift weight (tonnes)

Pipe rack - main 1 03/MPR1 Pipe rack - main 2 03/MPR2 Pipe rack - main 3 03/MPR3 Pipe rack - main 4 03/MPR4 Pipe rack - truncated 1 03/TPR1 Pipe rack - truncated 2/1 03/TPR2/1 Pipe rack - truncated 2/2 03/TPR2/2 Pipe rack - truncated 3/1 03/TPR3/1 Pipe rack - truncated 3/2 03/TPR3/2 Pipe rack - truncated 4/1 03/TPR4/1 Pipe rack - truncated 4/2 03/TPR4/2 Pipe rack - truncated 5 03/TPR5 Flare Tower 1 Lay down area 6


Lay down area 10 Lift gas compressor 12 Gas dehydration 13 Chemical injection package & utilities

23 LP / HP Separation 31 Inlet Manifold 33 Water Injection,sulphate Removal & Water treatment 42 Local Equipment Room 51

Turret TR Table 2.2: Weight and CG of topside modules

(d)Hull Weight: Preliminary estimate of hull weight was necessary because the total weight(of

which hull weight is a significant component) determines the draft of the FPSO, then these draft

values are used to estimate the maximum bending moment and then the corresponding mid-ship

section is determined. The scantlings and plates cross-section area is used to determine weight

per unit ship length and then the hull weight of the FPSO. The estimated and calculated weights

of FPSO must match in acceptable limits , therefore an iterative process was followed. The first

estimate was made using the formula given in DNV 1972, rules for tankers. This was done to get

an initial value and reduce the number of iterations.

First estimate of hull weight:

Using this estimate the weight of hull was calculated as described in ‘Strength and Structural

Design’ competency area. After a number of iterations the hull weight was 26000.7 tonnes.

(e)Weight of Tanks when completely full: The tanks were modeled in ‘Hydromax’ and it was

necessary to calculate the storing capacities of various tanks to check if the FPSO met the

required storing and processing capacity.The tanks were assumed to have a permeability of 0.95


and it was also assumed that they were only 98% filled when full and 2% filled when empty.

This is because of the restrictions on the pumping capacity of the pumps.

• Cargo Tanks: The FPSO must Store 2 million barrels of oil.

Tank Permeability % full Weight (tonnes)

Cargo 1.1 0.95 98% 9442

Cargo 1.2 0.95 98% 9731

Cargo 1.3 0.95 98% 9442

Cargo 2.1 0.95 98% 9327

Cargo 2.2 0.95 98% 9612

Cargo 2.3 0.95 98% 9327

Cargo 3.1 0.95 98% 9327

Cargo 3.2 0.95 98% 9612

Cargo 3.3 0.95 98% 9327

Cargo 4.1 0.95 98% 9327

Cargo 4.2 0.95 98% 9612

Cargo 4.3 0.95 98% 9327

Cargo5.1 0.95 98% 9327

Cargo 5.2 0.95 98% 9612

Cargo 5.3 0.95 98% 9327

Cargo6.1 0.95 98% 9327

Cargo 6.2 0.95 98% 9612

Cargo 6.3 0.95 98% 9327

Cargo7.1 0.95 98% 9327

Cargo 7.2 0.95 98% 9612

Cargo 7.3 0.95 98% 9327

Cargo8.1 0.95 98% 9327

Cargo8.2 0.95 98% 9612

Cargo 8.3 0.95 98% 9327

Cargo9.1 0.95 98% 9423

Cargo 9.2 0.95 98% 9711

Cargo 9.3 0.95 98% 9423

Cargo10.1 0.95 98% 9212

Cargo 10.2 0.95 98% 9493

Cargo 10.3 0.95 98% 9212

Total

Weight 282951

Table 2.3: Weight of cargo tanks

The total storing capacity of FPSO is approximately 282951 tonnes.

Taking one barrel=0.159m3, and density of crude oil 0.8883tonnes/m3


282951 tonnes = 2,003,339.005barrels of oil= 2.003339 million barrels of oil.

Thus the FPSO meets the requirement of storing 2million barrels of oil.

• Slop Tanks: The FPSO must have capacity to store 14000m3 of slops (determined in

general arrangement).


Slop tank1 0.95 98% 4438

Slop tank2 0.95 98% 4574

Slop tank3 0.95 98% 4438

13450

Table 2.4: Weight of slop tanks

The FPSO has a Storing Capacity of 13450 tonnes = 14731.65m3 > 14000m3

• Fresh Water Tanks: These tanks are necessary for storing potable water for the crew.

According to regulations the capacity must be at least 0.2t/(person x day). The supplies

reach FPSO every 30 days and during repairs as many as 150 people may be onboard the

FPSO. So, minimum capacity of the tanks are 900tonnes.


FW Tank Port 0.95 98% 509.4 FW Tank Starboard 0.95 98% 509.4

Total

Weight 1018.8 Table 2.5: Weight of fresh water tanks

The storing Capacity of FW tanks is greater than the minimum required by the rules.

• MDO Tanks: These tanks stored MDO (marine diesel oil) for the engines to work in case

of shortage of gas produced from oil field. The minimum capacity for these tanks are

8000 m3=6720tonnes( density of MDO=0.84 tonnes/m3)


MDO Tank Port 0.95 98% 3519.18 MDO Tank Starboard 0.95 98% 3519.18

Total

Weight 7038.18 Table 2.6: Weight of MDO tanks


Enough storing capacity is available for MDO.

(f) Calculation of Full Load Draft and Ballast Draft

The FPSO was modeled in Hydromax and the calculations were done. The modeling and

detailed results(along with the definitions for various load cases) are shown in Appendix2.4. The

Full Load Case, Ballast Load Case are used in mooring calculations and for structural

calculations Full Load Case, Ballast Only Case, Cargo Only Case was used.

CASE Displacement of FPSO( tonnes) Draft(m)

Full Load Case 386360 22

Ballast Load Case 140543 7.985

Ballast Only Case 165780 9.44

Cargo Only Case 345696 19.705

Table 2.7 Calculation of various drafts of FPSO

2.2 STABILITY: The US Navy Criteria to check both intact static and intact dynamic

stability.

Winds cause heeling moments that tend to capsize a floating structure. The FPSO must be

designed to remain stable and seaworthy under the conditions specified by the criteria chosen to

test the stability. In our case we have chosen US Navy criteria. The intact stability is checked

under a wind whose speed depends on the service conditions. All vessels that must withstand

tropical storms should be checked for winds of 100 knots. The values of GZ for this criteria is

effective GZeff, which is calculated taking into account the free surface effect. The formula for

wind arm is:

where V is the wind velocity in knots, A, the sail area in m2, l, the distance between half draught

and centroid of sail area in m and , the displacement in tones.

The first angle of static equilibrium is st1. The criteria for static stability requires that the

righting arm at this angle be not larger than 0.6 of the maximum righting arm. To check the

dynamical stability the regulations assume that the ship is subjected to a gust of wind while

heeled 25 to the windward of st. The area ‘a’ between the wind heeling arm and the righting arm


curves up to st1, and the area ‘b’ between the two curves, from the first static angle , up to the

second static angle, st2 , or up to the angle of downflooding whichever is less. The ratio of area

‘b’ to area ‘a’ should be at least 1.4.

Fig 2.1: The US Navy criteria

2.2.1 INTACT STABILITY

The intact stability of FPSO was considered for as many cases as possible. The stability of FPSO

not only depends upon it’s dimensions but also factors like blowing wind and free surface effect.

So before we can judge stability of FPSO we have to consider various scenarios under which an

FPSO may operate, and check it’s stability in all those scenarios. Since during offloading the free

surface effect will be maximum ,therefore we analysed the stability of FPSO while offloading.

An important assumption is that free surface effect from the topside modules have been

neglected due to non availability of data.

The oil freshly coming out of well contains gaseous hydrocarbons and water which are extracted

at H.P./L.P. Separators. After this processing, the oil that is produced is in emulsion form. This

oil is allowed to settle for about a day and later chemical and electrical treatments are done to

ensure acceptable levels of moisture in oil. For this we need two tank sets (tank set 5 and tank

set6, i.e. Cargo5.1, Cargo5.2, Cargo5.3, Cargo6.1, Cargo6.2, Cargo6.3). On a particular day one

tank is being filled while from other emulsified oil is withdrawn and dehydrated and stored in

another cargo tank. Produced water is stored in Slop tanks and they are considered to be 50% full

in all the cases to consider worst case. Also MDO tanks in engine room and fresh water tanks


were considered 50% full for maximum surface effect. The offloading is also complicated by

fact that while dehydrated oil is being offloaded, emulsified oil is being stored in one of the

tanks(5 or 6) and emulsified oil from previous day is being continuously dehydrated and stored

in another tank.

The rate of transfer of crude and oil emulsion:

(a)Rate of production of emulsion from H.P./L.P. separators = 13250m3/hr (2million barrels

production capacity)

(a)Rate of transfer of emulsion from one tank to another (dehydration) =1325m3/hr (b)Rate of transfer of crude from FPSO to shuttle tanker = 6625m3/hr

The percentage of tank filled mentioned below, implies that tank set x is filled to that level. The

tank set includes Cargox.1, Cargox.2 and Cargox.3. So, a tank set will be filled with wing tanks

Cargox.1 and Cargox.3 being filled simultaneously and then the central tank Cargo x.2. This

process may take place vice-versa. However in order to maximize the surface effect and take into

consideration worst case scenario we assume that all the three tanks are being filled

simultaneously.

Stability during offloading: Three cases were considered in offloading of FPSO, one in which all

the tanks of FPSO are full and it is emptied completely, second and third cases the ones

described as Day6 and Day11 type of unloading condition described in the Introduction.

Color Code

(a)FPSO fully loaded and then emptied in 48 hrs. In this case only offloading is being considered

and no production of oil is taking place. This case may be needed in some emergency.

Table 2.8: Offloading schedule when FPSO is full


In the cases below both production and offloading have been considered simultaneously. This is

a normal operation of FPSO and not any contingency. The shuttle tanker arrives at 0Hr. and

leaves at 24 Hr.

(b) Day6 Type:

Table 2.9: Day 6 type offloading schedule

(c) Day11 Type:

Table 2.10: Day 11 type offloading schedule

All the above cases were checked for stability and results have been shown in Appendix2.2. All

the cases passed the stability regulations.

2.2.2 DAMAGE STABILITY:

Before checking damage stability it necessary to check MARPOL regulations, which restrict size

of tanks and compartment to restrict pollution in case of damage. If the tank sizes decided for the

FPSO fail to meet the requirements of MARPOL, then the tanks will have to be resized and this

directly affects the general arrangement of FPSO. The data presented in this report are final data

that have been obtained after a number of iterations taking into account both the owner’s

requirements and necessary regulations.

MARPOL CH.III: Requirements for minimizing oil pollution from oil tankers due to side and

bottom damage

(a) Regulation 22: Damage Assumptions


The extent of side damage (bottom damage not considered, as FPSO is not a moving

structure and will remain in deep sea all through its life) is given by:

Rule Longitudinal extent (lc

) 1/3L or 14.5m whichever is less (=>101.733 or 14.5)

14.5m

Transverse extent(tc ) B/5 or 11.5m whichever is

less(=>11.304 or 11.5) 11.304m

Vertical Extent(vc ) From Baseline upwards

without limit From bottom to top

(0-29.8m) Table 2.11: Extent of side damage

(b) Regulation 23: Hypothetical outflow of oil

The hypothetical outflow of oil in the case of side damage (O c) was calculated by

damage extents defined Reg.22.

O c= Wi + K iC i

Where

Wi = volume of wing tank damaged.

C i=Volume of centre tank, for segregated ballast tanks Ci =0. K=1-bi / tc; when bi is equal to or greater than tc Ki shall be taken equal to zero.

bi is the width of tank in meters under consideration.

The breadth and height of all cargo tanks in the FPSO are same. So for our case we have Ci =0

(as FPSO has segregated ballast tanks), K=0 (as bi (17m) > tc (11.304m). Tanks have different

lengths. From Table, we choose maximum length of tank, so that we get maximum hypothetical

outflow. This length is 24.55m. We assume two adjacent tabks have been damaged.

Wi = 24.55*27.3*17 = 11393.655m3

O c = 2*Wi = 2*11393.655=22787.31m3

From Regulation24 maximum value of Oc is 30,000 m3.

(c) Regulation 24: Limitation of size and arrangement of cargo tanks

(i)Cargo tanks shall be of such size and arrangement that the hypothetical outflow Oc ,

calculated in Reg. 23 anywhere in the length does not exceed 30,000m3 or 400(DW)1/3,

whichever is greater, but subject to a maximum of 40,000m3.

(ii)The volume of any one wing cargo oil tank shall not exceed 75% of the hypothetical

oil outflow. The volume of any centre tank shall not exceed 50,000m3. However, in

segregated ballast the volume of wing tanks situated between two segregated ballst tanks,

each exceeding lc in length, may be increased to the maximum limit of hypothetical oil

outflow provided tahta the width of the wing tanks exceed tc.

(iii)The length of cargo tanks shall not exceed 10m or one of the following values,


whichever is greater.

(i)Where no bulkhead is provided inside cargo tank: (0.5bi+0.1)L

(ii)Where centerline bulkhead is provided inside cargo tanks: (0.25bi+0.15)L

(iii)Where two bulkheads are provided inside the cargo tanks:

(1) For wing tanks: 0.2L

(2)For centre cargo tanks:

If bi/B is equal to or greater than one fifth: 0.2L

If bi/B is less than one fifth: 0.2L

• Where no centerline longitudinal bulkhead is provided: (0.5bi+0.1)L

• Where centerline bulkhead is provided: (0.25bi/B+.15)L

Application of Reg. 24

Since our FPSO has two longitudinal bulkheads, Reg. 24(iii), (iii) is used for determining the

length of cargo tanks.

Reg. applicable Min. Length of Wing

Tank

Min. Length of Centre

Tank

Max. Length of Wing Tank

Max. Length of Centre tank

Reg.24(iii),(iii) Lmin=10m Lmin=10m Lmax=0.2L=61.04m bi/B=17.32/56.52=.306 >1/5

So Lmax= 0.2L = 61.04m

The lengths of wing and centre cargo tanks chosen taking into account framing of FPSO into

account were 24.6m, 24.3m, 24.55m and 24m, none of which violate Regulation24.

Restriction on volume of tanks by Reg. 24(i) and Reg 24(ii)

The Reg. 24(i) and Reg. 24(ii) impose restriction on the volume of central and wing cargo tanks.

The tanks size must be such that it does not exceed hypothetical oil flow 30000m3. None of the

tanks designed for FPSO exceed this limit. Besides there is a restriction on size of wing tank, that

sets maximum size of wing tank at 0.75*Oc.

Length Type Volume of Tank Max. Volume of wing tank from hypothetical oil outflow=0.75 *Oc

Max. Volume of wing tank from hypothetical oil outflow=Oc

Wing Centre 24.60m 11416.86 m3 11631.76m3 22500 m3 30000 m3 24.30m 11277.63 m3 11489.90 m3 22500 m3 30000 m3 24.55m 11393.66 m3 11608.13m3 22500 m3 30000 m3 24.00m 11138.40 m3 11348.06m3 22500 m3 30000 m3

Table 2.12: Volume of wing and centre cargo tanks


Considering Reg. 22 on the damage assumptions we found that the damage of lc = 14.5m, tc =

11.5m can flood two sets of tanks on port or starboard side. Based on this thirteen damage cases

were made considering every set of adjacent tanks. The stability of the FPSO was verified by the

U.S. Navy criteria described both for static and dynamic stability. It is assumed that only

starboard side of FPSO gets damaged, this is because it is symmetric about its centerline,

therefore damage along port and starboard sides will give same results.The table shows the Static

Stability Result and Dynamic Stability in damaged case. The results are shown in Appendix 2.1.

Damage Case

Tanks Damaged Static Criteria

Dynamic Criteria

Dcase1 Slop ballast bottom 1.1 ,Slop ballast starboard,

Slop tank1, Ballast tank forwardmost

PASS

PASS

Dcase2 Slop ballast bottom 1.1 ,Slop ballast starboard, Slop tank1, Cargo10.1, Ballast starboard10, Ballast bottom10.1

PASS

PASS

Dcase3 Cargo10.1, Ballast starboard10, Ballast bottom10.1, Cargo9.1, Ballast starboard9, Ballast bottom9.1

PASS

PASS

Dcase4 , Cargo9.1, Ballast starboard9, Ballast bottom9.1,Cargo8.1, Ballast starboard8, Ballast bottom8.1

PASS

PASS

Dcase5 ,Cargo8.1, Ballast starboard8, Ballast bottom8.1,Cargo7.1, Ballast starboard7, Ballast bottom7.1

PASS

PASS

Dcase6 Cargo7.1, Ballast starboard7, Ballast bottom7.1 Cargo6.1, Ballast starboard6, Ballast bottom6.1

PASS

PASS


PASS

PASS


PASS

PASS


PASS

PASS


PASS

PASS


PASS

PASS

Dcase12 Cargo1.1, Ballast starboard1, Ballast bottom1.1, Cofferdam b/w ER & Cargo, Engine Room(ER), ER ballast starboard2, ER ballast bottom2.2

PASS

PASS

Dcase13 Engine Room(ER), ER ballast starboard2, ER ballast bottom2.2, Ballast Tank aftmost

PASS

PASS

Table 2.13: Damage cases Analysis

2.2.3 PROBABLISTIC DAMAGE ASSESMENT

The SOLAS regulations on subdivision and damage stability, as contained in part B-1 of SLAOS

chapter II-1, are based on probabilistic concept which takes probability of survival after

collision as a measure of ship’s in damaged condition. The probability of survival is determined


by the formula for entire probability as a sum of the products for the each compartment or group

of compartments of the probability that the space is flooded multiplied by the probability that

ship will not sink with considered space flooded. The aim of the rules is to provide ships (FPSO)

with a minimum standard of subdivision. The degree of subdivision to be provided was

determined by required subdivision index R.

R= (0.002+0.0009L)1/3 where L is in meters

The required subdivision index for the FPSO (L=305.2m) is 0.6516.

The attained subdivision index A was calculated by formula: A=PiS i .

The values of Pi and Si were calculated by method given in Appendix2.3.

For the required subdivision index, it is assumed that two adjacent set of tanks are completely

damaged. P1 is the probability that only tank set 1 is damaged. P2 is the probability that only tank

set 2 is damaged P12 is the probability that both tank set 1 and tank set 2 are damaged. The

damage assumptions are same as Reg.22 of MARPOL.

Since there is no horizontal subdivision above water line the Regulation 25-6-3 is not applied.

Therefore the FPSO midship section is equivalent to

Fig 2.2: Equivalent Cross Sectional View

The contribution of such a section to the attained subdivision index is given by:

dA= Pix[ R1 * S1 + (R2—R1)* S12 + (1-S2)*S123]

where

Pi accounts for the probability that only compartments or group of compartments under

consideration may be flooded disregarding any flooding.

S accounts for the probability of survival after flooding the compartments or group of

compartments under consideration including the effects of any horizontal subdivision.

Calculation of PiSi:

The probability of two adjacent tanks being damaged is given by:

Pi = P12-P1-P2.


Si= [ R1 * S1 + (R2—R1)* S12 + (1-S2)*S123]

Code for Probabilistic Damage Assesment: x1=0;%the distance from the aft terminal of Ls to the foremost %portion of the aft end of the compartment being considered x2=9.6; %the distance from the aft terminal of Ls to the aftermost %portion of the forward end of the compartment being considered Ls=305.2; % in m B=56.52; b=2.5; %measured from outer shell to longitudinal bulkhead. %Taken b=min{b1,b2,b3.....bn} E1=x1/Ls; E2=x2/Ls; E=E1+E2-1; J=E2-E1; if (E>0) Jdash=J-E; end if (E<0) Jdash=J+E; end Jmax=48/Ls; if (Jmax>0.24) Jmax=0.24; end a=1.2+0.8*E; if (a<1.2) a=1.2; end F=0.4+0.25*E*(1.2+a); y=J/Jmax; z=Jdash/Jmax; if (y<1) F1=y^2-y^3/3; F2=z^3/3-z^4/12; end if (y>=1) F1=y-1/3; F2=z^2/2-z/3+1/12; end p=F1*Jmax; q=0.4*F2*Jmax^2; pi=a*p; if (J>=0.2*b/B) if(b/B<=0.2) r=b/B*(2.3+.08/(J+0.02))+0.1; end if(b/B>0.2) r=0.016/(J+0.02)+b/B+.36; end


end if(J<0.2*b/B) if(b/B<=0.2) r=b/B*(2.3+.08/(J+0.02))+0.1; end if(b/B>0.2) r=0.016/(J+0.02)+b/B+.36; end r=J*(r-1)*B/(0.2*b)+1; end

Calculations of various parameters: In order to calculate S1,S2 and S12 GZmax and Heel Angle

was found by using Hydromax. The results have been tabulated below:

Calculation of S1

Case Full Load Partial load

Gzmax (m) Heel angle(deg) Sl Gzmax (m) Heel angle (deg) Sp S1

0.5(Sl+ Sp)

DCase1 3.424 3.4 1 5.852 0.9 1 1

DCase2 3.24 3.4 1 5.718 1.4 1 1

DCase3 3.302 3.4 1 5.837 1.1 1 1

DCase4 3.3 3.4 1 5.842 1.1 1 1

DCase5 3.3 3.4 1 5.847 1.1 1 1

DCase6 3.298 3.4 1 5.852 1.1 1 1

DCase7 3.297 3.4 1 5.857 1.1 1 1

DCase8 3.295 3.4 1 5.861 1.1 1 1

DCase9 3.293 3.4 1 5.866 1.1 1 1

DCase10 3.291 3.4 1 5.87 1.1 1 1

DCase11 3.3336 1.4 1 5.875 1.1 1 1

DCase12 3.367 -0.7 1 6.019 0.9 1 1

DCase13 3.274 -0.5 1 6.146 0.4 1 1

Table 2.14: Calculation of S1

Calculation of S2



0.5(Sl+ Sp)

DCase1 3.424 1.6 1 5.852 0.9 1 1

DCase2 3.275 2.7 1 5.57 2.3 1 1

DCase3 3.377 1.9 1 5.524 2.9 1 1

DCase4 3.377 2 1 5.551 2.6 1 1

DCase5 3.375 1.9 1 5.577 2.3 1 1

DCase6 3.372 1.9 1 5.6 2 1 1

DCase7 3.372 1.9 1 5.62 1.8 1 1

DCase8 3.367 1.9 1 5.639 1.5 1 1

DCase9 3.364 1.9 1 5.656 1.3 1 1

DCase10 3.36 1.9 1 5.671 1.1 1 1


DCase11 3.405 1.9 1 5.681 0.9 1 1

DCase12 3.368 -0.2 1 5.915 2.1 1 1

DCase13 3.274 0 1 6.146 1.1 1 1


Calculation of S12



0.5(Sl+ Sp)

DCase1 3.424 1.6 1 5.852 0.9 1 1

DCase2 3.365 2.6 1 5.67 2.4 1 1

DCase3 3.578 1.8 1 5.718 3.2 1 1

DCase4 3.581 1.8 1 5.77 2.8 1 1

DCase5 3.581 1.8 1 5.797 2.4 1 1

DCase6 3.581 1.8 1 5.81 2.1 1 1

DCase7 3.579 1.8 1 5.818 1.8 1 1

DCase8 3.576 1.8 1 5.826 1.6 1 1

DCase9 3.571 1.8 1 5.835 1.3 1 1

DCase10 3.565 1.8 1 5.847 1.1 1 1

DCase11 3.615 -0.7 1 5.862 0.8 1 1

DCase12 3.506 -1.8 1 5.992 0.6 1 1

DCase13 3.274 -0.5 1 6.146 0.4 1 1


Calculation PiSi

Table 2.17: Calculation of PiSi


The attained subdivision index(0.7517) > required subdivision index(0.6516). Therefore the

FPSO design satisfies probabilistic damage assessment criteria.

3) Wind and Current Loading:

Of primary concern in holding a ship stationary is opposing forces resulting from wind and

current action. Forces, arise from currents, are essentially irresistible forces; the resulting vertical

movement of the FPSO must be allowed for and can’t be opposed. Similarly, the wave forces

acting on a stationary ship are essentially oscillatory in nature; they can be minimized by the

reorienting the ship or by detuning its natural response but little can be done to oppose the

oscillatory ship motions resulting from wave actions. Thus, the brief discussion herein of the

environmental constraints involved in a mooring or a dynamic positioning system design will be

limited to wind and current forces, neither waves nor tides.

The wind and current forces have been calculated for 2 extreme drafts: (a) Full Load draft and

(b) Ballast Load draft because in full load case the wind force will be minimum while the current

force will be maximum while in ballast load case the wind load will be maximum due to huge

exposed area to the wind and current load will be minimum. So we’ll look towards the case in

which net load will be maximum.

Ship Dimensions 305.2m!56.52m!29.8m Full Load Draft 22 m

Ballast Load Draft 7.895 m Table 3.1: Dimension and Extreme Drafts.

3.1 Wind Force Calculations: Air moving across a water surface has a varying velocity with

altitude due to the interaction between the surface and the air mass. Saunders (1957) gave a

conclusion that the most consistent average of various data was one where the velocity varied as

the fifth root of the height above the surface. This is expressed as:

Where : airstream velocity at an height ‘h’ : airstream velocity at some standard height ‘ho’ And the Wind force is expressed in the terms:

mass density of air the wind velocitythe area with all terms in consistent dimensions


a constant drag coefficient The standard used for wind velocity measurements over ground is a height ho of 10 m. To calculate the wind force on a projected strip of a ship of length L and height h2-h1, the following equation is used;

When calculating wind forces and moments for any mooring and dynamic positioning application it is usually desirable to determine the force distribution with the wind at various angles to the ship and also the yawing moment that the wind can apply as a function of wind angle. First thing is to calculate the longitudinal wind forces (at angle of attack ) and transverse wind forces (at angle of attack ). The above water areas to be included are all of those structures that the wind will impinge upon. After calculating the wind forces for longitudinal and transverse directions, we have calculated the wind force at each angle of attack from 0° to 180° varying at each 10° off the bow. These calculations were done using the Flow forces and Centre Multipliers (Appendix 3 and Table 3.1), data taken from ’The Ship Design And Construction, by Taggart’. The detailed wind force calculations have been shown in Appendix 3: The calculation results are as follows:

Load Case Draft(m) Net Wind Force (kN) Full Load 22 1262.707 ( at 90°) Ballast Load 7.895 1780.814 (at 90°)

Table 3.2: Wind Force results for extreme drafts 3.2 Current Force Calculations: The movement of body of water in which a ship is moored or dynamically positioned applies a downstream force to the hull that must be counteracted by the mooring system to the extent that the ship does not move outside its boundaries. When secured to a SPM, the boundaries are often established to allow the ship to move around to a heading where the current has a minimum effect, and thus the mooring system can be designed for this adaption to minimal environmental forces. As in the calculation of wind effects on the above water structure, the current forces have been calculated for any direction of flow relative to the hull and similarly the centre of application of these forces has been calculated. For a ship type hull, without locked propellers, the axial resistance to a bow-on current is calculated as:


And transverse resistance to beam-on current is calculated as:

Where; mass density of water = maximum section coefficient mean water body length mean draft current velocity The detailed current force calculations have been shown in Appendix 3: The calculation results are as follows: Load Case Draft(m) Net Current Force (kN) Full Load 22 2953.466 ( at 90°) Ballast Load 7.895 1205.893 (at 90°)

Table 3.3: Current Force results for extreme drafts. 3.3 Steady Wave Loads:

The Steady wave loads have been approximated by the Added Resistance when FPSO is exposed

to 100 year sea conditions. Since the FPSO is turret moored, it is weathervaning. Thus, waves are

always at zero degrees to the FPSO.

Added Resistance:1. Full Load Case (Draft =22m)

Fig 3.1: Added Resistance RAO for full load case


2. Ballast Load Case (Draft =7.895m)

Fig 3.2: Added Resistance RAO for ballast load case

3.4 Net Environmental Load:

Case 1: Full Load Condition (Draft=22m)

Max Force (Wind+ Current) = 4216.174 kN at 90°

Steady Wave Force = 2195.54 kN at 0°

Net Steady Force (Wind+ Current+ Wave) = kN

= 5185.95 kN


So, The Net Steady Environmental Load is 5185.95 kN acting at off the bow.

Case 2: Ballast Load Condition (Draft= 7.985m)

Max Force (Wind+ Current) = 2986.70 kN at 90°

Steady Wave Force = 4182.67 kN at 0°

Net Steady Force (Wind+ Current+ Wave) = kN

= 5139.56 kN

So, The Net Steady Environmental Load is 5139.56 kN acting at off the bow.

Since the Full Load Case provide greater Environmental Load, we take 5185.95 kN as our

Design Load for Mooring System Design.

4. Strength and Structural Design – General

The design of the ship structures is highly regulated by the International Classification Societies.

In order for a ship to be approved for construction, it must meet the standards of classification

society. The objective of the project is to store oil in the FPSO after extraction from the oil field.

So we have chosen a double hull oil tanker shape to serve this purpose. This vessel is built to

meet the rules and regulations set forth by American Bureau of Shipping (ABS)-rules for

building and classing Steel Vessels (Double Hull Tankers). The scantlings of the structure can be

calculated only from the ABS rules for specific vessel i.e. double hull tankers. But since the

FPSO is positioned at a particular position on a long term basis, the environmental loading at that

site should be taken into account while doing calculations. Hence, the structural design was

modified accordingly to reflect the site-specific environmental loads. The calculations were done

using softwares HYDROMAX and MATLAB.


4.1 Work Flow:-

The first step is to determine a midship section with certain number of girders, stiffeners and

other members at their approximate positions. A midship section with double bulkheads was

considered.

Then the minimum thickness of plates and other primary support members were calculated

according to the rules given in ABS for double hull tankers (Section 8/2.1.5) which is given in

Appendix IV, Table 4.1. With the midship section with us, we calculated the vertical neutral axis

of the midship taking into account the basic values obtained. A program was formulated in

MATLAB to determine the vertical neutral axis of the midship section. Thereafter the net

vertical and horizontal hull girder moment of inertia was calculated.

The ship model was created in Hydromax with the tanks at appropriate positions. Since for a

FPSO the environmentally induced loads are dominated by waves, past 100 years wave data was

collected from the wave atlas for the specific site i.e. Usan field. For the 100 years sea spectrum,

the significant wave height (Hs) was 5 m. Then H1/10 was calculated using the formulae H1/10 =

1.273 Hs. Then a wave having wavelength equivalent to length of the vessel and wave height as

calculated before was imposed on the ship model in hydromax as if the ship is statically poised

on it. The maximum vertical bending moment and shear force were determined for the

corresponding load cases. This bending moment value was compared with the one calculated

from ABS rules for double hull tankers for each load set and the maximum of the two is taken

into account for further calculations.

Fig 4.1: Wave Form


Next the calculations were done for the different structural members by considering the

respective load sets given for each of them in the ABS rules (Section 8/Table 8.2.7) which is

given in Appendix IV, Table 4.5. For each load set, the specifications on load component, design

load combination, acceptance criteria and other parameters are mentioned as in ABS rules (Table

8.2.8) or Appendix IV, Table 4.6 of our report. The static and dynamic load components were

calculated from the ABS rules and their significance are given in Appendix IV, 4.2. For each

structural member various load sets were considered and thickness calculations were done. Out

of those, the maximum value was chosen and that was assigned as the minimum thickness value

for that member.

After thickness calculation of all the members, the minimum section modulus for stiffeners was

determined from ABS (Section 8/Table 8.2.5) or Appendix IV, Table 4.3 and Table 4.4 of the

report. Then the size of the stiffeners for the corresponding section modulus was determined

from the Bureau Veritas rules for steel vessels.

With the minimum thickness and size of stiffeners calculated, the new vertical neutral axis of the

midship was determined. The above steps were repeated and iteration resulted in final thickness

values for the members. The material class and grades of steel used in various positions of a

double hull oil tanker were also taken into account as in (Section 6/Table 6.1.3 and Table 6.1.4)

of ABS rules or (Appendix IV, Table 4.8) in our report. MATLAB was used for calculation of

neutral axis of midship, various load components, thickness, and section modulus and weight

estimation. The programs made for the calculation of all the above elements are shown in

Appendix 4.5.

With the obtained neutral axis and thickness values the stress level at deck and keel were

calculated. These stress level should be within limits for the type of steel that is used. If stress is

not within limits then thickness are changed accordingly but keeping in mind the minimum

values. Numbers of iterations are made varying the thickness of the plates. Once the shear stress

at deck and keel are within limits, the thickness values are finalized for the structural members.

After the scantlings are finalized, the weight per unit area of midship section was found. This is

extrapolated forward and aft of amidships. Hence, the total steel weight of the ship was

determined. This should be comparable to the steel weight estimation in preliminary design.

Finally, 10% of the calculated weight was taken as the margin for the brackets, web frames,

floors, transverse bulkheads etc.

4.2 Load Calculation:-

The vertical bending moment at amidships was calculated by using ABS rules for double hull

tankers and from the 100 year wave data. The values obtained from all the above two methods

were compared and the maximum of them was selected for further calculations.


1. Using the ABS rules for double hull tankers, the still water and wave bending moment at

amidships was determined.

• The minimum hull girder hogging and sagging still water bending moment at amidships for sea going and harbor operations were calculated from (Section 7/2.1.2) of ABS rules for double hull tankers.

These values are given below:-

Hogging:-

Msw-hog-mid = 0.01CwvL2B (11.97-1.9Cb) = 5.682 X 106 kNm

(Where Cwv is the wave coefficient and is equal to 10.75)

Sagging:-

Msw-sag-mid = -0.05185CwvL2B (Cb+0.7) = - 4.93 X 106 kNm

Comparing the above two values we finalize the still water bending moment at amidships to

be, Msw-sea = 5.682X 106 kNm

The still water bending moment at amidships for harbor condition was calculated.

Msw-harb = 1.25 Msw-sea = 7.05 X 106 kNm

• The vertical and horizontal wave bending moment at amidships were also found out from the ABS rules (Section 7/3.4.1 and 3.4.2 respectively) or (Appendix IV, 4.1) of our report. The vertical wave bending moment for hogging and sagging case are given as follows:-

Mwv-hog = 10.54 X 106 kNm

Mwv-sag = - 10.46 X 106 kNm

The horizontal wave bending moment, Mh was calculated for all the load sets:-

Load cases Moment (kNm)

Scantling case 11 X 106

Cargo only 8.52 X 106

Ballast only 3.279 X 106

Table 4.1: Horizontal Wave Bending Moment

2. The bending moment calculations were also done on the basis of 100 year wave data.


A wave of wavelength equivalent to the length of the vessel was assumed, whose height was

taken to be equal to H1/10 = 6.36 m. This wave was imposed on the ship and the bending

moment calculations were done for both hogging and sagging case.


Scantling case Mwv-hog = 22.8 X 106

Mwv-sag = 7.11 X 106

Cargo only Mwv-hog = 5.75 X 106

Mwv-sag = 22.17 X 106

Ballast only Mwv-hog =11.5 X 106

Mwv-sag = 5.36 X 106

Table 4.2: Wave bending moment from 100 yr data

The graphs are shown in Appendix 4.3.

4.3 Results:

The still water bending moment was finalized as per the ABS rules for double hull tankers.

Still water bending moment at amidships for sea going operations:

Msw-sea = 5.682X 106 kNm

Still water bending moment at amidships for harbour condition:

Msw-harb = 7.05 X 106 kNm

For vertical wave bending moment, comparisons were done for all the above 3 methods. The

maximum among them was finalized for further analysis.


Scantling case 22.8 X 106

Cargo only 22.17 X 106

Ballast only 11.5 X 106

Table 4.3: Design bending moment

4.4 Structural Components:

Keel Plate:-

The minimum thickness for keel plating from Table 4.1 was found to be 14.6 mm. The keel plate

breadth is only affected by the length of the vessel. The calculated breadth was 2.326 m (using

the formulae b=800+5L mm from ABS rules for double hull tankers Section 8/2.2.1) and the

installed breadth is 2.5 m. The thickness of the keel took into account the material strength,


corrosion factor and stress factor. Corrosion addition was determined from the Table 4.9 and

Figure 4.1. The corrosion addition was taken as 3.0 mm. The calculated thickness was 22mm.

Bottom Plate:-

The minimum thickness for bottom plating from Table 1 was found to be 12.65 mm. Next using

the formulae in Table 4.2 we calculate the thickness for different load sets. Pressures

corresponding to each load set were calculated using the Tables 4.4, 4.5, 4.6. The dynamic wave

pressure (Pwv-dyn) and static sea pressure (Phys) for load set 1 and 2 were calculated. The dynamic

tank pressure (Pin-dyn) and static tank pressure (Pin-tk) for load sets 7 and 8 were also calculated.

Taking into account the load combination (Appendix IV, Table 4.7) and acceptance criteria for

each load set minimum thickness were calculated using the formulae in Table 4.2 as follows:

Load set Load component (KN/m2) Thickness (mm)

1 274.7 19.8

2 249.25 18.9

7 25.55 8.0

8 258 19.3

Hence the minimum thickness of bottom plating was finalized as 19.8 mm. Corrosion additions

were taken into account.

Side Shell:-

The minimum thickness for side shell form Table 1 was found out to be 13.6 mm. Same load sets

were considered as bottom plating for calculation by referring the Table 4.4, 4.5, 4.6. The

pressures were calculated for various positions. Static and dynamic pressure for region below the

load waterline was considered.


1 220.742 17.1

2 149.4 16.0

7 27.66 8.0

8 157.9 15.5

Considering the corrosion additions, the minimum thickness of side shell plating was finalized as

17.1 mm.

Inner Bottom Plate:-

The minimum thickness was calculated as 10.6 mm from Table 4.1. Next different load sets were

considered to calculate thickness. For load case 3 in Table4.4, the static and dynamic cargo tank

pressure were calculated and the summation was the total pressure considered for calculation.


But for load set 5, summation was made for static and dynamic pressure for ballast tanks. The

thickness was calculated for all the load sets and load combinations by using the Table 4.2.


3 336.87 23.0

4 324.64 21.5

5 299.64 19.0

Considering the corrosion additions, the minimum thickness of inner bottom plating was

finalized as 23.0 mm.

Inner Side shell:-

The above procedure was repeated for side shell thickness calculation. The minimum thickness

from the Table 4.1 was calculated as 10.6 mm. For the load set 3, pressure on the side shell was

considered from the cargo tank region and for the load set 5 and 6 pressure from ballast tanks

was taken into account while calculation.


3 231.72 17.8

4 307.3 21.6

5 235.76 18.0

The minimum thickness of the inner side shell was finalized as 21.6 mm.

Deck Plate:-

Initial deck thickness was calculated from Table 4.1. It was found to be 10.6 mm. The thickness

calculation for deck plating was done both for weather deck condition and distributed or

concentrated load condition. When weather deck is considered, for various load sets like

scantling, cargo only and ballast cases, the sea pressure, cargo pressure or only ballast water

pressure is calculated respectively. But since the thickness we obtained was very less,

concentrated load condition was also taken into consideration. The arrangement of modules on

the top deck is known. The size and weight per area of each module is known. The weight per

area of each module gives the pressure and the maximum pressure is considered and is added

with static pressure to give the total pressure. For load case 10 only the concentrated load

pressure of the modules was taken and thickness was calculated. The final thickness of deck was

finalized as 17.5 mm.


1 34.3 12.2

3 40.67 13.4

9 253.43 17.5

10 181.22 16.3


Longitudinal Bulkhead:-

The minimum thickness was determined as 10.6 mm from Table 4.1. Then the cargo only case

was considered and the minimum thickness was calculated. Two cases were evaluated- inner

tank empty, outer full and outer tank empty, inner full. The dynamic and static pressure of the

tanks were calculated and their summation yields the total pressure on the bulkhead. The

corrosion addition made is 2.5 mm.


3 216.95 16.4

4 307.3 21.0

11 210 19.1

Girders:-

The thickness of double bottom centerline girder and other girders were calculated using the

Table 4.1. The thickness of centerline girder is 13.13 mm and other girder thickness was 11.6

mm. Then the thickness was calculated for ballast load set where pressure from one side of

ballast tank was taken into consideration. For each girder pressure on that due to the water on

one side was calculated and this pressure was used to further determine the thickness of the

girders using Table 4.2. The corrosion addition was also considered from Figure 4.1.

Centerline Girder:-


5 387.17 21.3

6 307.29 20.6

Girder under bulkhead:-


5 368.78 21.1

6 307.29 21.0

Side girders:-


5 350.61 20.6

6 307.29 21.2


Side Shell Girder:-

During this calculation, due to different vertical heights of the girders the pressure on each girder

is different. Hence the thickness comes out to be different. The maximum thickness out of all

those calculated, was finalized and assigned as the scantling of the side shell girder for each load

case. And out of all the load cases, the maximum thickness obtained was finalized as the

minimum thickness required for the side shell girder.


5 223.22 16.4

6 208 17.3

11 185.02 15.0

Bottom Longitudinal:-

The section modulus requirement was calculated by determining the effective span of the

longitudinal and longitudinal length. The span for these longitudinals was taken as 1 m and the

effective length as 3.4 m, the distance between major frames. The pressure corresponding to the

maximum thickness for any load set was taken into consideration. This pressure was used in

calculation of the section modulus using Table 3. The factors considered for the calculation were

yield stress of material, distance from neutral axis and hence hull girder bending stress. The

section modulus for bottom plating and inner bottom plating are:

Bottom plating - 1085.7 cm3

Inner bottom plating- 1331.4 cm3

Side Longitudinal:-

The side longitudinal section modulus requirement was identical to the one above. The pressure

used was the same as in calculation of general side plating thickness. The allowable stress

consisted of the material factor, stress factor, distance from baseline to neutral axis and distance

from base to the point in the question. The section modulus was found to be 974.3 cm3. For inner

side shell pressure from cargo region was taken into consideration and the section modulus found

out to be was 1041.7 cm3.

Deck Longitudinal:-

The pressure taken into consideration was the same as in thickness calculation. The bending

stress at deck is considered which in turn depends on the distance between the vertical neutral

axis and the deck. The section modulus calculated was 1030.9 cm3.


Longitudinal Bulkhead Section Modulus:-

The same procedure was implemented as above. Pressure considered was the same from the

thickness calculation. With the material yield stress known the section modulus was determined.

The location of the stiffeners was also taken into account as in side shell stated above. The span

was determined to be 1.0 m since these longitudinals would tie into the longitudinal framing

system of main deck and bottom structure. The section modulus hence calculated was 1041 cm3.

4.5 Final Analysis:

The thicknesses of all the members of the midship section were determined. From the section

modulus at different positions we decided the type and size of stiffeners to be used in the

midship section. For the sake of standardization the stiffeners used in double bottom region were

chosen to be bulb sections of 370x13 mm2 and the stiffeners for side shell, longitudinal bulkhead

and deck were chosen to be 340x12 mm2. The new position of the neutral axis was found out.

After that the stress level at deck and keel was calculated which depend on the distance between

the neutral axis and deck or keel. If the stress level is not within permissible limits then further

iterations were done. The scantlings are changed accordingly but keeping in mind the steel grade

requirement at a specific position. Sidewise the weight per area of the midship is also calculated

and it is extrapolated to find the overall steel weight of the ship. This weight that we have

calculated should be comparable to the weight estimated while doing preliminary design. With

all these factors taken into account we decided the final scantlings of the midship section as

given in the Table below. The final neutral axis of the midship section was determined as 13.55

m from bottom. The stress at deck was calculated to be 172.41 N/mm2 and at keel it was found to

be 143.75 N/mm2, both are within permissible limits. The steel weight of the ship was calculated

to be approximately 23637 tonnes.

Structural Components Minimum Actual

Keel plate breadth (mm) 2326 2500

Keel plate thickness (mm) 22 35

Bottom plating thickness (mm) 19.8 30

Side shell thickness (mm) 17.1 28

Inner bottom thickness (mm) 23 32

Inner side shell thickness (mm) 21.6 30

Deck plate thickness (mm) 17.5 40

Longitudinal bulkhead (mm) 21 28


Girder below long. bulkhead (mm) 21.1 28

Other double bottom girder (mm) 21.2 26

Side shell girder thickness (mm) 17.3 28

Shear strake thickness (mm) 20 40

Bottom plate section modulus (cm3) 1085.7 1424

Inner bottom section modulus (cm3) 1331.4 1446

Side shell section modulus (cm3) 974.3 1096

Inner side shell section modulus (cm3) 1041.7 1114

Long. bulkhead section modulus (cm3) 1041 1096

Deck long. Section modulus (cm3) 1030.9 1169

Table 4.4: Final Scantlings

Midship Section

Fig 4.2: Midship Section


5. Mooring and Station Keeping: The ship-shaped vessels used as FPSOs generally have the advantages of large oil storage capacity and high stability margin. The vessel motions, however, in both wave energy spectral period range (3-25 seconds) and slowly varying period range (>50 seconds) are inevitably large due to the excessive water plane area of a ship-shaped vessel. In addition, the high length-to-beam ratio of a ship-shaped vessel necessitates the vessel be able to weathervane into the prevailing environmental loads due to wind, current and waves in order to minimize the loading on the mooring system. Therefore, the critical design issues of a mooring system for an FPSO are:

• Line dynamics due to six degrees of freedom wave frequency vessel motions (in surge, sway, heave, roll, pitch and yaw),

• Low frequency vessel motions in surge, sway and yaw, and

• Effects of non-collinear environments of wind, current and waves on the responses of the vessel and its mooring system.

From the designer’s point of view, there are options in the selection of vessel size, design pretension, turret location, mooring pattern, line configuration and anchoring point. The proposed design options can reduce the possibility of progressive failure of a mooring system under extreme design events. This in turn will enhance the reliability of a mooring system designed for FPSOs operating in geographic areas with tropical environments. 5.1 Design Environmental Criteria:

The mooring system of an FPSO is usually designed to survive in a 100-year return period event in a combination of wind, current and waves for a specific project site. Figure 5.1 shows major oil producing offshore areas of the world, where FPSOs are anticipated.

Fig 5.1: Major Oil Producing Offshore Areas Worldwide

In selecting the design environmental criteria for a vessel allowed to weathervane, special attention is to be given to the non collinear environments of wind, current and waves and the design wave period range. This is due to the sensitivity of the environmental mean loads to the directionality of environments off the bow for a ship-shaped FPSO vessel with a large length-to-


beam ratio. In addition, the wave-induced vessel motion responses are also very sensitive to wave directions relative to the vessel and the design wave periods. 5.2 Vessel Design Characteristics:

The vessel size is usually dictated by the oil storage capacity and the topside layout as the functional requirements of an offshore project. The physical dimensions of a vessel and its general arrangement of deck and hull will in turn determine the wind, current and wave forces and moments acting on the vessel. The hull shape and geometry of a vessel together with its mass properties in terms of the center of gravity location and radii of gyration in roll, pitch and yaw will define the hydrostatics and motion response characteristics. Subsequently, these vessel design characteristics will be used to determine the mooring system responses under the design environmental conditions. In selecting the vessel size it is important to keep the natural periods in surge and sway for the total system (vessel with its mooring system) longer than at least three times the design wave spectral peak period. This will minimize the possible dynamic amplification of total system responses under the effects of wave frequency energy in the period range of 3 to 25 seconds. To keep the natural periods in pitch and roll longer than the design wave spectral peak period is also desirable for reducing wave frequency motions of an FPSO. In most cases, this is, however, difficult to achieve. Bilge keels have, on occasion, been introduced to dampen roll and pitch motions. 5.3 Vessel Offsets and Design Pretensions:

Under the design environmental conditions of wind, current and waves, the total vessel offset and motions consist of three components:

1. Mean steady offset and equilibrium vessel heading due to static mean forces and yaw moment of wind, current, and

2. Low frequency motions due to slowly-varying wind and wave drift forces, and 3. Wave frequency motions due to first order wave excitations.

There are mooring line tensions corresponding to each of these vessel-offset positions, headings and motions. The mean offset and low frequency motions are a function of the mooring system stiffness. The mooring system stiffness can be adjusted by varying the initial design pretension of a mooring system under no environmental loading. The higher the design pretension and the mooring system stiffness the smaller the vessel offset will be. Usually the riser design will dictate the vessel offset criteria for the mooring system design. The unnecessarily high design pretension, however, will impose larger total line tension and thus result in lower safety factors for a mooring design.


5.4 Analytical Procedure:

For FPSO mooring systems, both vessel/mooring system and line dynamic analyses are to be performed. A simplified method of line dynamic mooring analysis is outlined in following Flow diagram.

Fig 5.2: Mooring analysis flowchart 5.5 Mooring Line Configuration:

The conventional mooring lines generally consist of the combination of chain and wire rope. Submersible buoys and/or clump weights may be introduced along a mooring line for various design considerations. As shown in following figure in deep water (greater than 300m), the wire rope is used for most of the suspended portion of a mooring line to increase the stiffness and reduce the top tension of a mooring line. In ultra deep waters (greater than 2000m), even the


conventional chain-wire combination will become too heavy and too soft in horizontal stiffness to resist environmental loads.

Fig 5.3: Deep water mooring line configuration. 5.6 Mooring System Evaluation:

To determine the mooring line tensions and anchor specification, we need to calculate the Environmental Loads. 5.6.1Environmental Loads: Environmental loads have been calculated for 2 extreme drafts:

1. Full Load draft(22 m) 2. Ballast draft(7.895 m)

Once the environmental loads for these 2 drafts have been calculated, we design the mooring line

for maximum environmental loads. Environmental Loads for these 2 drafts are as follows:


1. Full load Draft (22m):

a. Wind Loads = 1262.707 KN

b. Current Loads=2953.466 KN

c. Wave Loads=2195.54 KN

d. Net Loads = 5185.95 KN at 65°

2. Ballast Draft (7.895m):

a. Wind Loads = 1780.814 KN

b. Current Loads=1205.893 KN

c. Wave Loads=4182.67 KN

d. Net Loads = 5139.56 KN at 35.5°

Thus our design load will be the environmental load in Full load conditions.

5.6.2 Mooring System Design: (Appendix: V)

FPSO is Turret Moored. We assume that the mooring line configuration is 12- leg Catenary (6*2). Water depth is 850 m. The maximum possible deflection as limited by Riser system is 20% of the water depth. The natural period of mooring system = 200 sec (Table: 5.7) From the Surge model of turret moored FPSO:

Assuming the added mass to be equal to 25% of the total mass, this equation leads to a max. desirable stiffness. M=386546 tonnes (Displacement of FPSO) a= 96636.5 tonnes

In order to avoid the excessive motions the designer always wishes to limit the displacement of the system. Suppose the risers limit the acceptable deflections to 20% of the water depth. This will result in minimum stiffness requirement for the system. The steady force taken by the mooring system= 5186 KN


We are considering 3 different combinations of chain-and-wire rope to find out the most suitable mooring line. Case1: Only Chain Case2: Chain-Wire rope-Chain (depth wise 100m-650m-100m) Case3: Chain-Wire rope-Chain (depth wise 100m-500m-250m) Mooring Line Tension Analysis has been shown in Appendix: 5 The results clearly indicate that combination of chain and wire rope in case3 gives minimum working tension and minimum weight of mooring line. 5.7 Anchoring System: The anchoring points fixed to the seabed are the critical part of a mooring system for keeping an FPSO on location. Depending on soil conditions and the required performance, there are various types of anchors that can be selected. There are basically two types of anchors: • Conventional drag embedment anchors, and • Anchors, which are designed to resist vertical loads, such as pile, suction and vertically loaded plate anchors (VLAs). There are concerns about VLAs designed to take vertical loads. These anchors may exhibit complete loss of their holding capacity after pulling out from the seabed. This is in contrast to the Conventional drag embedment anchors, which can still retain considerable amount of holding capacity even after some movement under the environmental extremes. In addition, there will always be some uncertainties involved in the analysis of the site-specific soil conditions. Therefore, ABS (Huang and Lee, 1998) requires higher safety factors for ultimate design holding capacities of VLAs as compared with conventional drag embedment anchors. The safety factors of both types of anchors are listed below for comparison: (a) Intact Design Environmental Condition (1) VLA Anchors - 2.0 (2) Conventional - 1.5 (b) One- line Broken Design Environmental Condition (1) VLA Anchors - 1.5 (2) Conventional - 1.0 Conventional drag embedment anchors are considered to have some consequential advantages over VLAs. In case the design environmental criteria would be exceeded and causing the anchor to move, these drag anchors still can retain most of their holding capacity. In addition, with anchor movement the grouped mooring lines will adjust line tensions among themselves to reduce the peak line tension of the most-loaded line.


5.7.1 Anchor Design: The efficiency of an anchor is defined as the ratio of Anchor’s holding capacity and Anchor’s weight. The following equation represents the anchor efficiency.

Where E= efficiency W= weight of anchor in air (kN) P= ultimate holding capacity (kN)

British Standard 6349, Part 6: 1989 cites the following anchor system efficiencies:

Anchor Type Efficiency in poor soils, silts and soft clay

Efficiency in good soils, sand and firm clay

Deadweight anchors 0.3 0.5 Stockless anchors 2.0 5.0

Stock anchors 5.0 10.0 High holding power anchors 10.0 30.0

Table 5.1: British Standard-6349 anchor system efficiencies.

The anchor system also is subjected to dynamic loads as the ship surges, sways and yaws in adverse weather and is buffeted by wave action. A Z-factor multiple is applied to approximate the anticipated force increase required in a static analysis. This factor, based on Navy experience, uses a value between 1.25-1.50 for small ships with fine lines; 1.50-1.70 for larger more fully shaped ships; 1.75-2.00 for cargo ships and auxiliaries with more blunt shapes. After selecting the Z-factor the horizontal component of the anchor line tension becomes:

Where; = total wind and current load = total resistance corrected for dynamic forces

Thus, Required anchor weight (in air) =

In our case;

FR= 4698.266 kN

Z=2

>> H=9396 kN

Taking the ‘Stock Commercial Anchors’ and soil

conditions to be firm;

E=10

>>W=95.78 tonnes


5.8 Turret Concept: Spread Moorings, on which a vessel heading angle is essentially fixed, are suitable for semi-submersible which are not too sensitive to incident wave direction. However tankers are very sensitive to wave direction so in open water, unless the climate is very mild or the waves always come from the same direction, it is usually best to allow a tanker to weathervane around the mooring. This will reduce mooring forces and vessel roll. It requires the mooring to be attached to a single point, usually at the bow, hence the term Single Point Mooring or SPM. The many types of SPM involve mooring the tanker to a loading buoy or column. Important design considerations are:

(1) the avoidance of collision between tanker and its mooring column or buoy etc. (2) the control of mooring system forces, (3) the control of deflections, in order to avoid damaging the oil loading pipes and risers, (4) the need or otherwise for a launch to assist with mooring and hose connection.

We have employed Turret concept for SPM.

There are mainly three types of commonly used Turret systems:

1. External Raised Turret

2. External Bottom Clamped Turret

3. Internal Turret

The merits and drawbacks of these systems are discussed in following table:

External Raised External Bottom Clamped

Internal

The hull integrity is least affected and the integration to hull is most straightforward.

The hull integrity is not significantly affected and the integration to hull is relatively simple.

The hull is to be modified to have a moon pool with necessary reinforcement. There is a loss of cargo space.

Risers The number of riser depends on the chain table and bearing sizes. Typical limit is around 20.

Usually has small column diameter to accommodate a limited number of risers.

Up to 47 risers has been designed and concept of large internal turret to accommodate up to 100 risers has been proposed.

Bow Interference

Require an extended cantilever to avoid anchor leg and hull interference. Sometimes, the bow has to be cut.

None None


Installation The installation is straightforward because the turret is above water and moorings and risers can be pulled in along their natural angles.

The pull in of the anchor legs can be difficult because of the pulling arrangement and the limited space available.

The installation needs careful planning to route the pulling of the anchoring legs and risers.

Wave Slamming

Usually avoided by positioning the turret above wave crest.

The wave slamming load is to be accounted for in the design.

The turret is inside the moon pool and thus protected.

Vertical motion

High because the turret is extended over the bow.

High because the turret is at the bow.

Reduced as the turret position is closer to the mid-ship.

Bearing Loads

The bending moment is high because the chain table is extended like a cantilever below the bearing. The mooring and riser horizontal and vertical loads can cause large bending moment at the bearing.

The bearing horizontal load and bending moment is significant reduced because of the lower support.

The bearing horizontal load and bending are significantly reduced because of the lower support and upper elastomeric support.

Table 5.2: Comparison amongst the 3 types of turret systems.

5.8.1 Function of a Turret System: The turret system performs four main functions in a typical FPSO: • Maintaining the vessel on station through single mooring. • Allowing weathervaning or rotation of the vessel to adjust to climate conditions. • Fluid transfer from the risers to the process plant. • Providing transfer of electrical, hydraulic and other control signals.

Fig 5.4: The generic sub-systems within a typical turret system.


Figure 5.5: Schematic diagram showing the interfaces for an FPSO turret and the areas of internal

and external load transfer. An FPSO turret system contains the following three main systems: • The turret itself. • A fluid transfer system, usually a multi-path swivel to transfer production fluids to the process Plant on the vessel. • Turret transfer system, intermediate manifolding, which provides a link between the turret and the FTS. The TTS is often referred to more generally as the turnable or turnable manifolding. 5.8.2 Weathervaning: An advantage of a turret system over other options for floating installations such as spread-mooring is that it allows the vessel to rotate and adopt the optimum orientation in response to weather and current conditions. This rotation of the vessel about the turret is known as weathervaning. In most cases the vessel can freely rotate through 360 degree; known as free weathervaning. If the rotation is restricted this is described as partial weathervaning. The latter is the case for turrets with a drag chain for fluid transfer, which can only rotate +/- 270 degrees in either direction. 5.8.3 Parts of a Turret System: The turret system is considered in the following four parts:


• Turret (T): This provides the single-point mooring and allows weathervaning of the vessel. It includes the turret shaft, turret casing, main and lower bearings and the mooring spider. • Fluid Transfer System (FTS): This is typically a multiple swivel assembly. It transfers the process fluids and other signals from the turret to the process plant on the vessel. It is positioned above the turret and linked via the turret transfer system. • Turret Transfer System (TTS): This refers to the intermediate manifolding linking the turret and the FTS. Positioned on a turnable on top of the turret. It rotates with the turret. It is otherwise referred to as the turnable or turnable manifolding. • Interfacing systems (IS): This includes swivel access structure, mooring lines and flexible below the turret and other ancillary equipment. 5.8.4 Interfaces: There are four main external boundaries separating the turret system from the vessel. These are important from a safety and operational standpoint as they are all points of load and/or hydrocarbon transfer: • Fluid Transfer System to ship (to process plant). • Main turret bearing. • Lower turret bearing and cavity containing moonpool or turret cavity (moonpool refers to the Vessel structure adjacent to the turret and the access space between the turret and vessel. It is Partially filled with seawater). • Mooring spider or mooring buoy (disconnectable) to mooring lines and flexible risers. The interface between the FTS and the process plant on the vessel is known as the FPSO/turret interface. In addition there are internal interfaces within the turret system: • FTS to TTS. • T to TTS. • Turret shaft to mooring buoy or spider. Usually flexible risers connect the swivel to the FPSO/turret interface. Another important interface on an FPSO from a safety standpoint is between the marine and offshore structures. This is usually considered to be at deck level. In this paper the turret system is considered to be part of the offshore structure. 5.8.5 Load Transfer for a Turret System: The turret system will encounter significant loading from the single point mooring from waves and current, and from the weathervaning FPSO vessel. The external interfaces represent the areas of load transfer. For a typical turret system the areas of load transfer are as follows: • Torque arms to swivel


• Main turret bearing • Lower bearing pads • Connections to single point mooring • Bend-stiffeners on flexible risers Where the turret includes a separate mooring spider, or mooring buoy in the case of disconnectable systems, then there will be significant load transfer across this internal interface. The main bearing is the main area of load transfer from turret to the vessel including both axial and radial loads. The lower bearings, usually pads, take much lower loading. The vessel structure adjacent to the turret cavity can encounter significant ovality and loads and is a common area for development of cracking.

6. Power Generation, Distribution, and Electric Load Analysis:

Electrical power in a FPSO is required for various purposes which include deck machinery,

illumination, heating, ventilation, air conditioning, stores, cargo refrigeration, galley, fresh water

and sanitary systems, fire and bilge system, communication systems, radio, radar, electronic

equipments and most important from economic point of view the production modules .The

power production plant must be able to supply sufficient power to all the systems. For this it is

necessary that an accurate estimate of power requirement of FPSO be made at an early stage, so

that power plant order can be placed and unnecessary delays during the construction can be

avoided. This calls for an accurate development of load cases. The highest power consuming

load case gives the Total Plant Peak Load (TPPL). The power plant to be selected must satisfy

this power requirement. Modern practices call for an allowance to meet future expansions which

is unknown at construction stage.

Besides this the FPSO electrical system must be capable of withstanding power failures and be

designed to create a less hazardous environment for workers, like in case of fire, provisions for

power supply to lifeboats, helideck, firefighting equipment and other life saving equipment must

be made. At the same time it should protect the economic interest of the project, i.e. in case of a

local or complete power failure provisions to protect the production modules must be made.

For this the electrical load is classified into three categories- i)Vital Load, ii) Essential Load, iii)Non-essential Load. Vital Loads when loose power may jeopardize safety of personnel or cause serious damage within the plant. Essential loads when loose power cause degradation of the manufactured product. Non-essential loads have no serious effect on safety or production. Some processes in FPSO may handle fluids that are critical to the loss of power e.g. fluids that rapidly solidify and therefore must be kept hot. Other processes such as general cooling water services, air conditioning, sewage pumping may be able to tolerate a loss of supply for several hours without any long-term serious effects. Vital loads are normally fed from a switchboard that has one or more dedicated generators. The generators provide power during the emergency when the main source of power fails. Hence these generators are usually called ‘emergency’ generators and are driven by diesel engines.


They are designed to automatically start, run-up and be closed onto the switchboard whenever a loss of voltage at the busbars of the switchboard is detected. Similarly to take care of essential loads there is a separate generator called ‘essential’ generator. 6.1 Calculation of various load cases For the calculation of necessary electrical load a list of major equipment was necessary. The department library had the list of such equipments for a FPSO of 60,000bbls/d processing capacity. So it was necessary to recalculate the power requirement for an FPSO of 200,000bbls/d processing capacity. The list of the equipment is given in Appendix 6. i)Calculation of power requirement for pumps: The ideal hydraulic power to drive a pump depends on the mass flow rate, the liquid density and the differential height

Fig 6.1: A Centrifugal Pump

- either it is the static lift from one height to an other, or the friction head loss component of the system - can be calculated as

Ph = q g h / 3.6 106

where Ph = power (kW) q = flow capacity (m3/h) = density of fluid (kg/m3) g = gravity (9.81 m/s2) h = differential head (m) Shaft Pump Power The shaft power - the power required transferred from the motor to the shaft of the pump - depends on the efficiency of the pump and can be calculated as

Ps = Ph / (s) where


Ps = shaft power (kW) (s)= pump efficiency Motor Power The motor runs the pump and therefore the power requirement of the motor has to be calculated so that it can give required shaft power. The shaft efficiency data necessary was taken from NEMA (National Electrical Manufacturers Association).

Power Power HP Kw Eff(%)

1 to 4 0.7456 - 2.9827 78.8 5 to 9 3.728 - 6.7104 84

10 to 19 7.456 - 14.1664 85.5 20 to 49 14.972 - 36.5344 88.5 50 to 99 37.28 - 73.8144 90.2

100 to 124 74.56 - 92.4544 91.7 >125 >93.2 92.4

Table6.1:Efficiency data of motor

P= Ps / (m)

where P= motor power(kw) Ps = shaft power (kW) (m) = motor efficiency The calculated motor power is the power to be supplied by local switch board. Ballast Pumps

The ballast pump must have a capacity to fill and drain out all the ballast tanks in one day (taking

into account the crude offloading time). These pumps are also used for deck washing. Total

three pumps are on continuous duty and one is on standby mode, so total there are 4 ballast

pumps. The three pumps working simultaneously give a flow rate of 3228m3/hr at 60m pressure

head. Taking motor efficiency into account this translates to a power requirement of at least

975kw.

Crude Offloading Pumps

The FPSO should have capacity to unload 5 days production, i.e. 5x200,000=1,000,000bbls in

one day. This gives total rate of flow of 6625m3/hr at 200m pressure head. Each tank is

provided with one deep well pump. Also there is one extra portable pump at standby mode in

case any one of the pump fails. The size of pump to be chosen depends upon factors given

below:


Case 1 All 30 pumps working simultaneously. Each pump 221m3/hr(30x221=6630m3/h>min total rate of flow), 200m head.

No heel or trim but large surface effect

Case 2 3 pump working for set of 3 tanks. Each pump 2210m3/h (3x2210 =6630m3/h> min total rate of flow),200m head.

No heel but trim may take place without appropriate ballast.

Case 3 Total 6 pumps working such that three offload from aft and three from forward tanks. Each pump 2210m3/h (6x1105 =6630m3/h> min total rate of flow),200m head.

No heel and trim but high stress may develop in the structure. So an offloading scheme must be decided, which will cause least stress.

Table 6.2: Factors determining size of pump

Whatever be the case the total power consumption remain same. Currently Case3 seems to be

best. The crude offloading system also consists of a tank cleaning pump (300m3/h, 120 m head)

which is used to clean the tanks during regular repair and maintenance or inspection. The

offloading does not take place by pipelines, hence booster pumps are not required and have not

been included in calculation. However in future if the need arises the spare power from the

power plant may be used.

The electrical power consumption for accommodation is 1.5kw per person during normal

operation and 0.75 kw during emergency. The power requirements for the electronic equipments

and other systems have been decided after extensive search on internet and journals.

6.2 Power Estimation for Production Modules

The power requirement of FPSO topside modules was done by calculating requirements of

individual units taken from Appendix 6 and also studying the characteristics process plant.

The FPSO is designed for the following main functions:

• Wellstream processing and oil stabilization and treatment of produced water.

• Gas dehydration and compression, gas-lift for the flowline risers and re-injection of produced gas for reservoir pressure maintenance.

• Seawater sulfate removal and water injection for reservoir pressure maintenance and flooding.

• Storage of stabilized oil, oil metering and offloading of produced oil to export tankers.

• Chemical and methanol injection.


Fig 6.2 The diagram showing entire on field processing

In absence of any expertise or data base the power requirements of equipment such as condenser, reboiler, cooler exchanger, and compressor was extrapolated from the original values. The power for each pump was calculated by estimating the rate of flow and pressure head. In order to estimate the rate of flow and pressure head, it was necessary to study and tabulate the pumping requirements at every stage of processing. The necessary data for the plant of following capacity was searched on internet and central library. The topside of the FPSO has following processing capacity:

• Oil storage: 2,000,000b/d

• Oil Production: 200,000b/d

• Liquids treatment: 300,000b/d

• Produced water treatment: 180,000b/d

• Water Injection: 390,000b/d at 150 bar

• Seawater Sulfate Removal : 400,000b/d

• Gas injection: 8,000,000Sm3/d at 285 bar Oil Treatment The wellhead fluid is treated onboard the FPSO through a single three stage train with gas, oil and water separation at the following pressures (Figure6.2): - 1st stage : 20 to 30 bar.. - 2nd stage : 6 to 6.5 bar. - 3rd stage : 1.5 bar.


Oil heating between first and second stage (Fig.) separators is required to achieve a suitable temperature(65°C) at the desalting stage. After desalting, oil is cooled to 45°C before storage in the tanks. Gas Treatment Flashed-off gas from the separation train is compressed, dried and used as fuel gas and lift gas with the remaining gas re-injected in the reservoir. The gas compression system includes a low pressure (LP)/medium pressure (MP) two-stage centrifugal electric compressor train and two HP three-stage centrifugal compressors. The FPSO is equipped with a 95m high vertical flare. About 1,000,000m3/d of fuel gas is produced which is supplied to the main engine for power production. Sea Water Treatment: The main seawater lifting system comprises electric motor driven submerged lift pumps each sized for 2,300m3/h. The lifted water is divided so that half each flows into the cooling and sulfate removal Treated seawater is pressurized by the three HP water injection pumps (capacity: 860m3/h each), up to 150 bar, and directed to water injection wells. The remaining (70 m3/h) of the treated seawater is used as wash water for the desalters (oil treatment). A careful calculation of rate of flow and pressure head of pumps and knowing the motor efficiency, the power consumed by that pump can be estimated. Other unit where this could not be done , the power requirement was simply extrapolated from the original FPSO data.Once the power requirements of each unit was calculated, the load cases were then tabulated. In all seven load cases have been tabulated. The details are available in Appendix 6. The load case giving maximum power consumption gives TPPL (Total Plant Peak Load). This TPPL is used in selection of power plant. Also load cases give the ‘emergency’ and ‘essential’ loads which have been used to select ‘emergency’ and ‘essential’ generator of the FPSO. 6.3 SELECTION OF TPPL (Total Plant Peak Load): Details shown in Appendix 6.

LOAD CASE CASE DESCRIPTION POWER(Kw) CASE 1 Processing Plant Working 48779.78841

CASE 2 Processing Plant +Ballast and Crude Offloading Control Working 56450.24295

CASE 3 Processing Plant +Ballast and Crude Offloading Control +Accommodation 56660.243

CASE 4 All systems except Ballast and Crude Offloading 49216.36906

CASE 5 All systems working simultaneously(excluding emergency systems) 56886.8236

Max power CASE 6 Emergency Power Requirements 1877.736494

CASE 7 Essential Power Requirements 3196.802245

Table 6.3: Selection of Total Plant peak load

The LOAD CASE 5 the power requirement is highest.The details are available in Appendix B.

So, TPPL=56886.8236


6.4 Selection of Power Plant

After the load has been carefully estimated it is necessary to select the ratings and numbers of generators from a power utility company. A plant may require a combination of generators and incoming feeders. The supply capacity consists of two parts, one part to match the known or initial consumption and a second part to account for keeping a spare generator or feeder ready for service. Any allowance required for future load growth should be included in the power consumption calculations. This two-part approach is referred to as the ‘N ! 1 philosophy’, where N is the number of installed generators or feeders. The philosophy is that under normal operating conditions in a fully load plant N " 1 generators or feeders should be sufficient to supply the load at a reasonably high load factor. Let Pl = power consumption required at the site ambient conditions Pg = rated power of each generator at the site ambient conditions Fo = overload power in % when one generator or feeder is suddenly switched out of service Fi = load factor in % of each generator or feeder before one is switched out of service N = number of installed generators Pl and Pg are the known variables, with Fi and Fo being the unknown variables. Several feasible ratings of Pg may be available and the value of N may be open to choice. A good choice of Pg and N will ensure that the normally running load factor is high i.e. between 66.7% and 90%, whilst the post-disturbance overload on the remaining generators or feeders will not be so high that they trip soon after the disturbance, i.e. less than 125%. The initial load factor can be found as,

Fi = 100*Pl/(Pg(N ! 1))% ; 66.7% < Fi < 90.0%

The post-disturbance overload can be found as,

Fo = 100*Pl/(Pg(N ! 2)) % ; 80 < Fo < 125%

The power plant to be installed in the FPSO must satisfy these restrictions imposed by initial load factor and post-disturbance overload factor. No margin for future expansion of systems is being considered at this stage, as we will see later that power plant capacity under constraints imposed gives a room for extra power, i.e. power that can be produced is slightly more than required power. So, FPSO can handle minor expansions like increase in utilities in accommodation, installation of new electronic system etc. but major expansions that may take place in processing plant cannot be accommodated. 6.5 USE OF HEAT RECOVERY SYSTEM Current interest in reducing emissions and reducing engine operating costs is leading towards the use of more effective waste heat recovery. By using Total Heat Recover Plant, an electrical output of about 10% (this data has been taken from literature made available by WARTSILA) of engine power is possible. Such savings can make a major contribution to improving both plant efficiency and engine emissions.


The details of how this recovery takes place have not been considered. The power plant calculation now includes two cases –(i)Heat recovery system fully functional, so that it supplements the power requirements, and (ii) Heat recovery system not function (in case it breaks down). In both the cases the power plant should have the capacity to to meet the power demands of FPSO and also obey the constraints imposed by load factors. 6.6 POWER PLANT CALCULATIONS The power plant generators were selected from the data available on internet at Wärtsilä website (www.wartsila.com). The prime mover for the generators were decided to be dual fuel engine which can take both MDO/HFO and natural gas (produced from wells) as fuel. Now there are two alternatives available in market-i) turbines-both steam and gas and ii) recently developed reciprocating dual fuel diesel engines. Considering various facts, as discussed below, the steam turbines were rejected and reciprocating dual fuel diesel engines were selected for use as prime movers for the generators. The steam turbines were rejected because of the following reasons (source of information is www.wartsila.com):- i)Engine Room Space: Steam turbines occupy a lot of space inside engine room where as new dual fuel engines are compact. This enables increased cargo capacity for a given displacement, or alternatively smaller FPSO dimensions for a given cargo capacity. ii) Green power: The ratification of the Kyoto Protocol and continuously tightening environmental legislation is driving owners and operators to adopt more environmentally sound solutions. The most critical emissions, CO2 and NOX, are significantly lower in the case of dual-fuel engines compared to turbines. The NOX emissions of the Wärtsilä dual fuel engines are about one-tenth those of the equivalent diesel engines. The combination of the engines’ low fuel consumption and their maximum use of natural gas means the Wärtsilä dual fuel engines also have low CO2 emission levels. iii)Safety: From the safety point of view the dual-fuel engine’s low-pressure fuel gas (5 bar(g)) is preferable to the high-pressure fuel gas (30 bar(g)) required by the gas turbine. ii)Efficiency: The key feature of reciprocating dual fuel diesel engines plants is their superior electrical efficiency compared to similar installations with gasturbines and steam turbine plants. Figure shows the electrical net efficiencies of typical power plants operating at various loads. The efficiency can be improved for both dual-fuel and gas turbine plants with combined cycle plants (i.e. additional waste heat recovery connected to a steam turbine plant).


Fig 6.3 :FPSO prime mover electrical net efficiencies at various loads.

v)Derating, ageing and degradation: The dual-fuel engine offers major advantages over gas turbine installations in terms of derating, ageing and degradation. These features, typically considered a drawback of gas turbines, are almost negligible with the dual-fuel engine. Derating of power plants due to ambient temperatures is described in Figure . Dual-fuel engines start to derate at an ambient temperature of 45 °C, whereas gas turbines are rated at 15 °C and will derate at temperatures above this.

Fig 6.4:FPSO Prime mover derating at various ambient temperatures.


From the list of standard available engines two engine-generator sets were selected to be considered for the power plant. The two engines are 16V50DF and 18V50DF.The engine specifications are given below: Main data Cylinder bore ...............................500 mm Piston stroke.................................580 mm Cylinder output ............................950 kW/cyl Speed ...........................................500, 514 rpm Mean effective pressure ..............20.0, 19.5 bar Piston speed................................. 9.7, 9.9 m/s Fuel specification: Fuel oil .................................... 730 cSt/50 °C 7200 sR1/100 °F ISO 8217, category ISO-F-DMX, DMA and DMB Natural gas……………………MethaneNumber: 80 LHV: min. 28 MJ/nm#, 5.5 bar BSEC 7410 kJ/kWh Engine: 16V50DF & 18V50DF

RATED POWER(50/60Hz) Engine type Engine Kw Generator Kw

16V50DF 15200 14670 18V50DF 17100 16500

Output based on generator efficiency 96.5%

Table 6.4: Rated power of engine

ENGINE DIMENSIONS (mm) and WEIGHTS (tonnes) Engine Type

A B C D F Weight

16V50Df 12 665 4 055 4 530 3 600 1 500 220

18V50Df 13 725 4 280 4 530 3 600 1 500 240

Table 6.5: Engine dimensions


Fig 6.5: The dimensions of engine.

The systems like ballast and crude offloading are not be needed 24 hrs a day. So, in the calculations a separate case has been considered where ballast and crude offloading systems are switched off and we try to find out if we can have a power plant capable of handling other systems efficiently. If we get such a plant we will have a separate generator which will be switched on only when these two systems need to be operated. Also cases with and without heat recovery system have been considered. Power requirements: All systems except Ballast and Crude Offloading = 49216.369Kw (49300Kw app.)

All systems working simultaneously= 56886.823 Kw (57000Kw app)

When Heat Recovery system is working it will give 10% of the engine power as output and this

may be deducted from total consumption.

CASE Heat Recovery System Working Heat Recovery System

Failed All systems except Ballast and

Crude Offloading

44300Kw

49300Kw

All systems working

simultaneously

51200Kw

57000Kw

Table 6.6:


Case1: All systems except Ballast and Crude Offloading a) Heat Recovery System Working

POWER PLANT CALCULATIONS

All Systems Except BW & Crude Offloading Working

Pl Pg N Fi(%) Fo(%)

44300 14670 3 150.9884117 301.9768 Unacceptable

44300 14670 4 100.6589411 150.9884 Unacceptable

44300 14670 5 75.49420586 100.6589 acceptable

44300 14670 6 60.39536469 75.49421 Unacceptable

44300 16590 3 133.5141652 267.0283 Unacceptable

44300 16590 4 89.00944344 133.5142 Unacceptable

44300 16590 5 66.75708258 89.00944 acceptable

44300 16590 6 53.40566606 66.75708 Unacceptable

Table 6.7:

b) Heat Recovery System Not Working POWER PLANT CALCULATIONS

All Systems Except BW & Crude Offloading Working

Pl Pg N Fi(%) Fo(%)

49300 14670 3 168.02999 336.05999 Unacceptable

49300 14670 4 112.02 168.02999 Unacceptable

49300 14670 5 84.014997 112.02 acceptable

49300 14670 6 67.211997 84.014997 acceptable

49300 16590 3 148.58348 297.16697 Unacceptable

49300 16590 4 99.055656 148.58348 Unacceptable

49300 16590 5 74.291742 99.055656 acceptable

49300 16590 6 59.433394 74.291742 Unacceptable

Table 6.8:

Case2: All systems Working Simultaneously(Load Case5)

a) Heat Recovery System Working POWER PLANT CALCULATIONS

All systems Working Simultaneously

Pl Pg N Fi(%) Fo(%)

51200 14670 3 174.5057941 349.0116 Unacceptable

51200 14670 4 116.3371961 174.5058 Unacceptable

51200 14670 5 87.25289707 116.3372 acceptable

51200 14670 6 69.80231766 87.2529 acceptable

51200 16590 3 154.3098252 308.6197 Unacceptable

51200 16590 4 102.8732168 154.3098 Unacceptable

51200 16590 5 77.1549126 102.8732 acceptable

51200 16590 6 61.72393008 77.15491 Unacceptable

Table 6.9:


a) Heat Recovery System Not Working


All systems Working Simultaneously

Pl Pg N Fi(%) Fo(%)

57000 14670 3 194.2740286 388.548057 Unacceptable

57000 14670 4 129.5160191 194.274029 Unacceptable

57000 14670 5 97.13701431 129.516019 Unacceptable

57000 14670 6 77.70961145 97.1370143 acceptable

57000 16590 3 171.7902351 343.58047 Unacceptable

57000 16590 4 114.5268234 171.790235 Unacceptable

57000 16590 5 85.89511754 114.526823 acceptable

57000 16590 6 68.71609403 85.8951175 Unacceptable

Table 6.10:

Here, as stated earlier, Pl = power consumption required at the site ambient conditions Pg = rated power of each generator or feeder at the site ambient conditions Fo = overload power in % when one generator or feeder is suddenly switched out of service Fi = load factor in % of each generator or feeder before one is switched out of service N = number of installed generators or feeders.

In both the cases the configuration which will work satisfactorily with and without heat recovery system is selected.

Case1: All systems except Ballast and Crude Offloading

Two sets of generators satisfy all the constraints. They are:

a) 5 installed generators each of 14670Kw output (if this system is installed separate generator

for BW and crude offloading is needed)

b) 5 installed generators each of 16590Kw output (very low load factor)

Case2: All systems except Ballast and Crude Offloading

Two sets of generators satisfy all the constraints. They are:

a) 6 installed generators each of 14670Kw output (number of generators increased by one)

b) 5 installed generators each of 16590Kw output

Out of the above two 5 installed generators each of 16590Kw output seems to best. This power

production system is selected.


Therefore, the FPSO has a power production system consisting of 5 dual fuel engine-gensets of

Wärtsilä (18V50DF) giving an output of 16590Kw each. Of these 5 generators only 4 work at

time and one is on standby mode.

Now the maximum power output for this power plant must be known. For this once initial load factor ( Fi) is fixed at its maximum value and the power output (Pl) and overload factor (Fo) is calculated. The calculated value of overload factor must be between acceptable limits i.e. ; 80 %< Fo < 125%. If this is condition is true then calculated value of Pl is acceptable. Next, overload factor(Fo) is fixed at it’s maximum value and corresponding power output (Pl) and initial load factor(Fi) is calculated. Again, the calculated value of initial load factor must be between acceptable limits, i.e. 66.7 %< Fi < 90%. If this is true then maximum of the two calculated value of power output is the maximum power output of the plant.


Maximum power load by 5

generator plant

Pg N Fi(fixed) Pl(max) Fo

16590 5 90 59724 120 Acceptable

Pg N Fo(fixed) Pl(max) Fi

16590 5 125 82950 100 Unacceptable

Table 6.11:

From above table it is clear that maximum output of the power plant is 59724Kw. This is greater

than the required power consumption (TPPL=57000 Kw). If heat recovery system works with

this power plant at full efficiency, the power output increases to 65696.4Kw. So, the plant is

capable of meeting any increase in electrical demand due to future expansions.

SELECTION OF ‘ESSENTIAL’ AND ‘EMERGENCY’ GENERATORS

a)Power output of ‘essential’ generator= 3196.802245 Kw= 3200Kw(app.)

Engine selected from Wartsila database is 7L32

Main data Cylinder bore .....................................320 mm Piston stroke.......................................400 mm Cylinder output ................................ 480, 500 kW/cyl Speed ................................................720, 750 rpm Mean effective pressure .................. 24.9 bar Piston speed..................................... 9.6, 10.0 m/s Voltage ........................................... 0.4 – 13.8 kV Generator effi ciency ...................... 0.95 – 0.97 Fuel specification:


Fuel oil…………………………….730 cSt/50°C 7200 sR1/100°F ISO 8217, category ISO-F-RMK 700 SFOC 172 - 180 g/kWh at ISO condition

RATED POWER

Engine type

480 kW/cyl, 720 rpm

500 kW/cyl, 750 rpm

Engine(Kw) Gen.(Kw) Engine(Kw) Gen.(Kw)

7L32 3360 3230 3500 3360

Table 6.12:

ENGINE-GENERATOR DIMENSIONS (mm) and WEIGHTS (tonnes) Engine Type

A E I K L Weight

7L32 9520 2490 1630 2345 4120 65.5

Table 6.13

Fig 6.6: Essential Generator

b)Power output of ‘emergency’ generator= 1877.736494Kw= 1900Kw(app.)

Engine selected from Wartsila database is 6L26

Main data Cylinder bore .....................................260 mm Piston stroke.......................................320 mm Cylinder output ................................ 325, 340 kW/cyl


Engine speed .....................................900, 1000 rpm Mean effective pressure ....................23.0 - 25.5 bar Piston speed...................................... 9.6, 10.7 m/s Generator voltage .............................0.4 - 13.8 kV Generator efficiency ........................0.95 - 0.96 Fuel specification: Fuel oil…………………………….730 cSt/50°C 7200 sR1/100°F ISO 8217, category ISO-F-RMK 700 SFOC 172 - 180 g/kWh at ISO condition

RATED POWER

Engine type

325 kW/cyl, 900 rpm

340 kW/cyl, 1000 rpm

Engine(Kw) Gen.(Kw) Engine(Kw) Gen.(Kw)

6L26 1 950

1 870

2 040

1 960

Table 6.14:

ENGINE-GENERATOR DIMENSIONS (mm) and WEIGHTS (tonnes) Engine Type

A E I K L Weight

6L26 7345 2300 1250 2420 3020 37.7

Table 6.15

Fig 6.7: Emergency Generator


Simple line diagram showing distribution of power in FPSO. No transformers are shown or

distribution voltage, only power distribution has been indicated.

Fig 6.8: Power Distribution


7 Risk Assessment : Risk assessment is an important step towards the risk management process. The basic principle

for the risk assessment is to identify each hazard and its risk level, where risk level can be

obtained from the consequences and frequency of the occurrence of the hazard. There are two

methods of doing risk assessment

• Qualitative risk assessment: Risk assessment in which consequences and frequency are

estimated as a quality or kind (eg. High, low, medium.)

• Quantitative risk Assessment: Risk Assessment in which consequences and frequency are

calculated as numerical value.

Risk assessment in this project is done qualitatively and the basic method we apply in the

assessment is to first find the hazards and their respective consequences and frequencies to

determine risk level and then the preventive action and mitigation. It would be useful to construct

a qualitative risk matrix to find risk level with consequences forming the columns and frequency

forming the rows.

Risk Matrix

Consequences High Marginal Unacceptable Unacceptable Unacceptable

Medium/high Acceptable Marginal Unacceptable Unacceptable

Low/medium Acceptable Acceptable Marginal Unacceptable

Low Acceptable Acceptable Acceptable Marginal

Low Low/medium Medium/high High

Frequency of occurrence

Table 7.1: Risk matrix Frequency of occurrence: Low : The mishap scenario is considered highly unlikely. Low/medium : The mishap scenario is considered unlikely. Medium/high : The mishap scenario might occur. High : The scenario has occurred in the past and/or expected to occur in the future. Consequences: High : Major damage to FPSO and/or serious injury to personal and/or major oil spills High/ medium : damage to FPSO which does not cause major damage or pollution but may cause major damage if not repaired immediately and/or injury to personal. Medium/low : small structural damage and/ or spills or small injury to personal Low : damage that can be repaired without disturbing the process and/ or discomfort to personal. Risk level:


Acceptable : Preventive work can be done without disturbing the process Marginal : Process may be shutdown to do the repair work, preventive measures should be taken immediately to prevent it to escalate. Unacceptable : Process must be shutdown immediately, preventive measures must be done to insure the FPSO and personal safety. Process should be started after all the arrangements are done to insure that the event will not occur again. Hazards in FPSO can be grouped as:

1. Leak of gas and/or oil

a) Blowouts

b) Riser or pipeline leak

c) Process leaks

d) Others.

2. Non process incident

a) Maintenance

b) Fires

c) Tank cleaning

d) Others.

3. Marine Events

a) Shuttle tanker operation.

b) Collision

c) Failures

d) Others.

7.1 Leak of Gas and/ or Oil:

The oil spills is one of the major hazard caused by the FPSO. Oil spill is hazardous to the

environment as well as FPSO, when spills takes place it forms a pool in the sea surface which

may catch fire and approximately 75% of the oil may burn, if FPSO is in close proximity of pool

fire it may cause serious effect and FPSO may collapse too hence FPSO must be moved away

from the pool and also care should be taken such that the flames coming out of fire should not

pass through FPSO.

Hazards Consequences Accident causes Risk level Control/Prevention Blowout Major Release

of oil to sea Earthquake, Dropped object, Material Failure

Unacceptable Blowout can not be controlled, FPSO should be far enough

Riser/pipeline leaks

Subsea wellhead manifolds

Release of oil to sea

Earthquake, material failure, dropped object.

Unacceptable Emergency shutdown, FPSO should be far enough

Production Riser leak

Pipeline and riser contents

Earthquake, dropped object,

Marginal Emergency shutdown


release to the sea

material failure, Extreme vessel motion

Flow-line leak Pipeline and riser contents releases to the sea

Earthquake, dropped object.Material failure, extreme vessel motion

Marginal Emergency shutdown

Process leaks Swivel leak Direct release of

spilled oil to sea, Fire at the swivel, explosion at the swivel

Dropped object, tall structure collapse, helicopter crash

Marginal Emergency shutdown, cover with foam

Leak from Process pipes, flange, valves, pumps

Oil spill over the main deck, limited fire

Loose fittings, corrosion

Marginal Emergency shutdown. Periodic maintenance and checking

Leak from Storage tank

Oil leakage to ballast tank can escalate to damage the hull or bulkhead

Corrosion Marginal Stop the tank loading immediately, empty the tank for maintenance, regular check for maintenance.

Leakage during loading /unloading

Oil spill on the deck or sea, catch fire or explosion

Loose fitting, material defect, handling errors

Marginal Stop the process and check the connections.

Explosion on Turret

Damage the hull Dropped object, helicopter crash

Marginal Emergency shutdown, cover with foam

Table 7.2: Risk assessment of Leak of Oil and Gas

7.2 Non Process incident:

Non operation includes the hazards caused due to the which are not involved in the normal loading and unloading, these hazard generally do not have serious consequences but they will affect the normal FPSO operations. Hazards Consequences Accident cause Risk level Control/prevention

Fire

Electrical Fire Electrical failure, shutdown of related process

High voltage or current, short circuit, from other fire events

Acceptable Fire alarm, cutoff the electrical circuit. Do not use water.

Accommodation fire

Injury to person, localized fire

Human error. Unacceptable Water sprinklers, CO2, fir alarm,


Methanol Fire Limited fire, release of some cargo

Gas weepage from cargo area. Structural support failure

Marginal Emergency shutdown, main deck plate strength, Fire alarm,

Machinery Fire Damage to machinery

Gas weepage from cargo area, poor maintenance

Unacceptable Fire alarm, emergency shutdown

Generator Fire Process fire. Excess vessel motion, Poor maintenance

Marginal Emergency shutdown, use of emergency generator.

Heating System fire

Cargo fire, explosion

Gas weepage from cargo area.

Marginal Emergency shutdown, deluge and foam.

Workshop Fire Injury to personal

Human error

Tank cleaning Tank explosion during high pressure water washing

Oxygen content is greater than accepted limit(8%) in the tank

Marginal Inert gas generator must be run constantly to ensure that the tank atmosphere maintained in the non-explosive range ,fire fighting

Maintenance hazards during

Tank inspection Serious injury to personal

Oxygen content higher than accepted limit

Unacceptable Crude oil washing must be effectively completed, tank atmosphere must be inert to prevent explosion, person must wear, always have rescue equipment on stand-by, Fire Fighting

Deck maintenance

Serious injury to personal

Green water, rough weather condition, FPSO motion

Unacceptable Weather forecast, escape route, communication

Table 7.3 : Risk assessment of Non Process Incident

7.3 Marine Events:

Marine events are mainly related to the operation of shuttle tanker with FPSO and the major

hazard occurs during this operation is collision between FPSO and shuttle tanker, there are some

events which leads to collision with FPSO like supply vessel, support vessel, passing merchant

vessel, Fishing vessel etc., there are also some events related to structural failure like mooring

failure, shuttle tanker operation is consider separately


Hazards Consequences Accident

causes

Risk level Control/Prevention

Collision with

passing merchant

vessel

Major

structural

damage, major

oil spill

Navigation

error in the

merchant

vessel

unacceptable Radio contact with

merchant vessel,

transfer cargo from

damaged tank to

undamaged tank,

shutdown production

Collision with supply

vessel

Minor

structural

damage, less or

no oil spill

Navigation

error in supply

vessel, severe

weather

condition

Marginal DP on supply vessel,

proper

communication

between two vessels.

Collision with

Fishing vessel

Minor

structural

damage

Error in traffic

control

acceptable Coast guard must not

allow fishing vessel

to operate near

FPSO(nearly a range

of 500m from FPSO)

Failure and loss

Mooring failure Failure of two

or more

mooring lines

result in vessel

drifting off

station

Material

failure, severe

weather,

dropped object

Marginal Provide tug

assistance.

Foundering(Structural

failure)

Major damage

to vessel

Severe

weather

condition,

ballasting

errors, poor

cargo

distribution

Marginal Shutdown, Remove

cargo to shuttle

tanker and remove

vessel to dock.

Foundering(capsize) Loss of vessel,

major oil spills

Severe

weather,

ballasting

errors, poor

Marginal Remove cargo shut

down all the process.

Evacuate all the

persons from the


cargo

distribution

vessel.

Crane collapse Structural

damage to

vessel or

module nearby.

Large vessel

motion,

material

defect,

working over

capacity.

Marginal Must working under

crane capacity.

Table 7.4: Risk assessment for Marine event Hazards

7.4 Hazards due to Shuttle Tanker operation:

Here the shuttle tanker used is a DP shuttle tanker and the loading is done in tandem position.

The main hazard occurs due to shuttle operation is collision of shuttle tanker with FPSO whose

frequency of occurrence is more than that of platforms. Consideration is given to hazardous

events that are potentially liable to affect the shuttle tanker in a typical cargo offtake.

Consideration is also given to environmental conditions that a tanker is likely to be subjected to.

The base case risks for each hazardous events and conditions are identified are then subjected to

certain reasonable practicable risk reduction measures. The events and condition are considered

under three separate headings all of which apply inside the 500 meters zone of the FPSO export

facility, viz,

7.4.1 Approaching and berthing

Hazards Consequences Risk level Prevention Main Propulsion Failure

Tanker out of control and may lead to collision with FPSO

Marginal Provide tug assistance, provide tanker with thrusters to provide auxiliary propulsion and ensure that main propulsion and thruster are separated as far as possible so that loss of main propulsion does not result in loss of thruster.

Thruster Failure Reduction in heading transverse momentum control, collision with FPSO

Marginal Provide tug assistance

Steering Gear Failure

Loss in heading control Marginal Provide alternative heading control by main propulsion and thrusters.

Main Power or Electrical Failure

Loss in propulsion and position control, collision

Marginal Provide tug assistance, ensure technical person recover from failure as early as possible.

Position control Loss in position Marginal Provide tug assistance,


system failure control, collision Provide alternative means of controlling position of the tanker.

FPSO dynamic interaction

Not any Acceptable

Adverse weather condition

Loss of control, may lead to collision if close to FPSO

Marginal Provide information about the environment conditions like wave heights, speed and direction of waves.

Fixed obstruction like pipelines, wellheads, installation

Collision with fixed obstruction

Marginal Insure adequate space for maneuvering during approaching, use tug to tow the tanker in case of collision

Other marine activity (fishing boats, supply boats).

Delay, collision with marine vehicle

Acceptable Information about tanker operation should be given to the nearby traffic control

Table 7.5: Hazards due to approaching and berthing of shuttle tanker

7.4.2 Connection of shuttle tanker with FPSO:

There are some hazards due to the dynamic interaction between FPSO and shuttle tanker. When

loading is started FPSO is in loaded condition and have a substantial draft hence surface current

waves force will be dominant force acting on FPSO and shuttle tanker is in ballast condition

hence having less draft and the wind force will be dominant in shuttle tanker, hence force acting

on both the vessel may be in different direction and there will be relative motion between the

vessels.

Hazards Consequences Risk level Prevention Main Propulsion Failure

Loss of control, collision with FPSO, Structural damage, potential loss of oil into sea

Unacceptable Provide tanker with twin main propulsion, twin main engine, twin screw and separated auxiliaries, alarm to warn main propulsion failure, consider hawserless offtake operation to overcome potential problems with recoil action of hawser under tension.

Thruster Failure -same- Marginal Equip tanker with two main propulsion, Ensure that shuttle tanker’s forward section and FSPO export facility is protected against potential collision.

Steering Gear Failure

Potential collision and station keeping difficulties

Unacceptable Provide adequate emergency steering facility with straightforward change over

Main Power or Electrical Failure

Loss of propulsion and position control, collision with FPSO,

Unacceptable Separate power generation from main engine, provide tanker with redundancy in term of power


potential loss of oil into sea

generation and distribution.

Position control system failure

Loss of position control , collision with FPSO

Unacceptable Provide alternative means of controlling position of tanker

FPSO dynamic interaction

Collision, loss of some oil into sea

Unacceptable Adequate separation distance at the shuttle tanker-FPSO interface(typically 80meters), Provide FPSO with DP control system ,thus maintenance of alignment with the tanker during tandem position, Ensure that the personal involved are adequately trained in dealing with problem associated with the dynamic interaction.

Adverse weather condition

Potential collision Unacceptable Provide information about the environment conditions like wave heights, speed and direction of waves.

Fixed obstruction like pipelines, wellheads, installation

Collision Marginal Restricted sectors are well defined and understood and clearly marked on charts, Provide stand by support vessel in ready to tow condition

Other marine activity (fishing boats, supply boats).

Acceptable Information about tanker operation should be given to the nearby traffic control

Table 7.6: Hazards due to connection of shuttle tanker with FPSO

7.4.3 Unberthing and departure

We are not considering the hazards due to unberthing and departure of shuttle tanker because the

FPSO is moored in weathervane and shuttle tanker attached at stern hence if there is any power

loss of propulsion loss, just by disconnecting the shuttle tanker from FPSO wind and current

force will tend to move shuttle tanker away from FPSO. Hence unbething will not cause any

serious hazards.


7.5 Risk evaluation

Hazards Frequency Consequence Risk level

Blowout Low/medium High Unacceptable

Riser/pipeline leaks

Subsea wellheads manifolds Low/medium High Unacceptable

Production Riser leak Low/medium High/medium Marginal

Flowline leak Low/medium High/medium Marginal

Process leak

Swivel leak Medium/high Medium/low Marginal

Leak from Process pipes, flange, valves , pumps

Medium/high Medium/low Marginal

Leak from storage tanks Medium/high Medium/low Marginal

Leakage during loading /unloading Medium/high Medium/low Marginal

Explosion on turret Low/medium High/medium Marginal

Non-Process events

Fire

Electrical Fire Medium/low Medium/low Acceptable

Accommodation fire Medium/high High Unacceptable

Methanol Fire Low/medium Medium/high Marginal

Machinery Fire Medium/high high/medium Unacceptable

Generator Fire Medium/high Low/medium Marginal

Heating System fire Medium/high Low/medium Marginal

Workshop Fire High/medium Low/medium Acceptable

Maintenance hazards

Tank cleaning Low/medium Low/medium Acceptable

Tank inspection Low/medium High Unacceptable

Deck inspection Low/medium High Unacceptable

Marine Events

Collision with passing merchant vessel Low High Unacceptable Collision with supply vessel Low/medium High/medium Marginal

Collision with fishing vessel Low High/medium Acceptable

Failure and loss

Mooring failure low High Marginal

Foundering(structural failure) Low High Marginal

Foundering(capsize) Low High Marginal

Crane collapse Low/medium High/medium Marginal

Table 7.7: Risk evaluation


Risk level for the Shuttle tanker operation is directly calculated from the consequences it causes

because the frequencies of the consequences are nearly same for most of the hazards.

7.6 Escape Route:

Escape route plays an important role in the safety of personal during occurrence of hazards. The

objective of the escape is to ensure a person to reach at safe place at the time of any hazard and

to escape from the FPSO in case of total loss of the FPSO.

Details of the location of escape routes are given in the General Arrangement drawing.

Following considerations are taken for design of the escape route:

1) There are two escape routes on the deck running parallel to the normal route. All the

working areas on the deck must be connected to at least one of the escape routes.

2) Routes are in between the normal access route and the side hull of the FPSO hence to

secure the routes from damage in case of hull damage and in far apart form each other

such that if hazard occur on deck it should not be able to affect both routes

simultaneously.

3) The routes in the deck will be in between topside deck and main deck.

4) These routes will be connected to the escape route in the accommodation.

5) Two routes are chosen because if any route is closed during hazard then one can use the

other one.

6) Escape route is divided into three zones one for accommodation and two in the deck. The

evacuation in topside modules is divided into two zones for the evacuation of the

respective persons working on those zones.

a) Evacuation Route 1: People in accommodation and those are working in the engine

room will escape from this route.

b) Evacuation Route 2.

c) Evacuation route 3

The zones are developed for rescue to take less time hence insure the safety of

personals.

7) Insulation in all the walls of the route to prevent from Green water and Fire.

8) All the working areas must be connected to atleast one of the escape routes.

9) Life Boat is provided for each zone.

8. CONSTRUCTION, INSTALLATION AND FABRICATION:

Construction and Fabrication are the most important processes for the completion of any Marine

Structure project. It will be largely governed by the facilities in shipyard. As our FPSO is of

barge shape, it will be largely consisting of the flat panel. So we can use the process of Mass

Production and Group Technology (Appendix VII 7.1). Installation is the last process before the


working of FPSO. This report gives a brief idea of about shipyard facilities and planning of

FPSO production and installation.

8.1 Activities in FPSO Construction

Main activities in FPSO construction are as follows:

1. Hull form: drawing and lines plan.

2. Hull structure

3. Machinery

4. Outfit

Fig 8.1: Main Activities in FPSO Construction

8.2 FPSO Construction process

Hull structure (steel work) consist most of the part of FPSO construction. The hull structure part

of construction process consists of a component production stages followed by assembly stages

of increasing complexity in which larger assemblies are progressively built up from components

and smaller assemblies culminating in the complete vessel. The manner in which FPSO is

divided into intermediate products at different levels is largely governed by the facilities,

standards and working practices of the shipyard. We are dividing our vessel in following manner

for construction of steel hull structure.

1. Zone: Cargo hold, Engine room, Superstructure

2. Grand Block: 13 grand block.

3. Block: 2 block for each grand block.

4. Assembly.

5. Sub assembly.

6. Component/Raw material

As our vessel consist of lots of similar block and also similar flat plate assembly. This leads that

shipyard must be using group technology for advance shipbuilding.


Fig 8.2: Group Technology for Advanced Shipbuilding

8.3 Block Distribution of FPSO

The block distribution of FPSO will be governed by the facilities, standards and working

practices of the shipyard. It is assumed that the shipyard must have following facilities:

1. Gantry crane: maximum capacity 1200 tonnes.

Detail:

Engine room is divided in two grand blocks.

Remaining hull structure is divided into 11 grand blocks. Each grand block is further

divided into 2 blocks [port (P), starboard(s)].

Dimension and weight of each blocks are:

(Block in cargo hold):


Fig 8.3: Block Construction of FPSO

(Block in cargo hold):

Grand Block

Block Dimension Weight(tonnes) Length(m) Deck

breadth(m) Bottom

breadth(m) 1 1S 24.6 29.76 27.76 1188.6 1P 24.6 26.76 28.76 1181.4

2 2S 24.3 26.76 28.76 1167.7 2P 24.3 29.76 27.76 1174.8

3 3S 24.3 29.76 27.76 1174.8 3P 24.3 26.76 28.76 1167.7

4 4S 24.3 26.76 28.76 1167.7 4P 24.3 29.76 27.76 1174.8

5 5S 24.3 29.76 27.76 1174.8 5P 24.3 26.76 28.76 1167.7

6 6S 24.3 26.76 28.76 1167.7 6P 24.3 29.76 27.76 1174.8

7 7S 24.3 29.76 27.76 1174.8 7P 24.3 26.76 28.76 1167.7

8 8S 24.3 26.76 28.76 1167.7 8P 24.3 29.76 27.76 1174.8

9 9S 24.55 29.76 27.76 1186.3 9P 24.55 26.76 28.76 1179.1


10 10S 24.0 26.76 28.76 1154.0 10P 24.0 29.76 27.76 1161.1

11 11S 20.35 29.76 27.76 993.60 11P 20.35 26.76 28.76 987.65

Table 8.1: Block in cargo hold

(Block in engine room):

Grand Block

Block Dimension Weight(tonnes) Length(m) Breadth(m) Height(m)

E1 E1S1 20.8 28.26 12 901.75 E1P1 20.8 28.26 12 901.75 E1S2 20.8 28.26 12 901.75 E1P2 20.8 28.26 12 901.75

E2 E2S1 20.8 28.26 17.8 825.85 E2P1 20.8 28.26 17.8 825.85 E2P2 20.8 28.26 17.8 825.85 E2S2 20.8 28.26 17.8 825.85

Table 8.2: Block in engine room

8.4 Construction Strategy

Fig 8.4: Construction Strategy


Arrow 1: Arrow gives the manufacturing process. (Bottom to top)

Arrow 2: Arrow gives the planning process. (Top to bottom)

8.5 Block Fabrication

Since all the blocks consist of flat panel assembly. Also most of the blocks are of similar shape

and dimension except engine room blocks. So we are giving the details of fabrication and

construction of one of mid ship block (6S).

Block fabrication steps:

1. Plate preparation

Crane and roller

2. Part Fabrication

The manufacturing process for plates and rolled section can be grouped together based on

the differences in row material, finished part, fabrication process and relevant facilities as

a) Rectangular flat plate

b) Non rectangular flat plate (used in block 11).

c) Internal parts from flat plates.

d) Straight rolled sections.

The different work stages during parts fabrication are:

a) Marking.

b) Cutting.

Following table shows different problem area, associated work stage and facilities during

part fabrication:

PROBLEM AREA WORK STAGE FACILITIES Rectangular flat plates Marking, Cutting, Edge

Preparation Flame planer

Non-rectangular flat plates Marking, Cutting, Edge Flame profiler


Preparation Internal parts from flat plates

Marking, Complex contour cutting, Edge Preparation

Flame profiler

Straight rolled sections Marking, Cutting, Sniping, Scallops

Profile burner, Guillotine

Table 8.3: Problem during part fabrication

3. Part Assembly:

This process is carried away to reduce excessive volume of work at the sub –assembly

level. Part assemblies will be grouped according to their problem areas as:

a) Built-up section: e.g. heavy scantling T-sections (deck girder).

b) Sub-block part: e.g. bracket plate stiffened with a face plate or flat bar.

4. Sub block assembly:

Block is divided into following sub-blocks

a) Double bottom sub-block

b) Double hull side shell sub block (side shell, inner side shell and side shell

girders).

c) Stiffened longitudinal bulkhead.

d) Stiffened transverse bulkhead.

e) Stiffened deck plate

Fig 8.5: Sub Block Assembly


This level of manufacturing consists of assembled structural parts like longitudinals,

transverse, girders, web frames, floors, etc.

In our FPSO case this level can be done on mass production theory. As stiffened panels,

consisting of plates attached to stiffeners, constitute almost part of sub assembly. So these

sub-assemblies can be mass produced size by size in process with appropriate welding,

equipment and facilities for material handling and transfer.

For this we will go through Panel line (flat panel assembly) process. See appendix VII,

7.2.

Fig 8.6: Flat panel

5. Block Assembly:

Figure below is showing how the sub-block will be joined to complete a block. Numbers

given in figure are indicating the order in which sub-blocks are welded to form a block.

Step1: Laying of Double bottom.

Step2: Welding of Side shell Sub-block with Double Bottom.

Step3: Welding of Longitudinal bulkhead with Double Bottom.

Step4: Welding of Transverse bulkheads with Double Bottom, Longitudinal

bulkhead and side shell.


Step 5: Welding of Deck plate with side shell, transverse and longitudinal

bulkhead.

Fig 8.7: Block Assembly

8.6 Engine room Construction:

Engine construction will de done in following steps:

1. Block E1P, E1S will be constructed first. The process of fabrication of block is same as

described for the 6S block.

2. E1 grand block will be constructed at dry dock with both of the blocks.

3. Then 5 duel fuel engines will be installed in double bottom of E1 block.

4. Block E2S and E2P will be welded with Grand Block E1, Grand Block will only have

Level 2 Deck initially.

2


5. Now machines and auxiliary machines will be installed at level 2 Deck

6. Level 3 deck will be welded.

7. In similar manner auxiliary machines and generator and other decks will be installed or

welded.

8. Finally main deck will be welded after installation of all the machines.

Fig 8.8: Engine Room Construction

8.7 Welding Detail:

Following table shows the welding process we are using during fabrication and construction,

with detail of application of each welding.

SI No.

PROCESS APPLICATION

1 Shielded Metal Arc-Manual All position welding 2 Gravity Welding For down-hand welding of stiffeners with plates.

Stiffeners are welded during panel fabrication.

3 Submerged Arc Welding For two side butt welding of plate with another plate, also for joining two panels.

4 Flux Cored Arc Welding Welding of the deck plate during block erection. 5 Gas Shielded Welding Short welds protected from wind 6 Electroslag Welding Long vertical butt welding of side shell plating and

longitudinal bulkhead. Welding between transverse and


bulkheads with deck plating. Longitudinal junction with transverse or bulkheads.

7 Electro gas welding Vertical fillet welding of transverse bulkheads to longitudinal bulkheads and side shell plating.

Table 8.4: Welding processes

8.8 Outfitting:

Outfitting will be done in such a manner such that the process can carried out in assembly hall so

that we can get better working condition and better access.

Outfitting will be carried out in following steps 1) On -flat panel assembly. 2) On -block. 3) On –board. On –board outfitting work is carried out at the hull erection stage or at the

post launch stage.

Outfitting work like fittings of pipes, brackets, lifting pads etc can be performed at all stage. Outfitting work like installation of modules, accommodation, mooring and anchoring equipment can be done at on-board stage. 8.9 Topside Modules Installation Selection of modules will depend upon the owner of the FPSO. Whether owner wants to order a new module meeting the requirement of the FPSO or just purchased a old module which was used previously in other installation. Modules can be of two types

1) Custom made modules: Newly constructed Topsides ordered specifically for this FPSO. Frame spacing of the module casing must match the frame spacing of the FPSO hence during installation of there modules each frame of the FPSO comes under the module will be directly connected with the frames of module.

2) Purchased modules: Modules that have been used in other offshore installations and have been recovered from them when decommissioned. These modules can have different frame spacing than FPSO, hence during installation of these modules we have to match the frame spacing by proving some extra structural member. Figure shown below is an example of how to match the frame spacing of the two structures.

Fig 8.9:Matching the Frame Spacing of Two Structures


Dark plates are from FPSO with transverse T-Beam supporting the module of less spacing. The supporting bar extending from the T-Beam is supporting the module such that the spacing at the end of the supporting bar will be equal to the frame spacing of the module hence these supporting bar will be connected with the module frame spacing. Hence all the load of the module will be transmitting through module frames to supporting bar to the FPSO frame.

8.10 Installation of FPSO There is no propulsion system in our FPSO, since it is not required during the service life. FPSO is therefore towed to site using tugs. The towing operator and towing vessels should be carefully selected to ensure that they will be able to reliably tow the FPSO at the desired speed within the schedule and during an acceptable weather window.

For executing the installation work of FPSO the operator has three discrete tasks to manage:

a) Installation of mooring anchor legs b) Hook-up of the FPSO with its anchor legs c) Installation of riser an subsea system

Installation of mooring anchor legs is done prior to the FPSO arrival The type of vessel ( tug or supporting vessel) used for installation will depend largely on location, the environmental condition, water depth, mooring and riser system design. Mooring system on FPSO are specific for each installation so the vessels recovering handling and transferring the mooring system will almost certainly be required to be specially adopted for that specific task.

After installation of mooring anchor leg system hook-up with the FPSO will be done. A sufficient number of vessels should be available to ensure that the FPSO should be maintained in the desired position and heading under all likely environmental condition. While the tugs hold the FPSO in position other tugs pick-up the ends of the preinstalled mooring anchor lines and bring them toward the FPSO fairleads where they are connected to winches that are installed on the FPSO. The tugs are released when a sufficient number of anchor lines are connected. The mooring line hook-up operation continues until all the anchor legs are connected and tensioned. Finally riser and subsea system will install.

9. DECOMMISSIONING AND DISMANTLING:

Decommissioning is the process where the operator of an offshore oil or gas installation and

pipeline goes through in order to plan, gain approval for and implement the removal, disposal

and re-use of an offshore installation when it is no longer needed for its current purpose. The

decommissioning and re-use are very important, both with respect to environmental and

economical conditions. While decommissioning of the system, care must be taken so that the site

will be restored to a condition that minimizes residual environmental impacts, permits

reinstatement of fishing in that area and unimpeded navigation through it. The vessels are

designed with the prospect that it would be modified later to be used in other fields. Though the

process facilities of these vessels are generally custom made for a specific application, other


major components including pressure vessels, piping, and equipment that can be used on similar

fields in future applications. If initially designed with an eye towards an extended life, and the

potential for expansion, the equipment could more easily be converted and moved to another

field with similar fluid characteristics. FPSOs lend themselves readily to such conversions and

movements because of their ship shape.

9.1 Requirements for Recycling

Before reuse and recycling, engineering documents of the equipment should be checked for

compatibility with the new production fluid composition and design conditions: manifolds,

pressure vessels, valves, piping, pumps, heat exchangers, water treatment facility, flare system,

gas compression system, and E&I system. This is followed by a thorough inspection survey of

existing equipment and infrastructure. Once the existing and new requirements are investigated

for suitability, an appropriate modification plan will be made.

The following requirements are key factors to judge re-usability of an FPSO vessel for a new field:

• Operation duration requirement at the new field • Crude storage capacity requirements • Double hull requirement.

If the FPSO is judged to be reusable for the next assignment, the following factors will be

studied and the conversion plan will be developed accordingly:

• Life extension and repair • Conversion of offloading system • Conversion of tank heating • Conversion of safety facility • Regulations • Site environment.

9.1.1 Risers:

Risers are typically, custom designed for a specific site. The design of the structure and the

configuration is a complicated function of fluid service, site, water depth, environment, and

flowing vessel response characteristics. However, careful design in the choice of riser

configuration, size and interface between vessel and the wellheads can allow the re-utilization of

the FPSO without major modifications at the riser interface. In the initial design, it is important

to properly design the structure and configuration to enhance the potential for re-use.

Configurations like the lazy wave and free hanging catenary risers are more readily adaptable to

re-utilization as the riser forms part of the flow line after touchdown; thus the length of the riser

is not too dependent on water depth.

The following are key parameters for judging the reusability of the riser system:

• Service life: Is the residual life adequate for the new field life? • Type of service


• Design temperatures and pressures • Site particulars: water depth and ocean environment? • Riser configuration: Does the riser configuration allow for use at another site? • Installation equipment

A thorough inspection plan must be carried out on the recovered riser. This includes the end

fittings, external sheath wear, external buoyancy modules, and possible NDE inspection of the

inner carcass. Re-certification of the riser by the riser manufacturer or the certifying authority

may also be required. A detailed inspection plan with specific reject/accept criteria must be

developed with the riser manufacturer and/or classification society for the new field. A detailed

examination of the external sheath and the end fittings will be required. Buoyancy modules will

need to be removed, refurbished, and replaced during re-installation.

9.1.2 Turret Re-utilization:

FPSO tanker turret facilities can vary tremendously in type, size, and function. Given that the

most basic capabilities of a turret are governed by load capacity and riser space availability,

turrets may be categorized accordingly:

• Load capacity: Turret load capacity may be categorized as either low load capacity or high load capacity for simplicity. Low load capacity may be considered when the total maximum resultant load due to off-vessel moorings plus risers is less than approximately 1,200 tons.

• Riser capacity: Turret categories based on riser capacity are: few risers, less than 10; moderate number of risers, between 10 and 25; and many risers, greater than 25.

The turret system piping, manifold, swivels, and safety features must be evaluated for

compatibility with the new field requirements following a thorough inspection to determine the

existing condition. Evaluation of the swivels, piping, manifold, and other components must

consider materials, corrosivity, pressure, size, and pigging requirements.

Other factors involved in the process of decommissioning and re-use include the following: • Decommissioning: Prior to disconnection of the mooring and riser systems, the

machinery related to anchor leg or riser installation/de-installation is reconditioned. • Refurbishment, conversion: Turret system refurbishment is best carried out at a

shipyard. Dry-docking may be required depending on the modification plan. • FPSO mooring: Anchor leg patterns and component sizes, grades and lengths are

generally specific to a certain site.

With proper consideration of corrosion, wear, fatigue and handling, modern anchor chain and

wire components may be considered for reuse. Inspection programs to re-certify anchor chain

exist and should be adopted or modified to meet the new field's functional requirements. Careful

planning for the recovery of the anchor legs must allow for handling operations, which will not

damage the components.


9.1.3 Subsea systems:

Subsea systems are a packaged system; they incorporate intricate machined hardware sized for

the flow rates, well shut-in pressures, installation vessel interfaces, and intra-field connections.

Suitability of subsea hardware for decommissioning and re-use is primarily a function of valve

size, material class, and its remaining useful design life. Subsea hardware decommissioning is

accomplished during well abandonment. After the well is controlled and killed, cement is usually

circulated into the well through prepared perforations in the tubing string. Once the well is dead,

the flowlines and associated subsea hardware, such as subsea manifolds, flowline connection

hardware, and other components are circulated with water. The flowline and control umbilical

connections are disconnected and the subsea tree is recovered. Subsea wellheads are then cut

approximately 3 meters below the seafloor and pulled up as a single salvaged unit; wellhead,

guide bases, casing hangers, pack-offs, and casing joint stubs. All remaining subsea hardware is

either removed from the seafloor, or abandoned in place, depending on local regulation

requirements, water depth, and proximity to shipping lanes or anchorages, and abandonment

costs.

9.2 Dismantling (Ship Breaking) Consideration of dismantling is considered due to rising awareness about the plight of workers in ship breaking yards of India, Pakistan and Bangladesh where cheap unskilled labor is easily sourced and exploited for the ship breaking activity. The attempt is to identify problems and suggest changes so that working environment can be made less hazardous. Banning of ship breaking in these countries would deny the meager income these workers have from this industry and is therefore unacceptable. Some of steps that a owner of FPSO being dismantled can take are:

• Before beaching of FPSO, the topsides must be cleaned and ensured that they do not carry hazardous materials. Tanks of FPSO must be cleaned.

• The owner should supply a detailed process of dismantling, so that collapse of structure during dismantling is avoided.

• The owner should also supply a detailed document to breaking yard, indicating zones where there is possibility of toxic fumes and gases.

• There are few countries which build offshore structures or ships and even less that decommission them. Each group of countries could be specifically targeted, for example, to require those ordering ships to write recyclable material into their specifications and to document any hazardous material used.

• While the ultimate goal would be a Code of Practice on Safety and Health in Ship Scrapping, a number of interim steps such as training videos, hand-outs (translated into the local languages), seminars and workshops could be organized, with the goal of improving worker safety.


Fig.9.1: Major ship breaking Tasks (taken from www.osha.gov)

9.3 Conclusion:

The timing of future decommissioning activities is not fixed. It depends on the length of the

lease, the rate of reservoir depletion, the market value of oil or gas, and whether the unit might

serve an extended use. The abandonment of an offshore installation is governed by the global or

regional regulations. At the end of production life of the USAN field, the FPSO will

decommission and abandon the site according to the regulations and laws at that time. Sub-sea

infrastructure will be removed; wells will be plugged and abandoned; buried flowlines will be

abandoned after flushing. The ultimate disposition of the FPSO will depend upon its condition at

the end of the production life at the USAN field. All anchor, lines, and chains will be recovered.

The topsides equipments will be decommissioned at yard if the FPSO is not fit for re-use.


References:

Practical Ship Design, Watson

Practical Design of Ships and Other Floating Structures, You Sheng Wu, Wei Cheng Cui and

Guo-Jun Zhou

Ship Design Methods, Thomas Lamb

The Ship Design And Construction, Taggart

Principles of Naval rchitecture, Vol I,II,III, Edward V. Lewis

Hand Book of Ocean Engineering, Subrata Chakrabarti

Guidelines for Risk Based Process Safety, Centre for Chemical Process Safety

International convention for Safety of Life at Sea,1974

MARPOL Regulations

International Load Line Convention,1966 including protocol of 1988 relating to the Load Lines

Convention, 1966

Offshore Hydromechanics, J.M.J Journee and W.W. Massie

ABS Crew Habitability on Offshore Installations

ABS Rules for Building and Classifying Steel Vessels

www.osha.gov

www.aluminium-offshore.com

www.wartsila.com


APPENDIX


APPENDIX I

1) GENERAL ARRANGEMENT & HULL DESIGN

Name L B D T Storage Slop tank Fuel Oil

m m m m m3 m3 m3

Aoka Mizu 248.12 42 21.2 14.9 105132 7150 2982

Bloe Holm 242.3 42 21.2 119502 7602 2900

Gas Dowr 242.3 42 21.1 113800 6650 2650

Hæwene Brim 252 42 23.2 101065 3315 3000

Munin 252 42 23.2 101236 3315 3158

Uisge Gorm 248.3 39.9 20.5 101350 4450 2400

Hanne Knutsen 264.68 42.5 22 15 144799 4860 3743

Griffin Venture 243 42 23 15 105556

Bohai ming zu 210 33 18 12 62005

Bohai You Yi Hao 217 31 18 10 62005

Cang Qing Hao 217 31 18 11 58504

Schiehallion 246 45 27 20 151038

Girassaol 300 60 31 23 317974

Balder 211 36 21 14

Jotun A 223.5 41.5 23.75 98071 2882 2278

Crystal Sea 101 21 12 9 7450 500 350

Challis Venture 238.5 39 21.4 14 139000

Gryphon A 259 41 24 16 82469

Mitsui F601 FPSO 219 38 23 17

Navion Munin 252 42 23 16

Berge Hugin 252 42 23 16 101400

San Jacinto 105 21 9 6 8427

Terra Nova 292 46 28 19

Petrojarl I 209 32 18 13

Petrojarl Varg 214 38 21 16 15263

Ramform Banff 120.4 53.4 16 12 19079

Anoa Natuna 194 39 21 14 87443

Seillean 250 37 21 12 28618

Anasuria 226 45 24 17

Asgard A 278 45 27 19

Nome 260 41 25 19

Captain FPSO 214 38 24 18

Northen Endeavour 273 50 28 19

Offshore oil III 262 46 24 158987

Qinhuangdao 287 51 158987

Henrique Dias 330 54.5 27.8 317974


Jose Bonifacio 320 54.5 28 317974

Kizomba A 285 63 32.2 349771.4

Kizomba B 285 63 32.2 349771.4

Greater Plutonio 310 58 32 317974

Akpo FPSO 310 61 31 317974

Jabiru Venture 285 41 22 17

Challis Venture 238.5 39 21.4 14.35 139000

Anoa Natuna 166 39 21.4 14.45 87600

Table 1.1: Ship Data Used


Table 1.2 : Tank and Compartment Definitions

APPENDIX II

2) WEIGHT, BUOYANCY AND STABILITY

2.1) Damage Stability

CASE T Displacement Vw Area z l A

m tonne knot m2 m m

Dcase 1 22.648 381703 100 5787.6454 34.36457024 23.04057 0.059391

Dcase 2 22.112 372521 100 5951.2326 34.03513894 22.97914 0.062408

Dcase 3 22.003 365308 100 5984.4994 33.96855731 22.96706 0.063962

Dcase 4 21.997 365185 100 5986.3306 33.96489616 22.9664 0.064001

Dcase 5 21.991 365275 100 5988.1618 33.96123542 22.96574 0.064003

Dcase 6 21.987 365271 100 5989.3826 33.95879515 22.9653 0.064016

Dcase 7 21.984 365267 100 5990.2982 33.95696507 22.96497 0.064025

Dcase 8 21.982 365264 100 5990.9086 33.95574507 22.96475 0.064032

Dcase 9 21.982 365263 100 5990.9086 33.95574507 22.96475 0.064032

Dcase 10 21.982 365262 100 5990.9086 33.95574507 22.96475 0.064032

Dcase 11 21.766 362441 100 6056.8318 33.82424607 22.94125 0.065174

Dcase 12 23.482 367946 100 5533.1086 34.88437866 23.14338 0.059164

Dcase 13 22.307 368109 100 5891.7186 34.15459323 23.00109 0.062584 Table 2.1: Calculation of parameter A for the equation Heeling arm = A cos^n(phi)

a) Dcase1

Tanks Damaged: Slop ballast bottom 1.1, Slop ballast starboard, Slop tank1, Ballast tank

forward most.


Fig 2.1

RESULT

Static Stability: Righting arm at the first angle of static equilibrium (st1) should not be larger

than 0.6 of the maximum righting arm.

(GZ st1) / GZmax = .0135/3.424 =.0039 < 0.6 (PASS)

Ratio of areas type 2 - general wind heeling arm unit Pass Heeling arm = A cos^n(phi) A = 0.0594 m n = 2 gust ratio 1 Area1 integrated from the greater of spec. heel angle 0 deg

angle of equilibrium (with heel arm) 2.6 deg 2.6 GZ st1=0.0135

to the lesser of spec. heel angle 70 deg angle of first GZ peak 58.5 deg angle of max. GZ 58.5 deg 58.5 GZmax=3.424 angle of max. GZ above heel arm 58.5 deg first downflooding angle n/a deg angle of vanishing stability (with heel arm) 104 deg Area2 integrated to the lesser of roll back angle from equilibrium (with heel arm) 25.0 (-22.4) deg -22.4 Area1 / Area2 shall be greater than (>) 140 % 404.251 Pass Intermediate values Equilibrium angle with heel arm deg 2.6 Area1 (under GZ), from 2.6 to 58.5 deg. m.deg 104.847 Area1 (under HA), from 2.6 to 58.5 deg. m.deg 2.365 Area1, from 2.6 to 58.5 deg. m.deg 102.483 Area2 (under GZ), from -22.4 to 2.6 deg. m.deg -23.918 Area2 (under HA), from -22.4 to 2.6 deg. m.deg 1.433 Area2, from -22.4 to 2.6 deg. m.deg 25.351

Table 2.2: Dynamical Stability


Draft Amidsh. m 22.648 Displacement tonne 381703 Heel to Starboard degrees 1.6 Draft at FP m 25.02 Draft at AP m 20.276 Draft at LCF m 22.548 Trim (+ve by stern) m -4.744 WL Length m 305.237 WL Beam m 56.542 Wetted Area m^2 32911.885 Waterpl. Area m^2 16525.742 Prismatic Coeff. 0.868 Block Coeff. 0.841 Midship Area Coeff. 0.969 Waterpl. Area Coeff. 0.958 LCB from Amidsh. (+ve fwd) m -1.547 LCF from Amidsh. (+ve fwd) m -6.422 KB m 11.315 KG fluid m 18.333 BMt m 11.753 BML m 316.732 GMt corrected m 4.73 GML corrected m 309.709 KMt m 23.068 KML m 328.047 Immersion (TPc) tonne/cm 169.422 MTc tonne.m 3873.419 RM at 1deg = GMt.Disp.sin(1) tonne.m 31508.02 Max deck inclination deg 1.8 Trim angle (+ve by stern) deg -0.9

Table 2.3: Equilibrium Result


Graph 2.1

b) Dcase2

Tanks Damaged: Slop ballast bottom 1.1 ,Slop ballast starboard, Slop tank1, Cargo10.1, Ballast

starboard10, Ballast bottom10.1.

Fig 2.2

RESULT



(GZ st1) / GZmax = 0.0560/3.275 =.0171 < 0.6 (PASS)

Ratio of areas type 2 - general wind heeling arm Pass

-2

-1

0

1

2

3

4

-25 0 25 50 75 100

Max GZ = 3.424 m at 58.5 deg.

Ratio of areas type 2 - general wind heeling arm

Heel to Starboard deg.

GZ

m


Heeling arm = A cos^n(phi) A = 0.0624 m n = 2 gust ratio 1 Area1 integrated from the greater of spec. heel angle 0 deg angle of equilibrium (with heel arm) 3.8 deg 3.8 GZ st1=0.0560 to the lesser of spec. heel angle 70 deg angle of first GZ peak 58 deg angle of max. GZ 58 deg 58 GZmax=3.275 angle of max. GZ above heel arm 58 deg first downflooding angle n/a deg angle of vanishing stability (with heel arm) 102.5 deg Area2 integrated to the lesser of roll back angle from equilibrium (with heel arm)

25.0 (-21.2) deg -21.2

Area1 / Area2 shall be greater than (>) 140 % 396.405 Pass Intermediate values Equilibrium angle with heel arm deg 3.8 Area1 (under GZ), from 3.8 to 58.0 deg. m.deg 95.557 Area1 (under HA), from 3.8 to 58.0 deg. m.deg 2.286 Area1, from 3.8 to 58.0 deg. m.deg 93.271 Area2 (under GZ), from -21.2 to 3.8 deg. m.deg -22.086 Area2 (under HA), from -21.2 to 3.8 deg. m.deg 1.443 Area2, from -21.2 to 3.8 deg. m.deg 23.529


Draft Amidsh. m 22.112 Displacement tonne 372521 Heel to Starboard degrees 2.7 Draft at FP m 22.89 Draft at AP m 21.335 Draft at LCF m 22.082 Trim (+ve by stern) m -1.555 WL Length m 305.204 WL Beam m 56.582 Wetted Area m^2 32576.173 Waterpl. Area m^2 16499.603 Prismatic Coeff. 0.922 Block Coeff. 0.872 Midship Area Coeff. 0.945 Waterpl. Area Coeff. 0.955


LCB from Amidsh. (+ve fwd) m -4.534 LCF from Amidsh. (+ve fwd) m -6.016 KB m 11.061 KG fluid m 18.553 BMt m 11.789 BML m 331.697 GMt corrected m 4.269 GML corrected m 324.176 KMt m 22.849 KML m 342.757 Immersion (TPc) tonne/cm 169.154 MTc tonne.m 3956.831 RM at 1deg = GMt.Disp.sin(1) tonne.m 27751.561 Max deck inclination deg 2.7 Trim angle (+ve by stern) deg -0.3

Table 2.5: Equilibrium analysis

Graph 2.2

c) Dcase3

-2

-1

0

1

2

3

4

-25 0 25 50 75 100

Max GZ = 3.275 m at 58 deg.



GZ

m


Tanks Damaged: Cargo10.1, Ballast starboard10, Ballast bottom10.1, Cargo9.1, Ballast

starboard 9, Ballast bottom 9.1.

Fig 2.3

RESULT



(GZ st1) / GZmax = 0.058694/3.377 =.0174 < 0.6 (PASS) Ratio of areas type 2 - general wind heeling arm Pass Heeling arm = A cos^n(phi) A = 0.0639 m n = 2 gust ratio 1 Area1 integrated from the greater of spec. heel angle 0 deg angle of equilibrium (with heel arm) 3 deg 3 to the lesser of spec. heel angle 70 deg angle of first GZ peak 58 deg angle of max. GZ 58 deg 58 angle of max. GZ above heel arm 58.5 deg first downflooding angle n/a deg angle of vanishing stability (with heel arm) 103.3 deg Area2 integrated to the lesser of roll back angle from equilibrium (with heel arm)

25.0 (-22.0) deg -22

Area1 / Area2 shall be greater than (>) 140 % 419.34 Pass Intermediate values Equilibrium angle with heel arm deg 3 Area1 (under GZ), from 3.0 to 58.0 deg. m.deg 98.421 Area1 (under HA), from 3.0 to 58.0 deg. m.deg 2.334 Area1, from 3.0 to 58.0 deg. m.deg 96.087 Area2 (under GZ), from -22.0 to 3.0 deg. m.deg -21.477 Area2 (under HA), from -22.0 to 3.0 deg. m.deg 1.437 Area2, from -22.0 to 3.0 deg. m.deg 22.914



Draft Amidsh. m 22.003 Displacement tonne 365308 Heel to Starboard degrees 1.9 Draft at FP m 22.431 Draft at AP m 21.575 Draft at LCF m 21.983 Trim (+ve by stern) m -0.856 WL Length m 305.201 WL Beam m 56.553 Wetted Area m^2 32508.137 Waterpl. Area m^2 16244.199 Prismatic Coeff. 0.922 Block Coeff. 0.884 Midship Area Coeff. 0.959 Waterpl. Area Coeff. 0.941 LCB from Amidsh. (+ve fwd) m -6.256 LCF from Amidsh. (+ve fwd) m -7.018 KB m 11.009 KG fluid m 18.554 BMt m 11.721 BML m 336.83 GMt corrected m 4.145 GML corrected m 329.253 KMt m 22.731 KML m 347.839 Immersion (TPc) tonne/cm 166.536 MTc tonne.m 3940.986 RM at 1deg = GMt.Disp.sin(1) tonne.m 26424.595 Max deck inclination deg 2 Trim angle (+ve by stern) deg -0.2



Graph 2.3

d) Dcase4

Tanks Damaged: Cargo 9.1, Ballast starboard 9, Ballast bottom 9.1, Cargo 8.1, Ballast starboard

8, Ballast bottom 8.1.

Fig 2.4

RESULT



(GZ st1) / GZmax = 0.056143/3.377 =.0166 < 0.6 (PASS)

Ratio of areas type 2 - general wind heeling arm Pass

-2

-1

0

1

2

3

4

-25 0 25 50 75 100




GZ

m


Heeling arm = A cos^n(phi) A = 0.064 m n = 2 gust ratio 1 Area1 integrated from the greater of spec. heel angle 0 deg angle of equilibrium (with heel arm) 2.9 deg 2.9 to the lesser of spec. heel angle 70 deg angle of first GZ peak 58 deg angle of max. GZ 58 deg 58 angle of max. GZ above heel arm 58.5 deg first downflooding angle n/a deg angle of vanishing stability (with heel arm) 103.3 deg Area2 integrated to the lesser of roll back angle from equilibrium (with heel arm)

25.0 (-22.1) deg -22.1



Draft Amidsh. m 21.997 Displacement tonne 365185 Heel to Starboard degrees 2 Draft at FP m 22.349 Draft at AP m 21.645 Draft at LCF m 21.984 Trim (+ve by stern) m -0.705 WL Length m 305.201 WL Beam m 56.553 Wetted Area m^2 32505.839 Waterpl. Area m^2 16238.752 Prismatic Coeff. 0.925 Block Coeff. 0.887 Midship Area Coeff. 0.959


Waterpl. Area Coeff. 0.941 LCB from Amidsh. (+ve fwd) m -5.048 LCF from Amidsh. (+ve fwd) m -5.711 KB m 11.01 KG fluid m 18.555 BMt m 11.719 BML m 349.227 GMt corrected m 4.142 GML corrected m 341.65 KMt m 22.729 KML m 360.237 Immersion (TPc) tonne/cm 166.48 MTc tonne.m 4087.988 RM at 1deg = GMt.Disp.sin(1) tonne.m 26399.6 Max deck inclination deg 2 Trim angle (+ve by stern) deg -0.1


Graph 2.4

e) Dcase 5



-2

-1

0

1

2

3

4

-25 0 25 50 75 100




GZ

m


Fig 2.5

RESULT



(GZ st1) / GZmax = 0.054469/3.375 =.0161 < 0.6 (PASS)

Dynamical Stability Ratio of areas type 2 - general wind heeling arm Pass Heeling arm = A cos^n(phi) A = 0.064 m n = 2 gust ratio 1 Area1 integrated from the greater of spec. heel angle 0 deg angle of equilibrium (with heel arm) 2.8 deg 2.8 to the lesser of spec. heel angle 70 deg angle of first GZ peak 58 deg angle of max. GZ 58 deg 58 angle of max. GZ above heel arm 58.5 deg first downflooding angle n/a deg angle of vanishing stability (with heel arm) 103.3 deg Area2 integrated to the lesser of roll back angle from equilibrium (with heel arm)

25.0 (-22.2) deg -22.2

Area1 / Area2 shall be greater than (>) 140 % 415.329 Pass Intermediate values Equilibrium angle with heel arm deg 2.8 Area1 (under GZ), from 2.8 to 58.0 deg. m.deg 98.975 Area1 (under HA), from 2.8 to 58.0 deg. m.deg 2.342 Area1, from 2.8 to 58.0 deg. m.deg 96.632 Area2 (under GZ), from -22.2 to 2.8 deg. m.deg -21.831


Area2 (under HA), from -22.2 to 2.8 deg. m.deg 1.435 Area2, from -22.2 to 2.8 deg. m.deg 23.266



Table 2.10: Equilibrium Analysis


Graph 2.5

f) Dcase 6



Fig 2.6

RESULT



(GZ st1) / GZmax = 0.05802/3.372 =.0172 < 0.6 (PASS)

-2

-1

0

1

2

3

4

-25 0 25 50 75 100




GZ

m


Ratio of areas type 2 - general wind heeling arm Pass Heeling arm = A cos^n(phi) A = 0.064 m n = 2 gust ratio 1 Area1 integrated from the greater of spec. heel angle 0 deg angle of equilibrium (with heel arm) 2.8 deg 2.8 to the lesser of spec. heel angle 70 deg angle of first GZ peak 58 deg angle of max. GZ 58 deg 58 angle of max. GZ above heel arm 58.5 deg first downflooding angle n/a deg angle of vanishing stability (with heel arm) 103.3 deg Area2 integrated to the lesser of roll back angle from equilibrium (with heel arm)

25.0 (-22.2) deg -22.2



Draft Amidsh. m 21.987 Displacement tonne 365271 Heel to Starboard degrees 1.9 Draft at FP m 22.202 Draft at AP m 21.771 Draft at LCF m 21.982 Trim (+ve by stern) m -0.431 WL Length m 305.2 WL Beam m 56.553 Wetted Area m^2 32501.82 Waterpl. Area m^2 16243.242 Prismatic Coeff. 0.931 Block Coeff. 0.892


Midship Area Coeff. 0.959 Waterpl. Area Coeff. 0.941 LCB from Amidsh. (+ve fwd) m -2.528 LCF from Amidsh. (+ve fwd) m -2.984 KB m 11.008 KG fluid m 18.554 BMt m 11.722 BML m 364.846 GMt corrected m 4.144 GML corrected m 357.269 KMt m 22.73 KML m 375.855 Immersion (TPc) tonne/cm 166.526 MTc tonne.m 4275.875 RM at 1deg = GMt.Disp.sin(1) tonne.m 26418.615 Max deck inclination deg 1.9 Trim angle (+ve by stern) deg -0.1


Graph 2.6

-2

-1

0

1

2

3

4

-25 0 25 50 75 100




GZ

m


g) Dcase 7



Fig 2.7

RESULT



(GZ st1) / GZmax = 0.059571/3.372 =.0177 < 0.6 (PASS) Ratio of areas type 2 - general wind heeling arm Pass Heeling arm = A cos^n(phi) A = 0.064 m n = 2 gust ratio 1 Area1 integrated from the greater of spec. heel angle 0 deg angle of equilibrium (with heel arm) 2.8 deg 2.8 to the lesser of spec. heel angle 70 deg angle of first GZ peak 58 deg angle of max. GZ 58 deg 58 angle of max. GZ above heel arm 58.5 deg first downflooding angle n/a deg angle of vanishing stability (with heel arm) 103.4 deg Area2 integrated to the lesser of roll back angle from equilibrium (with heel arm)

25.0 (-22.2) deg -22.2

Area1 / Area2 shall be greater than (>) 140 % 414.14 Pass Intermediate values Equilibrium angle with heel arm deg 2.8 Area1 (under GZ), from 2.8 to 58.0 deg. m.deg 99.276 Area1 (under HA), from 2.8 to 58.0 deg. m.deg 2.347 Area1, from 2.8 to 58.0 deg. m.deg 96.93


Area2 (under GZ), from -22.2 to 2.8 deg. m.deg -21.97 Area2 (under HA), from -22.2 to 2.8 deg. m.deg 1.435 Area2, from -22.2 to 2.8 deg. m.deg 23.405





Graph 2.7

h) Dcase 8



Fig 2.8

RESULT



(GZ st1) / GZmax = 0.060571/3.367 =.018 < 0.6 (PASS)

Ratio of areas type 2 - general wind heeling arm Pass Heeling arm = A cos^n(phi) A = 0.064 m

-2

-1

0

1

2

3

4

-25 0 25 50 75 100




GZ

m


n = 2 gust ratio 1 Area1 integrated from the greater of spec. heel angle 0 deg angle of equilibrium (with heel arm) 2.8 deg 2.8 to the lesser of spec. heel angle 70 deg angle of first GZ peak 58 deg angle of max. GZ 58 deg 58 angle of max. GZ above heel arm 58.5 deg first downflooding angle n/a deg angle of vanishing stability (with heel arm) 103.4 deg Area2 integrated to the lesser of roll back angle from equilibrium (with heel arm)

25.0 (-22.2) deg -22.2



Draft Amidsh. m 21.982 Displacement tonne 365264 Heel to Starboard degrees 1.9 Draft at FP m 22.087 Draft at AP m 21.878 Draft at LCF m 21.982 Trim (+ve by stern) m -0.209 WL Length m 305.2 WL Beam m 56.553 Wetted Area m^2 32501.435 Waterpl. Area m^2 16243.228 Prismatic Coeff. 0.935 Block Coeff. 0.896 Midship Area Coeff. 0.958 Waterpl. Area Coeff. 0.941 LCB from Amidsh. (+ve fwd) m -0.015 LCF from Amidsh. (+ve fwd) m -0.288


KB m 11.008 KG fluid m 18.554 BMt m 11.722 BML m 367.785 GMt corrected m 4.144 GML corrected m 360.207 KMt m 22.73 KML m 378.793 Immersion (TPc) tonne/cm 166.526 MTc tonne.m 4310.965 RM at 1deg = GMt.Disp.sin(1) tonne.m 26417.603 Max deck inclination deg 1.9 Trim angle (+ve by stern) deg 0


Graph 2.8

i) Dcase 9



-2

-1

0

1

2

3

4

-25 0 25 50 75 100




GZ

m


Fig 2.9

RESULT



(GZ st1) / GZmax = 0.06102/3.364 =.0181 < 0.6 (PASS)

Ratio of areas type 2 - general wind heeling arm Pass Heeling arm = A cos^n(phi) A = 0.064 m n = 2 gust ratio 1 Area1 integrated from the greater of spec. heel angle 0 deg angle of equilibrium (with heel arm) 2.8 deg 2.8 to the lesser of spec. heel angle 70 deg angle of first GZ peak 58 deg angle of max. GZ 58 deg 58 angle of max. GZ above heel arm 58.5 deg first downflooding angle n/a deg angle of vanishing stability (with heel arm) 103.4 deg Area2 integrated to the lesser of roll back angle from equilibrium (with heel arm)

25.0 (-22.2) deg -22.2

Area1 / Area2 shall be greater than (>) 140 % 415.157 Pass Intermediate values Equilibrium angle with heel arm deg 2.8 Area1 (under GZ), from 2.8 to 58.0 deg. m.deg 99.305 Area1 (under HA), from 2.8 to 58.0 deg. m.deg 2.347 Area1, from 2.8 to 58.0 deg. m.deg 96.958 Area2 (under GZ), from -22.2 to 2.8 deg. m.deg -21.92 Area2 (under HA), from -22.2 to 2.8 deg. m.deg 1.435


Area2, from -22.2 to 2.8 deg. m.deg 23.354 Table 2.17: Dynamical Stability

Draft Amidsh. m 21.982 Displacement tonne 365263 Heel to Starboard degrees 1.9 Draft at FP m 22.018 Draft at AP m 21.946 Draft at LCF m 21.982 Trim (+ve by stern) m -0.072 WL Length m 305.2 WL Beam m 56.553 Wetted Area m^2 32502.709 Waterpl. Area m^2 16243.224 Prismatic Coeff. 0.938 Block Coeff. 0.899 Midship Area Coeff. 0.958 Waterpl. Area Coeff. 0.941 LCB from Amidsh. (+ve fwd) m 1.208 LCF from Amidsh. (+ve fwd) m 1.059 KB m 11.007 KG fluid m 18.554 BMt m 11.722 BML m 364.526 GMt corrected m 4.144 GML corrected m 356.947 KMt m 22.73 KML m 375.533 Immersion (TPc) tonne/cm 166.526 MTc tonne.m 4271.937 RM at 1deg = GMt.Disp.sin(1) tonne.m 26417.1 Max deck inclination deg 1.9 Trim angle (+ve by stern) deg 0

Table 2.18: Table for equilibrium analysis


Graph 2.9

j) Dcase 10



Fig 2.10

RESULT



(GZ st1) / GZmax = 0. 058367/3.36 =.0174 < 0.6 (PASS) Ratio of areas type 2 - general wind heeling arm Pass

-2

-1

0

1

2

3

4

-25 0 25 50 75 100




GZ

m


Heeling arm = A cos^n(phi) A = 0.064 m n = 2 gust ratio 1 Area1 integrated from the greater of spec. heel angle 0 deg angle of equilibrium (with heel arm) 2.8 deg 2.8 to the lesser of spec. heel angle 70 deg angle of first GZ peak 58 deg angle of max. GZ 58 deg 58 angle of max. GZ above heel arm 58 deg first downflooding angle n/a deg angle of vanishing stability (with heel arm) 103.5 deg Area2 integrated to the lesser of roll back angle from equilibrium (with heel arm)

25.0 (-22.2) deg -22.2



Draft Amidsh. m 21.982 Displacement tonne 365262 Heel to Starboard degrees 1.9 Draft at FP m 21.958 Draft at AP m 22.006 Draft at LCF m 21.982 Trim (+ve by stern) m 0.048 WL Length m 305.2 WL Beam m 56.553 Wetted Area m^2 32504.577 Waterpl. Area m^2 16243.224 Prismatic Coeff. 0.939 Block Coeff. 0.899 Midship Area Coeff. 0.958 Waterpl. Area Coeff. 0.941


LCB from Amidsh. (+ve fwd) m 2.453 LCF from Amidsh. (+ve fwd) m 2.407 KB m 11.007 KG fluid m 18.554 BMt m 11.722 BML m 358.114 GMt corrected m 4.144 GML corrected m 350.536 KMt m 22.73 KML m 369.122 Immersion (TPc) tonne/cm 166.526 MTc tonne.m 4195.195 RM at 1deg = GMt.Disp.sin(1) tonne.m 26416.614 Max deck inclination deg 1.9 Trim angle (+ve by stern) deg 0


Graph 2.10

k) Dcase 11



-2

-1

0

1

2

3

4

-25 0 25 50 75 100




GZ

m


Fig 2.11

RESULT



(GZ st1) / GZmax = 0. 056122/3.405 =.0165 < 0.6 (PASS) Ratio of areas type 2 - general wind heeling arm Pass Heeling arm = A cos^n(phi) A = 0.065 m n = 2 gust ratio 1 Area1 integrated from the greater of spec. heel angle 0 deg angle of equilibrium (with heel arm) 0.2 deg 0.2 to the lesser of spec. heel angle 70 deg angle of first GZ peak 57 deg angle of max. GZ 57 deg angle of max. GZ above heel arm 57 deg 57 first downflooding angle n/a deg angle of vanishing stability (with heel arm) n/a deg Area2 integrated to the lesser of roll back angle from equilibrium (with heel arm)

25.0 (-24.8) deg -24.8




Draft Amidsh. m 21.766 Displacement tonne 362441 Heel to Starboard degrees -0.6 Draft at FP m 22.101 Draft at AP m 21.431 Draft at LCF m 21.775 Trim (+ve by stern) m -0.67 WL Length m 305.201 WL Beam m 56.523 Wetted Area m^2 32344.951 Waterpl. Area m^2 16229.142 Prismatic Coeff. 0.928 Block Coeff. 0.917 Midship Area Coeff. 0.987 Waterpl. Area Coeff. 0.941 LCB from Amidsh. (+ve fwd) m 4.521 LCF from Amidsh. (+ve fwd) m 3.794 KB m 10.883 KG fluid m 18.662 BMt m 11.788 BML m 350.871 GMt corrected m 4.02 GML corrected m 343.103 KMt m 22.671 KML m 361.754 Immersion (TPc) tonne/cm 166.381 MTc tonne.m 4074.532 RM at 1deg = GMt.Disp.sin(1) tonne.m 25429.351 Max deck inclination deg 0.6 Trim angle (+ve by stern) deg -0.1



Graph 2.11

l) Dcase 12

Tanks Damaged: Ballast starboard 1, Ballast bottom 1.1,Cargo1.1, ER Ballast starboard 2, ER

Ballast bottom 2.1, ER Ballast bottom 2.2.

Fig 2.12

RESULT



(GZ st1) / GZmax = 0. 051/3.368 =.0151 < 0.6 (PASS) Ratio of areas type 2 - general wind heeling arm Pass Heeling arm = A cos^n(phi) A = 0.059 m n = 2

-2

-1

0

1

2

3

4

-25 0 25 50 75 100




GZ

m


gust ratio 1 Area1 integrated from the greater of spec. heel angle 0 deg angle of equilibrium (with heel arm) 0.1 deg 0.1 to the lesser of spec. heel angle 70 deg angle of first GZ peak 55.5 deg angle of max. GZ 55.5 deg 55.5 angle of max. GZ above heel arm 55.5 deg first downflooding angle n/a deg angle of vanishing stability (with heel arm) 99.9 deg Area2 integrated to the lesser of roll back angle from equilibrium (with heel arm)

25.0 (-24.9) deg -24.9



Draft Amidsh. m 21.824 Displacement tonne 378010 Heel to Starboard degrees -0.7 Draft at FP m 22.036 Draft at AP m 21.613 Draft at LCF m 21.824 Trim (+ve by stern) m -0.423 WL Length m 305.2 WL Beam m 56.524 Wetted Area m^2 32388.324 Waterpl. Area m^2 17037.678 Prismatic Coeff. 0.971 Block Coeff. 0.957 Midship Area Coeff. 0.986 Waterpl. Area Coeff. 0.988 LCB from Amidsh. (+ve fwd) m 1.033


LCF from Amidsh. (+ve fwd) m -0.399 KB m 10.992 KG fluid m 18.672 BMt m 12.076 BML m 353.065 GMt corrected m 4.398 GML corrected m 345.387 KMt m 23.068 KML m 364.057 Immersion (TPc) tonne/cm 174.67 MTc tonne.m 4277.841 RM at 1deg = GMt.Disp.sin(1) tonne.m 29016.684 Max deck inclination deg 0.7 Trim angle (+ve by stern) deg -0.1


Graph 2.12

m) Dcase 13

-2

-1

0

1

2

3

4

-25 0 25 50 75 100

Max GZ = 3.368 m at 55.5 deg.



GZ

m


Tanks Damaged: ER, ER Ballast starboard 2, ER Ballast starboard 1, ER Ballast bottom 1.1,ER

Ballast bottom 2.1, Ballast tank Aftmost.

Fig 2.13

RESULT



(GZ st1) / GZmax = 0. 031/3.27 =.0095 < 0.6 (PASS)

Ratio of areas type 2 - general wind heeling arm Pass Heeling arm = A cos^n(phi) A = 0.062 m n = 2 gust ratio 1 Area1 integrated from the greater of spec. heel angle 0 deg angle of equilibrium (with heel arm) 0.4 deg 0.4 to the lesser of spec. heel angle 70 deg angle of first GZ peak 56 deg angle of max. GZ 56 deg angle of max. GZ above heel arm 56 deg 56 first downflooding angle n/a deg angle of vanishing stability (with heel arm) n/a deg Area2 integrated to the lesser of roll back angle from equilibrium (with heel arm)

25.0 (-24.6) deg -24.6

Area1 / Area2 shall be greater than (>) 140 % 413.203 Pass Intermediate values Equilibrium angle with heel arm deg 0.4 Area1 (under GZ), from 0.4 to 56.0 deg. m.deg 101.803 Area1 (under HA), from 0.4 to 56.0 deg. m.deg 2.455 Area1, from 0.4 to 56.0 deg. m.deg 99.348


Area2 (under GZ), from -24.6 to 0.4 deg. m.deg -22.631 Area2 (under HA), from -24.6 to 0.4 deg. m.deg 1.412 Area2, from -24.6 to 0.4 deg. m.deg 24.043


Draft Amidsh. m 22.286 Displacement tonne 377663 Heel to Starboard degrees -0.5 Draft at FP m 21.182 Draft at AP m 23.39 Draft at LCF m 22.267 Trim (+ve by stern) m 2.207 WL Length m 305.208 WL Beam m 56.522 Wetted Area m^2 32743.137 Waterpl. Area m^2 16683.514 Prismatic Coeff. 0.913 Block Coeff. 0.904 Midship Area Coeff. 0.99 Waterpl. Area Coeff. 0.967 LCB from Amidsh. (+ve fwd) m 1.326 LCF from Amidsh. (+ve fwd) m 2.677 KB m 11.225 KG fluid m 18.708 BMt m 11.906 BML m 333.069 GMt corrected m 4.423 GML corrected m 325.586 KMt m 23.13 KML m 344.293 Immersion (TPc) tonne/cm 171.039 MTc tonne.m 4028.894 RM at 1deg = GMt.Disp.sin(1) tonne.m 29152.03 Max deck inclination deg 0.6 Trim angle (+ve by stern) deg 0.4



Graph 2.13

2.2) Intact Stability

a) Completely full case

Time T delta Vw Area z l A

hr m tonne knot m2 m m

48 8.985 157829 100 9957.593 26.59718298 22.10468 0.237083

43.2 9.827 172789 100 9700.6146 27.05259358 22.13909 0.211296

38.4 11.253 197673 100 9265.3994 27.82822466 22.20172 0.17691

33.6 12.112 212744 100 9003.2326 28.29837501 22.24238 0.160019

28.8 13.562 238227 100 8560.6926 29.09764175 22.31664 0.136331

24 14.289 251005 100 8338.8122 29.50134444 22.35684 0.126264

19.2 15.72 276123 100 7902.071 30.30257354 22.44257 0.109184

14.4 16.538 290498 100 7652.4174 30.7649743 22.49597 0.100742

9.6 18.242 320417 100 7132.3566 31.74021996 22.61922 0.085594

4.8 20.062 352405 100 6576.8926 32.80338207 22.77238 0.07225

0 22.066 386546 100 5965.2718 34.00702383 22.97402 0.060272 Table 2.27: Complete full case

0 hr:

-2

-1

0

1

2

3

4

-25 0 25 50 75 100




GZ

m


Graph 2.14

Max GZ = 3.632 : Area1/Area2 shall be greater than (>) 140 % = 413.698 (PASS)

4.8 hr:

Graph 2.15



9.6 hr:

Graph 2.16


14.4 hr:

Graph 2.17



19.2 hr:

Graph 2.18


24 hr:

Graph 2.19



28.8 hr:

Graph 2.20


33.6 hr:

Graph 2.21



38.4 hr:

Graph 2.22


43.2 hr:

Graph 2.23



48 hr:

Graph 2.24


b) Day 6 type



0 13.871 243662 100 8466.3858 29.26897179 22.33347 0.131921

4.8 12.594 221221 100 8856.1262 28.56323875 22.26624 0.151535

9.6 11.35 199364 100 9235.795 27.88119939 22.2062 0.174884

14.4 11.806 207386 100 9096.6238 28.13062553 22.22763 0.165746

19.2 11.142 195724 100 9299.2766 27.76763904 22.19664 0.179284

24 11.034 193812 100 9332.2382 27.70872632 22.19173 0.181654

Table 2.28: Day 6 type

0 hr:


Graph 2.25


4.8 hr:

Graph 2.26



9.6 hr:

Graph 2.27


14.4 hr:

Graph 2.28



19.2 hr:

Graph 2.29


24 hr:

Graph 2.30



c) Day 11 type



0 15.675 275345 100 7915.805 30.27723359 22.43973 0.109669

4.8 14.658 257476 100 8226.1934 29.70707967 22.37808 0.121544

9.6 13.575 238474 100 8556.725 29.10484233 22.31734 0.136131

14.4 12.57 220815 100 8863.451 28.55003177 22.26503 0.151931

19.2 11.59 203598 100 9162.547 28.01239517 22.2174 0.169975

24 11.344 199261 100 9237.6262 27.87792177 22.20592 0.175007 Table 2.29: Day 11 type

0 hr:

Graph 2.31


4.8 hr:


Graph 2.32


9.6 hr:

Graph 2.33


14.4 hr:


Graph 2.34


19.6 hr:

Graph 2.35


24 hr:


Graph 2.36


2.3) International Convention for the Safety of Life at Sea, 1974(SOLAS)

Chapter II-1, paper B-1

Regulation 25-1:

1. The requirements in this part shall apply to cargo ships over 100 m in length (Ls) but shall exclude those ships which are shown to comply with subdivision and damage stability regulations in other instruments developed by the Organization.

2. Any reference hereinafter to regulations refers to the set of regulations contained in this part.

3. The administration may for a particular ship or ground of ships accepts alternative arrangements, if it is satisfied that at least the same degree of safety as represented by these regulations is achieved. Any administration which allows such alternative arrangements shall communicate to the organization particulars thereof.

Requirements 25-2:

For the purpose of these regulations, unless expressly provided otherwise: Subdivision load lone is a waterline used in determining the subdivision of the ship.

1.2 Deepest subdivision load lone is the subdivision load line which corresponds to the summer draught to be assigned to the ship.


1.3 Partial load line is the light ship draught plus 60% of the difference between the light ship draught and deepest subdivision load line.

2.1 Subdivision length of the ship (Ls) is the greatest projected moulded length of that part of the ship at or below deck or decks limiting the vertical extent of flooding with the ship at the deepest subdivision load line. 2.2 Mid-length is the mid-point of the subdivision length of the ship. 2.3 Aft terminal is the aft limit of the subdivision length. 2.4 Forward terminal is the forward limit of the subdivision length. 3 Breadth (B) is the greatest moulded breadth of the ship at or below the deepest subdivision load line. 4 Draught (d) is the vertical distance from the moulded baseline at mid-length to the waterline in question. 5 Permeability () of a space is the proportion of the immersed volume of that space which can be occupied by water. Regulation 25-3: 1. These regulations are intended to provide ships with a minimum standard of subdivision. 2. The degree of subdivision to be provided shall be determined by the required subdivision index R, as follows: R = (0.002 + 0.0009Ls) 1/3 where Ls is in meters. Regulation 25-4: 1. The attained subdivision index A, calculated in accordance with thios regulation, shall not be less than the required subdivision index R, calculated in accordance with paragraph 2 of regulation 25-3. 2. The attained subdivision index A shall be calculated for the ship by the following formula: A = pi si Where: i – represents each compartment or group of compartments under consideration. pi – accounts for the probability that only the compartment or group of compartments under consideration may be flooded, disregarding any horizontal subdivision, si – accounts for the probability of survival after flooding the compartment or group of compartments under consideration, including the effects of any horizontal subdivision.


3. In calculating A, level trim shall be used. 4. This summation covers only those cases of flooding which contribute to the value of the attained subdivision index A. 5. The summation indicated by the above formula shall be taken over the ship’s length for all cases of flooding in which a single compartment or two or more adjacent compartments are involved. 6. Wherever wing compartments are fitted, contribution to be summation indicated by the formula shall be taken for all cases of flooding in which wing compartments are involved; and additionally, for all cases of simultaneous flooding or a wing compartment or compartments, be the adjacent inboard compartment or compartments assuming a rectangular penetration which extends to the ship’s centerline, but excludes damage to any centerline bulkhead. 7. The assumed vertical extent of damage is to extend from the baseline upwards to any watertight horizontal subdivision above the waterline or higher. However, if a lesser extent will give a more severe result, such extent is to be assumed. 8. If pipes, ducts or tunnels are situated within assumed flooded compartments, arrangements are to be made to ensure that progressive flooding cannot thereby extend to compartments other than those assumed flooded. However, the administration may permit minor progressive flooding if it is demonstrated that its effects can be easily controlled and the safety of the ship is not impaired. 9. In the flooding calculations carried out according to the regulation only one breach of the hull need to be assumed. Regulation 25-5: 1. The factor pi shall be calculated according to paragraph 1.1 as appropriate, using the following notations: x1 = the distance from the aft terminal of Ls to the foremost portion of the aft end of the compartment being considered; x2 = the distance from the aft terminal of Ls to the aftermost portion of the forward end of the compartment being considered;

E1 = x1 / Ls ; E2 = x2 / Ls ; E = E1 + E2 -1 J = E2 – E1

J’ = J – E, if E0 J’ = J + E, if E<0

The maximum non-dimensional damage length

Jmax = 48/Ls , but not more than 0.24.


The assumed distribution density of damage location along the ship’s length

a = 1.2 + 0.8 E, but not more than 1.2. The assumed distribution function of damage location along the ship’s length

F = 0.4 + 0.25E (1.2 + a) Y = J/ Jmax p = F1 Jmax q = 0.4 F2 (Jmax)

2

F1 = y2- y3/3 if y<1 F1 = y – 1/3 otherwise F2 = y3/3 – y4/12 if y<1 F2 = y2/2 – y/3 + 1/12 otherwise

1.1 The factor pi is determined for each single compartment. 1.1.1 Where the compartment considered extends over the entire ship length Ls: pi = 1 1.1.2 Where the aft limit of the compartment considered coincides with the aft terminal: pi = F + 0.5ap + q 1.1.3 Where the forward limit of the compartment considered coincides with the forward terminal: pi = 1 – F +0.5ap 1.1.4 When both ends of the compartment considered are inside the aft and forward terminals of the ship length Ls: pi = ap 1.1.5 In applying the formulae of paragraphs 1.1.2, 1.1.3 and 1.1.4, where the compartment considered extends over the mid-length, these formulae values shall be reduced by an amount determined according to the formulae for q, in which F2 is calculated taking ‘y’ to be J/ Jmax . 2 Wherever wing compartments are fitted, the pi value for a wing compartment shall be obtained by multiplying the value, as determined in paragraph 3, by the reduction factor r according to paragraph 2.2, which represents the probability that the inboard spaces will not be flooded. 2.1 The pi value for the case of simultaneous flooding of a wing and adjacent inboard compartment shall be obtained by using the formulae of paragraph 3, multiplied by the factor (1-r). 2.2 The reduction factor r shall be determined by the following formulae:


For J 0.2 b/B: r = b/B (2.3 + 0.08/ (J + 0.02)) + 0.1, if b/B 0.2 r = 0.016/ (J + 0.02) + b/B + 0.36, if b/B > 0.2 For J < 0.2 b/B the reduction factor r shall be determined by linear interpolation between: r = 1, for J = 0 and r = as for the case where J 0.2 b/B for J = 0.2 b/B, where: b = the mean transverse distance in meters measured at right angles to the centerline at the deepest subdivision load line between the shell and a plane through the outermost portion of and parallel to that part of the longitudinal bulkhead which extends between the longitudinal limits used in calculating the factor pi . 3 To evaluate pi for the compartments taken singly the formulae in paragraphs 1 and 2 shall be applied directly. 3.1 To evaluate the pi values attributable to groups of compartments the following applies: for compartments taken by pairs: pi = p12 – p1 – p2 pi = p23 – p2 – p3 etc for compartments taken by groups of three: pi = p123 – p12 – p23 + p2 pi = p234 – p23 – p34 + p3 etc. for compartments taken by groups of four: pi = p1234 – p123 – p234 + p23 pi = p2345 – p234 – p345 + p34 etc. where: p12, p23, p34 etc., p123, p234, p345 etc., and p1234, p2345, p3456 etc. shall be calculated according to the formulae in paragraphs 1 and 2 for a single compartment whose non-dimensional length J corresponds to that of a group consisting of the compartments indicated by the indices assigned to p. 3.2 The factor pi for a group of three or more adjacent compartments equals zero if the non-dimensional length of such a group minus the non-dimensional length of the aftermost and foremost compartments in the group is greater than Jmax. Requirements 25-6: 1 The factor si shall be determined for each compartment or group of compartments according to the following:


1.1 In general for any condition of flooding from any initial loading condition s shall be: s = C 0.5 (GZmax) (range) with: C = 1, if e 25 deg, C = 0, if e > 30 deg, C = (30- e ) /5 otherwise GZmax = maximum positive righting lever (meters) within the range as given below but not more than 0.1 m; Range = range of positive righting levers beyond the angle of equilibrium (degrees) but not more than 20 deg, however, the range shall be terminated at the angle where openings are not capable of being closed weather-tight are immersed. e = final equilibrium angle of heel (degrees) 1.2 s = 0 where the final waterline taking into account sinkage, heel and trim, immerses the lower edge of openings through which progressive flooding may take place. Such opening shall include air-pipes, ventilators and openings which are closed by means of weather-tight doors or hatch covers, and may exclude those openings closed by means of watertight manhole covers and flush scuttles, small watertight hatch covers which maintain the high integrity of the deck, remotely operated watertight doors, access doors and access hatch covers of watertight integrity, normally closed at sea and side scuttles of the non-opening type. However, if the compartments so flooded are taken into account in the calculations the requirements of this regulation shall be applied. 1.3 For each compartment or group of compartments si shall be weighted according to draught considerations as follows: si = 0.5 sl + 0.5 sp where: sl = s-factor at the deepest subdivision load line. sp = s-factor at the partial load line 2 For all compartments forward of the collision bulkhead, the s- value, calculated assuming the ship to be at its deepest subdivision load line and with assumed unlimited vertical extent of damage, is to be equal to 1. 3 Wherever a horizontal subdivision is fitted above the waterline in question the following applies. 3.1 The s-value for the lower compartment or group of compartments shall be obtained by multiplying the value as determined in paragraph 1.1 by the reduction factor v according to paragraph 3.3, which represents the probability that the spaces above the horizontal subdivision will not be flooded.


3.2 In cases of positive contribution to index A due to simultaneous flooding of the spaces above the horizontal subdivision the resulting s-value for such a compartment or group of compartments shall be obtained by an increase of the value as determined by paragraph 3.1 by the s-value for simultaneous flooding according to paragraph 1.1, multiplied by the factor (1-v). 3.3 The probability factor vi shall be calculated according to: vi = (H-d)/ (Hmax – d) for the assumed flooding up to the horizontal subdivision load line, where H is to be restricted to a height of Hmax . vi = 1, if the uppermost horizontal subdivision in way of the assumed damaged region is below Hmax . where: H = is the height of the horizontal subdivision above the baseline (meters) which is assumed to limit the vertical extent of damage. Hmax = is the maximum possible vertical extent of damage above the baseline (meters), or Hmax = d + 0.056 Ls (1-Ls/500), if Ls250 m Hmax = d + 7, if Ls>250 m whichever is less. Regulation 25-7: For the purpose of the subdivision and damage stability calculations of the regulations, the permeability of each space or part of a space shall be as follows: Spaces Permeability Appropriated to stores 0.60 Occupied by accommodation 0.95 Occupied by machinery 0.85 Void spaces 0.95 Dry cargo spaces 0.70 Intended for liquid 0 or 0.95 Regulation 25-8: 1 The master of the ship shall be supplied with such reliable information as is necessary to enable him by rapid and simple means to obtain accurate guidance as to the stability of the ship under varying conditions of service. The information shall include: a curve of minimum operational height (GM) versus draught which assumes compliance with the relevant intact stability requirements of regulation 25-1 to 25-6, alternatively a corresponding curve of the maximum allowable vertical centre of gravity (KG) versus draught, or with the equivalents of either of those curves; instructions concerning the operation of cross-flooding arrangements; and all other data and aids which might be necessary to maintain stability after damage.


2 There shall be permanently exhibited or readily available on the navigating bridge, for the guidance of the officer in charge of the ship plans showing clearly for each deck and hold the boundaries of the watertight compartments, the openings therein with the means of closure and position of any controls thereof, and arrangements for the correction of any list due to flooding, In addition, booklets containing the afore mentioned information shall be made available to the officers of the ship. 3 In order to provide the information referred to in paragraph 1.1, the limiting GM (or KG) values to be used, if they have been determined from the considerations related to the subdivision index, the limiting GM shall be varied linearly between the deepest subdivision load line and the partial load line. In such cases, for draughts below the partial load line if the minimum GM requirement at this draught results from the calculation of the subdivision index, then this GM value shall be assumed for lesser draughts, unless the intact stability requirements apply. Requirement 25-9: 1 The number of openings in watertight subdivisions is to be kept to a minimum compatible with the design and proper working of the ship. Where penetration of watertight bulkheads and internal decks are necessary for access, piping, ventilation, electrical cables, etc., arrangements are to be made to maintain the watertight integrity. The administration may permit relaxation in the watertight-ness of openings above the freeboard deck, provided that it is demonstrated that any progressive flooding can be easily controlled and that the safety of the ship is not impaired. 2 Doors provided to ensure the watertight integrity of internal openings which are used while at sea to be sliding watertight doors capable of being remotely closed from the bridge and are also to be operated locally from each side of the bulkhead. Indicators are to be provided at the control position showing whether the doors are open or closed, and an audible alarm is to be provided at the door closure. The power, control and indicators are to be operable in the event of main power failure. Particular attention is to be paid to minimizing the effect of control system failure. Each power-operated sliding watertight door shall be provided with an individual hand-operated mechanism. It shall be possible to open and close the door by hand at the door itself from both sides. 3 Access doors and access hatch covers normally closed at sea, intended to ensure the watertight integrity of internal openings, shall be provided with means of indication locally, and on the bridge showing whether these doors or hatch covers are open or closed. A notice has to be affixed to each such door or hatch cover to the effect that it is not be left open. The use of such doors and hatch covers shall be authorized by the officer of the watch. 4 Watertight doors or ramps of satisfactory construction may be fitted to internally subdivide large cargo spaces, provided that the administration is satisfied that such doors or ramps are essential. These doors or ramps may be hinged, rolling or sliding doors or ramps, but shall not be remotely controlled. Such doors or ramps shall be closed before the voyage commences and shall be kept closed during navigation. The time of opening such doors and ramps in port and of closing them before the ship leaves port shall be entered in the log book. Should any of the doors or ramps be accessible during the voyage, they shall be fitted with a device which prevents unauthorized opening. 5 Other closing appliances which are kept permanently closed at sea to ensure the watertight integrity of internal opening shall be provided with a notice which is to be affixed to each such closing appliance to the effect that it is to be closed. Manholes fitted with closely bolted covers need not be so marked.


Requirement 25-10: 1 All external openings leading to compartments assumed intact in damage analysis, which are below the final damage waterline and required to be watertight. 2 External openings required to be watertight in accordance with paragraph 1 shall be of sufficient strength and, except for cargo hatch covers, shall be fitted with indicators on the bridge. 3 Openings in the shell plating below the deck limiting the vertical extent of damage shall be kept permanently closed while at sea. Should any of the openings be accessible during the voyage, they shall be fitted with a device which prevents unauthorized opening. 4 Notwithstanding the requirements of paragraph 3, the administration may authorize that particular doors may be opened at the discretion of the master, if necessary for the operation of the ship and provided that the safety of the ship is not impaired. 5 Other closing appliances which are kept permanently closed at sea to ensure the watertight integrity of external openings shall be provided with a notice affixed to each appliance to the effect that it is to be kept closed. Manholes fitted with closely bolted covers need not be so marked. 2.4 Draft and Weight Calculation for Full Load And Ballast Cases:


Fig. Modelled FPSO in Hydromax

Full Load Case (all cargo tanks full, heel and trim 0deg)

Tank and Load Distribution

Item Name Quantity Weight (tonne) Long. Arm

Vertical Arm

Transverse Arm

Free Surface moment FSM type

Lightship 1 26000 152.6 15 0 0

Machinery 1 2542 24.6 10 0 0

Accommodation 1 1803 23 35.8 0 0

m03 tpr1 1 193.1 62.72 36.306 0 0

m03 tpr2/1 1 226.4 77.4 36.488 0 0

m03 tpr2/2 1 226.4 93.3 36.488 0 0

m03 tpr3/1 1 226.4 109.2 36.488 0 0

m03 tpr3/2 1 226.4 125.1 36.488 0 0

m03 mpr1 1 539.5 143.421 42.368 0.021 0

m03 mpr2 1 829.2 166.051 46.522 -0.684 0

m03 mpr3 1 546.1 185.81 42.442 -0.022 0

m03 mpr4 1 542.8 207.06 42.532 -0.021 0

m03 tpr4/1 1 263.1 225.755 37.696 0.361 0

m03 tpr4/2 1 263.1 241.655 37.696 0.036 0

m03 tpr5 1 223.1 257.363 36.998 0.211 0

m33 1 2284 165.746 39.836 14.482 0


m31 1 5028 197.706 44.786 15.791 0

m34 1 1848 164.868 29.05 30.322 0

m51 1 2717 95.503 41.426 -16.738 0

m10 1 1858 120.175 37.3 -15.534 0

m06 1 1858 135.325 37.296 -15.534 0

m23 1 2174 194.568 39.996 -15.705 0

m13 1 1179 218.684 40.972 -14.399 0

m12 1 2031 164.859 39.076 -16.313 0

m42 1 2503 124.894 41.1 15.892 0

m01 1 126.7 275.722 59.653 10.106 0

Turret 1 2000 315.2 29 0 0

Ballast bottom1.1 98% 1145 53.4 1.225 18.51 0 Maximum

Ballast bottom1.2 98% 1028 53.4 1.225 0 0 Maximum

Ballast bottom1.3 98% 1145 53.4 1.225 -18.51 0 Maximum

Ballast bottom2.1 2% 23.08 77.85 0.025 18.51 15393.504 Maximum

Ballast bottom2.2 2% 20.73 77.85 0.025 0 11164.416 Maximum

Ballast bottom2.3 2% 23.08 77.85 0.025 -18.51 15393.504 Maximum





















Ballast bottom9.3 2% 23.31 248.075 0.025 -18.51 15551.874 Maximum Ballast bottom10.1 2% 22.79 272.35 0.025 18.51 15203.459 Maximum Ballast bottom10.2 2% 20.48 272.35 0.025 0 11026.582 Maximum



Ballast port1 98% 1602 53.4 15.877 27.01 0 Maximum

Ballast starboard1 98% 1602 53.4 15.877 -27.01 0 Maximum

Ballast port2 2% 32.31 77.85 2.773 27.01 32.438 Maximum

Ballast starboard2 2% 32.31 77.85 2.773 -27.01 32.438 Maximum









Ballast por7 2% 32.31 199.35 2.773 27.01 32.438 Maximum






Ballast port10 2% 31.91 272.35 2.773 27.01 32.037 Maximum Ballast starboard10 2% 31.91 272.35 2.773 -27.01 32.037 Maximum

Cargo 1.1 98% 9442 53.4 15.877 17.26 0 Maximum

Cargo 1.2 98% 9731 53.4 15.877 0 0 Maximum

Cargo 1.3 98% 9442 53.4 15.877 -17.26 0 Maximum

Cargo 2.1 98% 9327 77.85 15.877 17.26 0 Maximum

Cargo 2.2 98% 9612 77.85 15.877 0 0 Maximum

Cargo 2.3 98% 9327 77.85 15.877 -17.26 0 Maximum

Cargo 3.1 98% 9327 102.15 15.877 17.26 0 Maximum

Cargo 3.2 98% 9612 102.15 15.877 0 0 Maximum

Cargo 3.3 98% 9327 102.15 15.877 -17.26 0 Maximum

Cargo 4.1 98% 9327 126.45 15.877 17.26 0 Maximum

Cargo 4.2 98% 9612 126.45 15.877 0 0 Maximum

Cargo 4.3 98% 9327 126.45 15.877 -17.26 0 Maximum

Cargo5.1 98% 9327 150.75 15.877 17.26 0 Maximum

Cargo 5.2 98% 9612 150.75 15.877 0 0 Maximum

Cargo 5.3 98% 9327 150.75 15.877 -17.26 0 Maximum

Cargo6.1 98% 9327 175.05 15.877 17.26 0 Maximum

Cargo 6.2 98% 9612 175.05 15.877 0 0 Maximum

Cargo 6.3 98% 9327 175.05 15.877 -17.26 0 Maximum

Cargo7.1 98% 9327 199.35 15.877 17.26 0 Maximum


Cargo 7.2 98% 9612 199.35 15.877 0 0 Maximum

Cargo 7.3 98% 9327 199.35 15.877 -17.26 0 Maximum

Cargo8.1 98% 9327 223.65 15.877 17.26 0 Maximum

Cargo8.2 98% 9612 223.65 15.877 0 0 Maximum

Cargo 8.3 98% 9327 223.65 15.877 -17.26 0 Maximum

Cargo9.1 98% 9423 248.075 15.877 17.26 0 Maximum

Cargo 9.2 98% 9711 248.075 15.877 0 0 Maximum

Cargo 9.3 98% 9423 248.075 15.877 -17.26 0 Maximum

Cargo10.1 98% 9212 272.35 15.877 17.26 0 Maximum

Cargo 10.2 98% 9493 272.35 15.877 0 0 Maximum

Cargo 10.3 98% 9212 272.35 15.877 -17.26 0 Maximum

Slop tank1 50% 2264 289.975 9.325 17.26 4205.221 Maximum

Slop tank2 50% 2334 289.975 9.325 0 4603.036 Maximum

Slop tank3 50% 2264 289.975 9.325 -17.26 4205.221 Maximum

Slop ballast 1.1 2% 10.68 289.975 0.025 18.51 7126.621 Maximum

Slop ballast 1.2 2% 9.598 289.975 0.025 0 5168.71 Maximum

Slop ballast 1.3 2% 10.68 289.975 0.025 -18.51 7126.621 Maximum

Slop ballast port 2% 14.96 289.975 2.773 27.01 15.018 Maximum Slop ballast starboard 2% 14.96 289.975 2.773 -27.01 15.018 Maximum ER ballast bottom1.1 98% 1011 17.1 1.225 14.13 0 Maximum ER ballast bottom1.2 98% 1011 17.1 1.225 -14.13 0 Maximum ER ballast bottom2.1 98% 1113 32.85 1.225 14.13 0 Maximum ER ballast bottom2.2 98% 1113 32.85 1.225 -14.13 0 Maximum

ER ballast port1 98% 977.1 17.1 15.877 27.01 0 Maximum ER ballast starboard1 98% 977.1 17.1 15.877 -27.01 0 Maximum

ER ballast port2 98% 1075 32.85 15.877 27.01 0 Maximum ER ballast starboard2 98% 1075 32.85 15.877 -27.01 0 Maximum

FW 50% 259.9 4.8 25.3 4.75 685.864 Maximum

FW 50% 259.9 4.8 25.3 -4.75 685.864 Maximum

Diesel tank 50% 4321 13.45 9.325 0 73708.28 Maximum Ballast tank forward FP 25% 3044 299.95 3.726 0 77878.977 Maximum Ballast Tank aft A.P. 98% 11517 4.8 11.172 0 0 Maximum

Total Weight= 386360 LCG=153.102 VCG=16.938 TCG=0.002 563484.67

FS corr.=1.458

VCG fluid=18.396


Equilibrium Result

Draft Amidsh. m 22

Displacement tonne 386360

Heel to Starboard degrees 0

Draft at FP m 22.675

Draft at AP m 21.323

Draft at LCF m 21.995

Trim (+ve by stern) m -0.352

WL Length m 305.203

WL Beam m 56.52

Wetted Area m^2 32499.554

Waterpl. Area m^2 17134.339

Prismatic Coeff. 0.965

Block Coeff. 0.963

Midship Area Coeff. 1

Waterpl. Area Coeff. 0.993

LCB from Amidsh. (+ve fwd) m 0.534

LCF from Amidsh. (+ve fwd) m -1.009

KB m 11.001

KG fluid m 18.396

BMt m 12.003

BML m 348.409

GMt corrected m 4.607

GML corrected m 341.014

KMt m 23.004

KML m 359.41

Immersion (TPc) tonne/cm 175.661

MTc tonne.m 4316.969

RM at 1deg = GMt.Disp.sin(1) tonne.m 31067.323

Max deck inclination deg 0.3

Trim angle (+ve by stern) deg 0

Ballast Load Case ( minimum draft so that FPSO satisfies stability criteria and heel and

trim 0deg )



Vertical Arm

Transverse Arm



Equilibrium Result

Draft Amidsh. m 7.895


Heel to Starboard degrees 0.5

Draft at FP m 8.001

Draft at AP m 8.001


Trim (+ve by stern) m 0

WL Length m 305.2

WL Beam m 56.523




Block Coeff. 0.961

Midship Area Coeff. 0.967


LCB from Amidsh. (+ve fwd) m -1.009


KB m 4

KG fluid m 20.87

BMt m 33.001

BML m 957.812




KMt m 37.001

KML m 961.812





Trim angle (+ve by stern) deg 0

Ballast Only Case(all the ballast tanks filled)



Vertical Arm

Transverse Arm


Lightship 1 26000 152.6 15 0 0

Machinery 1 2542 24.6 10 0 0


m03 tpr1 1 193.1 62.72 36.306 0 0

m03 tpr2/1 1 226.4 77.4 36.488 0 0

m03 tpr2/2 1 226.4 93.3 36.488 0 0

m03 tpr3/1 1 226.4 109.2 36.488 0 0

m03 tpr3/2 1 226.4 125.1 36.488 0 0

m03 mpr1 1 539.5 143.421 42.368 0.021 0

m03 mpr2 1 829.2 166.051 46.522 -0.684 0

m03 mpr3 1 546.1 185.81 42.442 -0.022 0

m03 mpr4 1 542.8 207.06 42.532 -0.021 0

m03 tpr4/1 1 263.1 225.755 37.696 0.361 0

m03 tpr4/2 1 263.1 241.655 37.696 0.036 0

m03 tpr5 1 223.1 257.363 36.998 0.211 0

m33 1 2284 165.746 39.836 14.482 0

m31 1 5028 197.706 44.786 15.791 0

m34 1 1848 164.868 29.05 30.322 0

m51 1 2717 95.503 41.426 -16.738 0

m10 1 1858 120.175 37.3 -15.534 0

m06 1 1858 135.325 37.296 -15.534 0

m23 1 2174 194.568 39.996 -15.705 0

m13 1 1179 218.684 40.972 -14.399 0

m12 1 2031 164.859 39.076 -16.313 0

m42 1 2503 124.894 41.1 15.892 0

m01 1 126.7 275.722 59.653 10.106 0

Turret 1 2000 315.2 29 0 0



Ballast por7 98% 1583 199.35 15.877 27.01 0 Maximum








Cargo 1.1 2% 192.7 53.4 2.773 17.26 8946.646 Maximum

Cargo 1.2 2% 198.6 53.4 2.773 0 9793.002 Maximum

Cargo 1.3 2% 192.7 53.4 2.773 -17.26 8946.646 Maximum

Cargo 2.1 2% 190.3 77.85 2.773 17.26 8837.542 Maximum

Cargo 2.2 2% 196.2 77.85 2.773 0 9673.577 Maximum

Cargo 2.3 2% 190.3 77.85 2.773 -17.26 8837.542 Maximum

Cargo 3.1 2% 190.3 102.15 2.773 17.26 8837.542 Maximum

Cargo 3.2 2% 196.2 102.15 2.773 0 9673.577 Maximum

Cargo 3.3 2% 190.3 102.15 2.773 -17.26 8837.542 Maximum

Cargo 4.1 2% 190.3 126.45 2.773 17.26 8837.542 Maximum

Cargo 4.2 2% 196.2 126.45 2.773 0 9673.577 Maximum

Cargo 4.3 2% 190.3 126.45 2.773 -17.26 8837.542 Maximum

Cargo5.1 2% 190.3 150.75 2.773 17.26 8837.537 Maximum

Cargo 5.2 2% 196.2 150.75 2.773 0 9673.571 Maximum

Cargo 5.3 2% 190.3 150.75 2.773 -17.26 8837.537 Maximum

Cargo6.1 2% 190.3 175.05 2.773 17.26 8837.542 Maximum

Cargo 6.2 2% 196.2 175.05 2.773 0 9673.577 Maximum

Cargo 6.3 2% 190.3 175.05 2.773 -17.26 8837.542 Maximum

Cargo7.1 2% 190.3 199.35 2.773 17.26 8837.542 Maximum

Cargo 7.2 2% 196.2 199.35 2.773 0 9673.577 Maximum

Cargo 7.3 2% 190.3 199.35 2.773 -17.26 8837.542 Maximum

Cargo8.1 2% 190.3 223.65 2.773 17.26 8837.542 Maximum

Cargo8.2 2% 196.2 223.65 2.773 0 9673.577 Maximum

Cargo 8.3 2% 190.3 223.65 2.773 -17.26 8837.542 Maximum

Cargo9.1 2% 192.3 248.075 2.773 17.26 8928.463 Maximum

Cargo 9.2 2% 198.2 248.075 2.773 0 9773.099 Maximum

Cargo 9.3 2% 192.3 248.075 2.773 -17.26 8928.463 Maximum

Cargo10.1 2% 188 272.35 2.773 17.26 8728.436 Maximum

Cargo 10.2 2% 193.7 272.35 2.773 0 9554.149 Maximum

Cargo 10.3 2% 188 272.35 2.773 -17.26 8728.436 Maximum

Slop tank1 2% 90.57 289.975 2.773 17.26 4205.221 Maximum

Slop tank2 2% 93.34 289.975 2.773 0 4603.036 Maximum


Slop tank3 2% 90.57 289.975 2.773 -17.26 4205.221 Maximum

Slop ballast 1.1 98% 523.5 289.975 1.225 18.51 0 Maximum

Slop ballast 1.2 98% 470.3 289.975 1.225 0 0 Maximum

Slop ballast 1.3 98% 523.5 289.975 1.225 -18.51 0 Maximum

Slop ballast port 98% 732.8 289.975 15.877 27.01 0 Maximum Slop ballast starboard 98% 732.8 289.975 15.877 -27.01 0 Maximum ER ballast bottom1.1 98% 1011 17.1 1.225 14.13 0 Maximum ER ballast bottom1.2 98% 1011 17.1 1.225 -14.13 0 Maximum ER ballast bottom2.1 98% 1113 32.85 1.225 14.13 0 Maximum ER ballast bottom2.2 98% 1113 32.85 1.225 -14.13 0 Maximum

ER ballast port1 98% 977.1 17.1 15.877 27.01 0 Maximum ER ballast starboard1 98% 977.1 17.1 15.877 -27.01 0 Maximum

ER ballast port2 98% 1075 32.85 15.877 27.01 0 Maximum ER ballast starboard2 98% 1075 32.85 15.877 -27.01 0 Maximum

FW 2% 10.4 4.8 23.86 4.75 685.864 Maximum

FW 2% 10.4 4.8 23.86 -4.75 685.864 Maximum

Diesel tank 2% 172.8 13.45 2.773 0 73708.28 Maximum Ballast tank forward FP 98% 11932 299.949 14.604 0 0 Maximum Ballast Tank aft A.P. 98% 11517 4.8 11.172 0 0 Maximum

Total Weight= 165782 LCG=153.321 VCG=15.800 TCG=0.131 361861.4

FS corr.=2.183

VCG fluid=17.983

Equilibrium Result




Draft at FP m 9.772

Draft at AP m 9.108



WL Length m 305.201

WL Beam m 56.522





Block Coeff. 0.937





KB m 4.72

KG fluid m 17.983

BMt m 27.977

BML m 812.003



KMt m 32.697

KML m 816.723





Trim angle (+ve by stern) deg -0.1

Cargo Only Case (only cargo tanks filled)



Vertical Arm

Transverse Arm


Lightship 1 26000 152.6 15 0 0

Machinery 1 2542 24.6 10 0 0


m03 tpr1 1 193.1 62.72 36.306 0 0

m03 tpr2/1 1 226.4 77.4 36.488 0 0

m03 tpr2/2 1 226.4 93.3 36.488 0 0

m03 tpr3/1 1 226.4 109.2 36.488 0 0

m03 tpr3/2 1 226.4 125.1 36.488 0 0

m03 mpr1 1 539.5 143.421 42.368 0.021 0

m03 mpr2 1 829.2 166.051 46.522 -0.684 0

m03 mpr3 1 546.1 185.81 42.442 -0.022 0

m03 mpr4 1 542.8 207.06 42.532 -0.021 0


m03 tpr4/1 1 263.1 225.755 37.696 0.361 0

m03 tpr4/2 1 263.1 241.655 37.696 0.036 0

m03 tpr5 1 223.1 257.363 36.998 0.211 0

m33 1 2284 165.746 39.836 14.482 0

m31 1 5028 197.706 44.786 15.791 0

m34 1 1848 164.868 29.05 30.322 0

m51 1 2717 95.503 41.426 -16.738 0

m10 1 1858 120.175 37.3 -15.534 0

m06 1 1858 135.325 37.296 -15.534 0

m23 1 2174 194.568 39.996 -15.705 0

m13 1 1179 218.684 40.972 -14.399 0

m12 1 2031 164.859 39.076 -16.313 0

m42 1 2503 124.894 41.1 15.892 0

m01 1 126.7 275.722 59.653 10.106 0

Turret 1 2000 315.2 29 0 0




























Ballast bottom9.3 2% 23.31 248.075 0.025 -18.51 15551.87 Maximum Ballast bottom10.1 2% 22.79 272.35 0.025 18.51 15203.46 Maximum Ballast bottom10.2 2% 20.48 272.35 0.025 0 11026.58 Maximum Ballast bottom10.3 2% 22.79 272.35 0.025 -18.51 15203.46 Maximum













Ballast por7 2% 32.31 199.35 2.773 27.01 32.438 Maximum






Ballast port10 2% 31.91 272.35 2.773 27.01 32.037 Maximum Ballast starboard10 2% 31.91 272.35 2.773 -27.01 32.037 Maximum

Cargo 1.1 98% 9442 53.4 15.877 17.26 0 Maximum

Cargo 1.2 98% 9731 53.4 15.877 0 0 Maximum

Cargo 1.3 98% 9442 53.4 15.877 -17.26 0 Maximum

Cargo 2.1 98% 9327 77.85 15.877 17.26 0 Maximum

Cargo 2.2 98% 9612 77.85 15.877 0 0 Maximum

Cargo 2.3 98% 9327 77.85 15.877 -17.26 0 Maximum

Cargo 3.1 98% 9327 102.15 15.877 17.26 0 Maximum

Cargo 3.2 98% 9612 102.15 15.877 0 0 Maximum

Cargo 3.3 98% 9327 102.15 15.877 -17.26 0 Maximum

Cargo 4.1 98% 9327 126.45 15.877 17.26 0 Maximum

Cargo 4.2 98% 9612 126.45 15.877 0 0 Maximum

Cargo 4.3 98% 9327 126.45 15.877 -17.26 0 Maximum

Cargo5.1 98% 9327 150.75 15.877 17.26 0 Maximum

Cargo 5.2 98% 9612 150.75 15.877 0 0 Maximum

Cargo 5.3 98% 9327 150.75 15.877 -17.26 0 Maximum


Cargo6.1 98% 9327 175.05 15.877 17.26 0 Maximum

Cargo 6.2 98% 9612 175.05 15.877 0 0 Maximum

Cargo 6.3 98% 9327 175.05 15.877 -17.26 0 Maximum

Cargo7.1 98% 9327 199.35 15.877 17.26 0 Maximum

Cargo 7.2 98% 9612 199.35 15.877 0 0 Maximum

Cargo 7.3 98% 9327 199.35 15.877 -17.26 0 Maximum

Cargo8.1 98% 9327 223.65 15.877 17.26 0 Maximum

Cargo8.2 98% 9612 223.65 15.877 0 0 Maximum

Cargo 8.3 98% 9327 223.65 15.877 -17.26 0 Maximum

Cargo9.1 98% 9423 248.075 15.877 17.26 0 Maximum

Cargo 9.2 98% 9711 248.075 15.877 0 0 Maximum

Cargo 9.3 98% 9423 248.075 15.877 -17.26 0 Maximum

Cargo10.1 98% 9212 272.35 15.877 17.26 0 Maximum

Cargo 10.2 98% 9493 272.35 15.877 0 0 Maximum

Cargo 10.3 98% 9212 272.35 15.877 -17.26 0 Maximum

Slop tank1 2% 90.57 289.975 2.773 17.26 4205.221 Maximum

Slop tank2 2% 93.34 289.975 2.773 0 4603.036 Maximum

Slop tank3 2% 90.57 289.975 2.773 -17.26 4205.221 Maximum

Slop ballast 1.1 2% 10.68 289.975 0.025 18.51 7126.621 Maximum

Slop ballast 1.2 2% 9.598 289.975 0.025 0 5168.71 Maximum

Slop ballast 1.3 2% 10.68 289.975 0.025 -18.51 7126.621 Maximum

Slop ballast port 2% 14.96 289.975 2.773 27.01 15.018 Maximum Slop ballast starboard 2% 14.96 289.975 2.773 -27.01 15.018 Maximum ER ballast bottom1.1 2% 20.64 17.1 0.025 14.13 28922.45 Maximum ER ballast bottom1.2 2% 20.64 17.1 0.025 -14.13 28922.45 Maximum ER ballast bottom2.1 2% 22.71 32.85 0.025 14.13 31814.69 Maximum ER ballast bottom2.2 2% 22.71 32.85 0.025 -14.13 31814.69 Maximum

ER ballast port1 2% 19.94 17.1 2.773 27.01 20.023 Maximum ER ballast starboard1 2% 19.94 17.1 2.773 -27.01 20.023 Maximum

ER ballast port2 2% 21.94 32.85 2.773 27.01 22.026 Maximum ER ballast starboard2 2% 21.94 32.85 2.773 -27.01 22.026 Maximum

FW 2% 10.4 4.8 23.86 4.75 685.864 Maximum

FW 2% 10.4 4.8 23.86 -4.75 685.864 Maximum

Diesel tank 2% 172.8 13.45 2.773 0 73708.28 Maximum Ballast tank forward FP 2% 243.5 299.95 0.298 0 77878.98 Maximum Ballast Tank aft A.P. 2% 235 4.8 0.228 0 144435.5 Maximum

Total 345696 LCG=160.905 VCG=17.808 TCG=0.063 872013.5


Weight=

FS corr.=2.522

VCG fluid=20.331

Equilibrium Result




Draft at FP m 23.457

Draft at AP m 15.953



WL Length m 305.292

WL Beam m 56.533




Block Coeff. 0.82





KB m 9.957

KG fluid m 20.331

BMt m 13.428

BML m 389.823



KMt m 23.385

KML m 399.78


MTc tonne.m 4297.95



Trim angle (+ve by stern) deg -1.4


APPENDIX III WIND AND CURRENT LOADING:

Flow Forces and Center Multipliers:

Flow Angle FL/FLo FT/FTo (LCP-LCR)/(L/2-

LCR)

( deg)

0 1 0 _

10 1.087 0.174 0.5

20 1.321 0.342 0.5

30 1.5 0.5 0.5

40 1.4 0.643 0.451

50 1.125 0.766 0.415

60 0.75 0.866 0.325

70 0.375 0.94 0.225

80 0.1 0.985 0.133

90 0 1 0

100 -0.1 0.985 -0.133

110 -0.375 0.94 -0.225

120 -0.75 0.866 -0.325

130 -1.125 0.766 -0.415

140 -1.4 0.643 -0.451

150 -1.5 0.5 -0.5

160 -1.321 0.342 -0.5

170 -1.087 0.174 -0.5

180 -1 0 _

Table 3.1

3.1) Environmental Load Calculation: Case 1: Full Load Case (Draft=22m)

Longitudinal Wind Force

Sl. No.

Above Water Region H2 H1 L B

Wind Speed FLo

(m) (m) (m) (m) (m/s) (N)

1 main hull (full

load) 32.3 22.006 305.2 56.52 12 95497.445

2 m03tpr1 40.312 32.3 12.825 6.3 12 9314.6909


3 m03tpr2/1 40.676 40.312 15.4 6.3 12 442.28839

4 m03tpr2/2 - - - -

5 m03tpr3/1 - - - -

6 m03tpr3/2 - - - -

7 m03mpr1 52.436 43.092 20.7 6.26 12 12047.268

8 m03mpr2 - - - -

9 m03mpr3 52.584 52.436 20.7 6.26 12 198.26247

10 m03mpr4 52.764 52.584 20.7 6.26 12 241.43098

11 m03tpr4/1 43.092 41.696 15.9 6.26 12 1716.6608

12 m03tpr4/2 - - - -

13 m03tpr5 41.696 40.676 15.4 6.26 12 1239.8792

14 m33 47.372 32.3 27.775 21.38 12 61655.202

15 m31 57.272 49.9 30.3 23.6 12 37526.95

16 m51 50.552 47.692 29.6 22.9 12 13645.985

17 m10 42.3 32.3 14.6 23.845 12 44470.817

18 m06 - - - -

19 m12 45.852 42.3 28.975 23.025 12 16316.723

20 m42 49.9 47.372 33.65 21.38 12 11216.668

m42-m33 49.9 32.3 - 2.222 12 7573.4937

21 m23 47.692 45.852 26.975 23.025 12 8655.9114

22 m13 - - - -

23 m01 119.799 29.8 10.392 13.2 12 288257.13

24 Accommodation 44.8 29.8 20 20 12 55898.937

Net Force = 665915.74

Table 3.2


Transverse Wind Forces:

Sl. No.

Above Water Region H2 H1 L LCP (m)

Wind Speed FTo Moment LCR (m)

(m) (m) (m) (from

midship) (m/s) (N) (N-m) (from

midship)

1 main hull (full

load) 32.3 22.006 305.2 -1.074 12 515672.69 -

553832.47

2 m03tpr1 40.312 32.3 12.825 -89.88 12 18962.049 -1704309

3 m03tpr2/1 40.676 32.3 15.4 -75.2 12 23850.394 -

1793549.6

4 m03tpr2/2 40.676 32.3 15.9 -59.3 12 24624.757 -

1460248.1

5 m03tpr3/1 40.676 32.3 15.9 -43.4 12 24624.757 -

1068714.5

6 m03tpr3/2 40.676 32.3 15.4 -27.5 12 23850.394 -

655885.83

7 m03mpr1 52.436 32.3 20.7 -9.179 12 81671.876 -

749666.15

8 m03mpr2 52.584 32.3 20.7 13.451 12 82327.472 1107386.8

9 m03mpr2-m03mpr1 47.372 32.3 1.93 2.136 12 5565.6941 11888.323

10 m03mpr3 52.584 32.3 20.7 33.21 12 82327.472 2734095.3

11 m03mpr4 52.764 32.3 20.7 54.46 12 83125.814 4527031.8

12 m03tpr4/1 43.092 32.3 5.896 73.155 12 11915.92 871709.11

13 m03tpr4/2 43.092 32.3 15.4 89.055 12 31123.671 2771718.5

14 m03tpr5 41.696 32.3 15.4 104.763 12 26900.576 2818185

15 m33 - - -

16 m31 57.272 52.764 30.3 45.106 12 29778.785 1343201.9

17 m51 50.552 40.676 29.6 -57.097 12 59103.828 -

3374651.3

18 m10 - - -


19 m06 - - -

20 m12 - - -

21 m42 49.9 40.676 25.002 -27.706 12 46495.873 -

1288214.6

22 m23 - - -

23 m13 49.644 32.3 10.399 66.084 12 34886.473 2305437.7

24 m01 - - -

25 Accommodation 44.8 29.8 20 -

130.9005 12 55898.937 -

7317198.8

1262707.4 -

1475615.8 -

1.168613

Table 3.3


Wind Forces and Moments:

Wind Angle

Wind Speed FTo FLo

FL/FLo

FT/Fto FT FL

Resultant Force

Resultant Angle

(LCP-LCR)/(L/2-LCR) LCP

Moment About Midship

(deg) (m/s) (N) (N) (N) (N) (N) (Deg) LCR=-

1.168612564m (m) (N-m)

0 12 1 0 0 665915.74 665915.7377 0 _ _ _

10 12 1.087 0.174 219711.09 723850.41 756460.4259 16.88463468 0.5 71.512647 54096487.55

20 12 1.321 0.342 431845.94 879674.69 979958.4055 26.14707607 0.5 71.512647 70079419.72

30 12 1.5 0.5 631353.72 998873.61 1181675.081 32.29549959 0.5 71.512647 84504713.13

40 12 1.4 0.643 811920.88 932282.03 1236270.723 41.05238676 0.451 64.389884 79603328.14

50 12 1.125 0.766 967233.89 749155.2 1223427.531 52.24089041 0.415 59.156833 72374098.17

60 12 0.75 0.866 1093504.6 499436.8 1202160.35 65.45222605 0.325 46.074206 55388583.96

70 12 0.375 0.94 1186945 249718.4 1212929.379 78.11877488 0.225 31.537954 38253311.35

80 12 0.1 0.985 1243766.8 66591.574 1245548.208 86.93509308 0.133 18.164603 22624888.14

90 12 1262707 665916 0 1 1262707.4 0 1262707.431 90 0 -1.1686126 -1475615.769

100 12 -0.1 0.985 1243766.8 -

66591.574 1245548.208 -86.93509308 -0.133 -20.501828 -25536014.71

110 12 -0.375 0.94 1186945 -249718.4 1212929.379 -78.11877488 -0.225 -33.875179 -41088200.37

120 12 -0.75 0.866 1093504.6 -499436.8 1202160.35 -65.45222605 -0.325 -48.411431 -58198303.34

130 12 -1.125 0.766 967233.89 -749155.2 1223427.531 -52.24089041 -0.415 -61.494058 -75233523.74

140 12 -1.4 0.643 811920.88 -

932282.03 1236270.723 -41.05238676 -0.451 -66.727109 -82492771.14

150 12 -1.5 0.5 631353.72 -

998873.61 1181675.081 -32.29549959 -0.5 -73.849872 -87266553.83

160 12 -1.321 0.342 431845.94 -

879674.69 979958.4055 -26.14707607 -0.5 -73.849872 -72369803.13

170 12 -1.087 0.174 219711.09 -

723850.41 756460.4259 -16.88463468 -0.5 -73.849872 -55864505.87

180 12 -1 0 0 -

665915.74 665915.7377 0 _ _ _

1262707.431 at 90 -22600461.72

Table 3.4


Current Forces and Moments:

Current Angle

Current Speed FTo FLo FL/FLo FT/Fto FT FL

Resultant Force

Resultant Angle

(deg) (m/s) (N) (N) (N) (N) (N) (Deg)

0 1.31 1 0 0 96263.67 96263.665 0

10 1.31 1.087 0.174 513903.

2 104638.6 524448.0645 78.49084416

20 1.31 1.321 0.342 1010086 127164.3 1018058.848 82.82432897

30 1.31 1.5 0.5 1476733 144395.5 1483776.161 84.4151549

40 1.31 1.4 0.643 1899079 134769.1 1903855.171 85.94057969

50 1.31 1.125 0.766 2262356 108296.6 2264946.161 87.25919828

60 1.31 0.75 0.866 2557702 72197.75 2558721.089 88.38290143

70 1.31 0.375 0.94 2776259 36098.87 2776493.538 89.25483316

80 1.31 0.1 0.985 2909165 9626.367 2909180.792 89.81020012

90 1.31 2953466.9 96263.67 0 1 2953467 0 2953466.868 90

100 1.31 -0.1 0.985 2909165 -9626.37 2909180.792 -89.81020012

110 1.31 -0.375 0.94 2776259 -36098.9 2776493.538 -89.25483316

120 1.31 -0.75 0.866 2557702 -72197.7 2558721.089 -88.38290143

130 1.31 -1.125 0.766 2262356 -108297 2264946.161 -87.25919828

140 1.31 -1.4 0.643 1899079 -134769 1903855.171 -85.94057969

150 1.31 -1.5 0.5 1476733 -144395 1483776.161 -84.4151549

160 1.31 -1.321 0.342 1010086 -127164 1018058.848 -82.82432897

170 1.31 -1.087 0.174 513903.

2 -104639 524448.0645 -78.49084416

180 1.31 -1 0 0 -96263.7 96263.665 0

2953466.868 at 90

Table 3.5

Net Force (Wind + Current force):

Flow Angle

Wind Speed

Current Speed FT (Wind) FL(Wind)

FT (Current)

FL(Current)

FT (Wind + Current)

FL(Wind + Current)

Resultant Force

Resultant

Angle

(deg) (m/s) (m/s) (N) (N) (N) (N) (N) (N) (N) (deg.)

0 12 1.31 0 665915.7377 0 96263.665 0 762179.4027 762179.4027 0

10 12 1.31 219711.093 723850.4069 513903.235 104638.6039 733614.328 828489.0108 1106609.246 41.52

20 12 1.31 431845.9414 879674.6895 1010085.669 127164.3015 1441931.61 1006838.991 1758661.856 55.07

30 12 1.31 631353.7155 998873.6066 1476733.434 144395.4975 2108087.15 1143269.104 2398144.215 61.53

40 12 1.31 811920.8781 932282.0328 1899079.196 134769.131 2711000.074 1067051.164 2913437.761 68.52

50 12 1.31 967233.8921 749155.2049 2262355.621 108296.6231 3229589.513 857451.828 3341477.527 75.13


60 12 1.31 1093504.635 499436.8033 2557702.308 72197.74875 3651206.943 571634.5521 3695683.726 81.10

70 12 1.31 1186944.985 249718.4016 2776258.856 36098.87438 3963203.841 285817.276 3973496.722 85.87

80 12 1.31 1243766.82 66591.57377 2909164.865 9626.3665 4152931.685 76217.94027 4153631.033 88.95

90 12 1.31 1262707.431 0 2953466.868 0 4216174.299 0 4216174.299 90.00

100 12 1.31 1243766.82 -66591.5738 2909164.865 -9626.3665 4152931.685 -

76217.94027 4153631.033 -88.95

110 12 1.31 1186944.985 -249718.402 2776258.856 -

36098.87438 3963203.841 -285817.276 3973496.722 -85.87

120 12 1.31 1093504.635 -499436.803 2557702.308 -

72197.74875 3651206.943 -

571634.5521 3695683.726 -81.10

130 12 1.31 967233.8921 -749155.205 2262355.621 -

108296.6231 3229589.513 -857451.828 3341477.527 -75.13

140 12 1.31 811920.8781 -932282.033 1899079.196 -134769.131 2711000.074 -

1067051.164 2913437.761 -68.52

150 12 1.31 631353.7155 -998873.607 1476733.434 -

144395.4975 2108087.15 -

1143269.104 2398144.215 -61.53

160 12 1.31 431845.9414 -879674.69 1010085.669 -

127164.3015 1441931.61 -

1006838.991 1758661.856 -55.07

170 12 1.31 219711.093 -723850.407 513903.235 -

104638.6039 733614.328 -

828489.0108 1106609.246 -41.52

180 12 1.31 0 -665915.738 0 -96263.665 0 -

762179.4027 762179.4027 0.00

Max Force

(N) = 4216174.299 At 90

Table 3.6

Case 2: Ballast Load Case (Draft=7.895m)

Longitudinal Wind Forces:

Sl. No.

Above Water Region H2 H1 L B

Wind Speed FLo

(m) (m) (m) (m) (m/s) (N)

1 main hull (ballast

load) 32.3 8.985 305.2 56.52 12 191445.6368

2 m03tpr1 40.312 32.3 12.825 6.3 12 9314.690927

3 m03tpr2/1 40.676 40.312 15.4 6.3 12 442.2883914

4 m03tpr2/2 - - - -

5 m03tpr3/1 - - - -

6 m03tpr3/2 - - - -

7 m03mpr1 52.436 43.092 20.7 6.26 12 12047.26755

8 m03mpr2 - - - -

9 m03mpr3 52.584 52.436 20.7 6.26 12 198.2624682

10 m03mpr4 52.764 52.584 20.7 6.26 12 241.4309785

11 m03tpr4/1 43.092 41.696 15.9 6.26 12 1716.660789

12 m03tpr4/2 - - - -

13 m03tpr5 41.696 40.676 15.4 6.26 12 1239.8792

14 m33 47.372 32.3 27.775 21.38 12 61655.20207


15 m31 57.272 49.9 30.3 23.6 12 37526.9499

16 m51 50.552 47.692 29.6 22.9 12 13645.98514

17 m10 42.3 32.3 14.6 23.845 12 44470.81679

18 m06 - - - -

19 m12 45.852 42.3 28.975 23.025 12 16316.72287

20 m42 49.9 47.372 33.65 21.38 12 11216.66792

m42-m33 49.9 32.3 - 2.222 12 7573.493691

21 m23 47.692 45.852 26.975 23.025 12 8655.911423

22 m13 - - - -

23 m01 119.799 29.8 10.392 13.2 12 288257.1251

24 Accommodation 44.8 29.8 20 20 12 55898.93722

761863.9293 Table 3.7

Transverse Wind Forces:

Sl. No. Above Water Region H2 H1 L LCP (m) Wind Speed FTo Moment LCR (m)

(m) (m) (m) (from midship) (m/s) (N) (N-m) (from midship)

1 main hull (full load) 32.3 8.985 305.2 -1.074 12 1033779.3 -1110279

2 m03tpr1 40.312 32.3 12.825 -89.88 12 18962.049 -1704309

3 m03tpr2/1 40.676 32.3 15.4 -75.2 12 23850.394 -1793549.6

4 m03tpr2/2 40.676 32.3 15.9 -59.3 12 24624.757 -1460248.1

5 m03tpr3/1 40.676 32.3 15.9 -43.4 12 24624.757 -1068714.5

6 m03tpr3/2 40.676 32.3 15.4 -27.5 12 23850.394 -655885.83

7 m03mpr1 52.436 32.3 20.7 -9.179 12 81671.876 -749666.15

8 m03mpr2 52.584 32.3 20.7 13.451 12 82327.472 1107386.8

9 m03mpr2-m03mpr1 47.372 32.3 1.93 2.136 12 5565.6941 11888.323

10 m03mpr3 52.584 32.3 20.7 33.21 12 82327.472 2734095.3

11 m03mpr4 52.764 32.3 20.7 54.46 12 83125.814 4527031.8

12 m03tpr4/1 43.092 32.3 5.896 73.155 12 11915.92 871709.11

13 m03tpr4/2 43.092 32.3 15.4 89.055 12 31123.671 2771718.5

14 m03tpr5 41.696 32.3 15.4 104.763 12 26900.576 2818185

15 m33 - - -

16 m31 57.272 52.764 30.3 45.106 12 29778.785 1343201.9

17 m51 50.552 40.676 29.6 -57.097 12 59103.828 -3374651.3

18 m10 - - -


19 m06 - - -

20 m12 - - -

21 m42 49.9 40.676 25.002 -27.706 12 46495.873 -1288214.6

22 m23 - - -

23 m13 49.644 32.3 10.399 66.084 12 34886.473 2305437.7

24 m01 - - -

25 Accommodation 44.8 29.8 20 -130.9005 12 55898.937 -7317198.8

1780814.1 -2032062.3 -1.1410862

Table 3.8


Wind Forces and Moment:

Table 3.9


CURRENT FORCES AND MOMENTS

Current Angle Current Speed FTo FLo FL/FLo FT/Fto FT FL Resultant Force Resultant Angle

(deg) (m/s) (N) (N) (N) (N) (N) (Deg)

0 1.31 1 0 0 39304.233 39304.233 0

10 1.31 1.087 0.174 209825.53 42723.701 214130.9574 78.49084519

20 1.31 1.321 0.342 412415.69 51920.892 415671.1237 82.82432962

30 1.31 1.5 0.5 602946.92 58956.35 605822.4488 84.41515541

40 1.31 1.4 0.643 775389.74 55025.926 777339.7585 85.94058006

50 1.31 1.125 0.766 923714.68 44217.262 924772.3931 87.25919854

60 1.31 0.75 0.866 1044304.1 29478.175 1044720.031 88.38290157

70 1.31 0.375 0.94 1133540.2 14739.087 1133636.03 89.25483323

80 1.31 0.1 0.985 1187805.4 3930.4233 1187811.935 89.81020014

90 1.31 1205893.8 39304.23 0 1 1205893.8 0 1205893.84 90

100 1.31 -0.1 0.985 1187805.4 -3930.4233 1187811.935 -89.81020014

110 1.31 -0.375 0.94 1133540.2 -14739.087 1133636.03 -89.25483323

120 1.31 -0.75 0.866 1044304.1 -29478.175 1044720.031 -88.38290157

130 1.31 -1.125 0.766 923714.68 -44217.262 924772.3931 -87.25919854

140 1.31 -1.4 0.643 775389.74 -55025.926 777339.7585 -85.94058006

150 1.31 -1.5 0.5 602946.92 -58956.35 605822.4488 -84.41515541

160 1.31 -1.321 0.342 412415.69 -51920.892 415671.1237 -82.82432962

170 1.31 -1.087 0.174 209825.53 -42723.701 214130.9574 -78.49084519

180 1.31 -1 0 0 -39304.233 39304.233 0

1205893.84 at 90

Table 3.10

Net force (wind +current )

Flow Angl

e Wind Speed

Current Speed FT (Wind) FL(Wind)

FT (Current) FL(Current)

FT (Wind + Current)

FL(Wind + Current)

Resultant Force

Resultant Angle

(deg) (m/s) (m/s) (N) (N) (N) (N) (N) (N) (N) (deg.)

0 12 1.31 0 7.62E+05 0 39304.233 0 801168.1623 801168.1623 0

10 12 1.31 309861.6506 8.28E+05 209825.5282 42723.70127 519687.1788 870869.7924 1014144.447 30.83

20 12 1.31 609038.4167 1.01E+06 412415.6933 51920.89179 1021454.11 1058343.143 1470870.051 43.98

30 12 1.31 8.90E+05 1.14E+06 602946.92 58956.3495 1493353.962 1201752.244 1916850.153 51.18

40 12 1.31 1.15E+06 1.07E+06 775389.7391 55025.9262 1920453.195 1121635.427 2224006.858 59.71

50 12 1.31 1.36E+06 8.57E+05 923714.6814 44217.26213 2287818.269 901314.1826 2458959.066 68.50


60 12 1.31 1.54E+06 571397.947 1044304.065 29478.17475 2586489.062 600876.1218 2655367.73 76.92

70 12 1.31 1.67E+06 285698.9735 1133540.21 14739.08738 2807505.449 300438.0609 2823534.996 83.89

80 12 1.31 1.75E+06 76186.39293 1187805.432 3930.4233 2941907.305 80116.81623 2942998.011 88.44

90 12 1.31 1.78E+06 0 1205893.84 0 2986707.924 0 2986707.924 90.00

100 12 1.31 1.75E+06 -76186.39293 1187805.432 -3930.4233 2941907.305 -80116.81623 2942998.011 -88.44

110 12 1.31 1.67E+06 -285698.9735 1133540.21 -14739.08738 2807505.449 -300438.0609 2823534.996 -83.89

120 12 1.31 1.54E+06 -571397.947 1044304.065 -29478.17475 2586489.062 -600876.1218 2655367.73 -76.92

130 12 1.31 1.36E+06 -8.57E+05 923714.6814 -44217.26213 2287818.269 -901314.1826 2458959.066 -68.50

140 12 1.31 1.15E+06 -1.07E+06 775389.7391 -55025.9262 1920453.195 -1121635.427 2224006.858 -59.71

150 12 1.31 8.90E+05 -1.14E+06 602946.92 -58956.3495 1493353.962 -1201752.244 1916850.153 -51.18

160 12 1.31 609038.4167 -1.01E+06 412415.6933 -51920.89179 1021454.11 -1058343.143 1470870.051 -43.98

170 12 1.31 309861.6506 -8.28E+05 209825.5282 -42723.70127 519687.1788 -870869.7924 1014144.447 -30.83

180 12 1.31 0 -7.62E+05 0 -39304.233 0 -801168.1623 801168.1623 0.00

MAX FORCE

(N) = 2986707.924 At 90 °

Table 3.11

APPENDIX IV

4) STRENGTH AND STRUCTURAL DESIGN-GENERAL

1) Moment Calculation

a) The envelope hogging and sagging vertical wave bending moments were taken as:- Mwv-hog = fprob 0.19 fwv-v Cwv L

2BCb kNm Mwv-sag = -fprob 0.11 fwv-v Cwv L

2B (Cb+0.7) kNm Where fprob = 1.0 for scantling calculations; Distribution factor, fwv-v = 1.0 at amidships; Wave coefficient, Cwv = 10.75

L – Length between perpendiculars B – Breadth of ship Cb = Block coefficient

b) The envelope horizontal wave bending moment at amidships:-

Mh =fprob (0.3 + L/2000) fwv-hCwvL2TLCCb kNm

Where fprob = 1.0 for scantling calculations; Distribution factor, fwv-h = 1.0 at amidships; Wave coefficient, Cwv = 10.75

TLC – Draught in loading condition being considered L – Length between perpendiculars B – Breadth of ship


Cb = Block coefficient

2) Load Calculation: In this section the significance of the all the load components, taken into consideration while calculating the scantlings of the ship, is mentioned. The formula used in calculating the load components are also mentioned as in ABS rules (Section 7/2.2)

a) Phys - Static sea pressure Phys = swg (TLC " z) kN/m2

Where: z = vertical coordinate of load point, in m, and is not to be greater than TLC sw = density of sea water, 1.025tonnes/m3 TLC = draught in the loading condition being considered, in m g = acceleration due to gravity, 9.81m/s2

Fig 4.1

b) Pin-tk - Static tank pressure Pin"tk = gZtk kN/m2

Where: Ztk = vertical distance from highest point of tank, excluding small hatchways, to the load

point

c) Pin-air - Static tank pressure in the case of overfilling or filling during flow through ballast water exchange

Pin"air = sw gZair kN/m2


Where: Zair = vertical distance from top of air pipe or overflow pipe to the load point, whichever is the lesser, sees Figure 7.2.3, in m = Ztk + hair hair = height of air pipe or overflow pipe, in m, is not to be taken less than 0.76 above highest point of tank, excluding small hatchways. For tanks with tank top below the weather deck the height of air-pipe is not to be taken less than 0.76m above deck at side unless the tanks are arranged with overflow tank

Fig 4.2

d) Pin" flood - The pressure in compartments and tanks in a flooded or damaged condition. Pin" flood = sw gZflood kN/m2

Where: Zflood = vertical distance from the load point to the deepest equilibrium waterline in damaged condition obtained from applicable damage stability calculations or to freeboard deck if the damage waterline is not given, in m

e) Pin-test - The tank testing pressure is to be taken as the greater of the following:-

Pin-test = sw gZtest kN/m2 Pin-test = sw gZtk + Pvalve kN/m2

Where: Ztest = vertical distance to the load point, is to be taken as the greater of the following (a) Top of overflow (b) 2.4 m above top of tank Ztk = vertical distance from highest point of tank, excluding small hatchways, to the load point, see above figure Pvalve = setting of pressure relief valve, if fitted, is not to be taken less than 25 kN/m2


f) Pstat - The pressure on decks and inner bottom:- Pstat = Pdeck kN/m2

Where: Pdeck = uniformly distributed pressure on lower decks and decks within superstructures, in kN/m2. Pdeck is not to be taken less than 16 kN/m2.

g) Fstat - The load acting on supporting structures and securing systems for heavy units of

cargo, equipment or structural components, is to be taken as: Fstat = mung kN Where:

mun = mass of unit not less than 20 tonnes

h) Pdrop - The added overpressure due to sustained liquid flow through air pipe or overflow pipe in the case of overfilling or filling during flow through ballast water exchange, is to be taken as 25 kN/m2.

i) Pin-dyn - The simultaneously acting dynamic tank pressure, for tanks in the cargo region,

is to be taken as: Pin-dyn = f (fvPin-v + ftPin-t + flngPin-lng) kN/m2

Where: Pin-v = envelope dynamic tank pressure due to vertical acceleration as defined in ABS rules for double hull tankers (Section7/3.5.4.1)

Pin-t = envelope dynamic tank pressure due to transverse acceleration as defined in ABS rules for double hull tankers (Section7/3.5.4.2)

Pin-lng = envelope dynamic tank pressure due to longitudinal acceleration as defined in ABS rules for double hull tankers (Section7/3.5.4.3)

fv = dynamic load combination factor for vertical acceleration for considered dynamic load case. ft = dynamic load combination factor for transverse acceleration for considered dynamic load case. flng = dynamic load combination factor for longitudinal acceleration for considered dynamic load case.

For all the factors given above i.e. fv, ft, flng refer ABS rules Section7/6.3.1.2).

f heading correction factor, as given below:- f = 0.8 for beam sea dynamic load cases = 1.0 for all other dynamic load cases For tanks outside the cargo region, Pin-dyn = f (fvPin-v + |ftPin-t|+ |flngPin-lng|) kN/m2

j) Pwv-dyn - The simultaneously acting dynamic wave pressure, for the port and starboard

side within the cargo tank region for a considered dynamic load case is to be taken as


follows, but not to be less than – swg(TLC – z) below still waterline or less than 0 above still waterline:

Pwv-dyn = Pctr + |y| (Pbilge- Pctr)/0.5Blocal between centerline and start of bilge

Pwv-dyn = Pbilge + z (PWL-Pbilge)/TLC between end of bilge and still waterline Pwv-dyn = PWL – 10 (z- TLC) for side-shell above still waterline

Where:

Pctr = dynamic wave pressure at bottom centerline, to be taken as, fctrPex-max kN/m2

Pbilge = dynamic wave pressure at z = 0 and y = Blocal/2, to be taken as fbilgePex-max kN/m2.

PWL dynamic wave pressure at waterline, to be taken as fWLPex-max kN/m2

Pex-max = envelope maximum dynamic wave pressure, in kN/m2, as defined in ABS rules (Section7/3.5.2.2).

fWL = dynamic load combination factor for dynamic wave pressure at still waterline for considered dynamic load case. fbilge = dynamic load combination factor for dynamic wave pressure at bilge for considered dynamic load case fctr = dynamic load combination factor for dynamic wave pressure at centerline for considered dynamic load case. Blocal = local breadth at waterline for considered draught, in m TLC = draught in the loading condition being considered, in m


3) Scantling Calculation: Minimum Net Thickness for Plating and Local Support Members

Table 4.1

Minimum Net Thickness for Primary Support Members

Table 4.2


Thickness Requirements for Plating

Table 4.3


Section Modulus Requirements for Stiffeners

Table 4.4


Design Load Set for Plating and Local Support Members


Table 4.5

Specifications of Load Combinations and other Parameters for each Load Set


Table 4.6

Design Load Combination

Table 4.7


Material Classes or Grade of Structural Members

Table 4.8


Materials Grade

Table 4.9


Corrosion Addition

Fig 4.1


4) Moment curves:

a) Scantling Case

Hogging Case:

Graph 4.1 Sagging Case:

Graph 4.2

-2000

-1500

-1000

-500

0

500

1000

1500

2000

-50 0 50 100 150 200 250 300 350-40

-30

-20

-10

0

10

20

30

40

-2500

-2000

-1500

-1000

-500

0

500

1000

1500

2000

2500

Buoyancy

Weight

Net Load

Shear

Moment

Moment = Long. Pos. = -2328.639 tonne.mx10^3 137.774 m

Long. Pos. m

Load t/m

Shear tx10^3

Mom

ent

tonne.m

x10

3̂

-2000

-1500

-1000

-500

0

500

1000

1500

2000

-50 0 50 100 150 200 250 300 350-20

-15

-10

-5

0

5

10

15

20

-750

-500

-250

0

250

500

750

Buoyancy

Weight

Net LoadShear

Moment


Long. Pos. m

Load t

/m

Shear tx1

03̂

Mom

ent

tonne.m

x10

3̂


b) Cargo only

Sagging:

Graph 4.3 Hogging:

Graph 4.4

-2000

-1500

-1000

-500

0

500

1000

1500

2000

-50 0 50 100 150 200 250 300 350-10

-7.5

-5

-2.5

0

2.5

5

7.5

10

-600

-400

-200

0

200

400

600

Buoyancy

Weight

Net Load

Shear

Moment


Long. Pos. m

Lo

ad

t/m

Sh

ea

r tx1

0^3

Mo

me

nt to

nn

e.m

x1

0^3

-2000

-1500

-1000

-500

0

500

1000

1500

2000

-50 0 50 100 150 200 250 300 350-25

-20

-15

-10

-5

0

5

10

15

20

25

-2500

-2000

-1500

-1000

-500

0

500

1000

1500

2000

2500

Buoyancy

Weight

Net Load

Shear

Moment


Long. Pos. m

Load t/m

Shear tx10^3

Mom

ent tonne.m

x10

3̂


c) Ballast Only

Sagging:

Graph 4.5 Hogging:

Graph 4.6

-2000

-1500

-1000

-500

0

500

1000

1500

2000

-50 0 50 100 150 200 250 300 350-12

-8

-4

0

4

8

12

-600

-400

-200

0

200

400

600

Buoyancy

Weight

Net Load

Shear

Moment


Long. Pos. m

Load t/m

Shear tx10

3̂

Mom

ent tonne.m

x10

3̂

-2000

-1500

-1000

-500

0

500

1000

1500

2000

-50 0 50 100 150 200 250 300 350-15

-10

-5

0

5

10

15

-1200

-800

-400

0

400

800

1200

Buoyancy

Weight

Net Load

Shear

Moment

Moment = Long. Pos. = 1173.655 tonne.mx10^3 145.238 m

Long. Pos. m

Lo

ad

t/m

Sh

ea

r tx1

0^3

Mo

me

nt to

nn

e.m

x1

0^3


5) MATLAB Codes:


Appendix V 5.1 Mooring Line Materials

a) Chain:

Fig A5.1: Stud Chain Link Weight and Stiffness: Weight and stiffness properties of chain are independent of grade. Typically, for a mooring analysis, submerged weight per unit length (w) and axial stiffness (AE) of chain are necessary. The following equations provide these for any stud chain diameter, D:

…… eq. 1

…… eq. 2

Breaking Strength: Breaking strength of a chain is a very important and highly uncertain parameter. As chain is a series, it is only as strong as its weakest link. The breaking strength quoted by the manufacturers is the catalogue break strength (CBS) whilst the chain is only tested up to the proof load. …… eq. 3 The factor ‘c’ is selected according to material grade and whether the CBS or proof load is required.

Grade (specification) Catalogue Break Strength Proof Load ORQ (Oil Rig Quality) 21.1 14.0

3 22.3 14.8 3S 24.9 18.0 4 27.4 21.6

Table 5.1: Values of factor ‘c’

Drag and Inertia Coefficient: The drag and inertia coefficient apply to the nominal projected area and volume respectively of a circular cylinder with the given nominal chain diameter.

Reference Drag Coefficient Inertia Coefficient Huse (1992) 2.6 -

Larsen and Sandvik (1990) 3.0 2.0 Table 5.2: Drag and Inertia coefficients


b) Wire Rope:

Fig A5.2: Six Stranded Wire Rope (IWRC)

Weight and Stiffness: The weight and stiffness of wire ropes vary depending not only on rope construction but also on the manufacturer. Thus it is always necessary to establish these properties specifically for the ropes in question. However, the following table gives generic equations which may be used to compute these properties, as a first esticonstruction types based on the nominal diameter of the rope, d.

Construction

Six strand (IWRC)

Spiral strand

Table 5.3: Wire rope weight and stiffness properties

Breaking Strength: The breaking strength is dependent upon the construction of rope as well as the grade of steel used.

Construction

Six strand (IWRC)

Six strand (IWRC)

Spiral strand

Table 5.4: Nominal breaking strength of steel wire mooring ropes Drag and Inertia Coefficients: The following

Reference Huse (1992)

Larsen and Sandvik (1990)DNV (1996)

Table 5.5: Wire drag and inertia coefficients

: Six Stranded Wire Rope (IWRC) Fig A5.3: Spiral Stranded Wire Rope

Weight and Stiffness: The weight and stiffness of wire ropes vary depending not only on rope construction but also on the manufacturer. Thus it is always necessary to establish these properties specifically for the ropes in question. However, the following table gives generic equations which may be used to compute these properties, as a first estimate, for the different construction types based on the nominal diameter of the rope, d.

Submerged weight/ length, w Stiffness/ length,

0.034 N (d in mm) 45000

0.043 N (d in mm) 90000Table 5.3: Wire rope weight and stiffness properties

Breaking Strength: The breaking strength is dependent upon the construction of rope as well as

Ultimate Tensile Stress (N/mm2) Breaking S

1770 525 1860 600 1570 900

Table 5.4: Nominal breaking strength of steel wire mooring ropes

Drag and Inertia Coefficients: The following table summarizes the drag and inertia coeff.

Drag Coefficient Inertia Coefficient1.8

Larsen and Sandvik (1990) 1.5 1.8

Table 5.5: Wire drag and inertia coefficients

: Spiral Stranded Wire Rope

Weight and Stiffness: The weight and stiffness of wire ropes vary depending not only on rope construction but also on the manufacturer. Thus it is always necessary to establish these properties specifically for the ropes in question. However, the following table gives generic

mate, for the different

Stiffness/ length, AE

N (d in mm)

N (d in mm)

Breaking Strength: The breaking strength is dependent upon the construction of rope as well as

Breaking Strength (N)

(d in mm)

(d in mm)

(d in mm) Table 5.4: Nominal breaking strength of steel wire mooring ropes

table summarizes the drag and inertia coeff.

Inertia Coefficient -

2.0 -


c) Properties of Typical Systems: The purpose of a mooring system is to maintain the moored vessel on station with as little an excursion as possible. Clearly some station keeping tolerance should be achieved which trades off excursion for reduced line tension and hence reduced mooring size and cost. The following tables present typical excursions and natural periods for a range of typical mooring systems.

Water Depth (m) Mooring Type Semi-submersible Ship

30 Chain/Wire 30-45% 40-55% 150 Chain 15-25% 30-40% 500 Chain/Wire 25-30% 20-30%

1000 Fibre ropes 5-10% 5-15% Table 5.6: Extreme excursions as a percentage of water depth

Water Depth (m) Mooring Type Semi-submersible Ship

30 Chain/Wire 30 45 150 Chain 60-120 60-150 500 Chain/Wire 120-180 150-250

1000 Fibre ropes 90-110 120-150 Table 5.7: Typical natural period of mooring systems

d) Guidance, Rules and Regulations: For drilling rigs, the International Association of Classification Societies (IACS) has agreed on the safety factors on line tensions for survival performance but associated calculation methodology to arrive at the characteristics tensions is still not uniquely defined. Typically, when quasi-static analysis methodology is used (i.e. line dynamics is ignored) in survival conditions, safety factors on line tensions which are commonly applied come from IACS as presented below. Condition Safety factor (=Break strength/ Max. Tension)

Intact 1.8 One line removed 1.25 Transient 1.1

Table 5.8: IACS safety factors


2) Graphs from “Floating structures: a guide for design and analysis”

Fig 5.4: Geometric horizontal force-deflection characteristics

Fig 5.5: Horizontal tangent stiffness Fig 5.6: Geometric vertical force-horizontal def. (excluding elastic effects) characteristics of a 6 catenary SPM


Fig 5.7: Effect of elastic flexibility

Fig 5.8: Maximum chain length to Fig 5.9: Max and Min line tensions Touch down point


5.2 Dynamic Contribution to the mooring line tension:

In order to get a better understanding of the dynamics and to provide simple tools for preliminary assessment of the feasibility of mooring systems, Polderijk (1985) derived approximate analytic solutions and provided a number of checks for their applicability. Check 1:

Drag-inertia parameter =

>>1

Where a is amplitude of oscillation, Ca is added mass coefficient and m and are mooring line mass per unit length and density respectively. If this check is satisfied then the effects of line inertia can be neglected. Check 2:

Where L is the suspended length, T is the line tension at the top, is the damping coefficient and is the frequency of motion in radians per sec. Depending upon the outcome of check 2, the dynamic tension can be calculated from either of following 2 expressions:

Quasi-static:

Where:

Damping Dominated Dynamics:

Where:

5.3 Mooring Calculations: Mooring line configuration: 6!2 legs Environmental Load, H= 5.186 MN The maximum excursion of system= 15% of water depth Case 1: Only chain (R3S)

Determination of diameter: From Appendix III,1


=24.9 (for R3S chain) Suppose D=100mm

The design strength (the mean load) =

Thus this diameter is acceptable. Suppose D=90mm


Thus this diameter is NOT acceptable. Suppose D=95mm


Thus this diameter is acceptable. Suppose D=92mm


Thus this diameter is NOT acceptable. So, the minimum acceptable diameter is D=95 mm. Choose To/wh: For each pair of chains: Using eq. 1


From figure: 9.48

Dynamic Contribution to Tension: From Appendix 5; N Thus, net tension T= To+

Total Line Length: From figure 9.53; L=1593.75m

The maximum line tension is;

Safety Factor:

So the mooring line is acceptable. Case 2: Chain-Wire rope-Chain (depth wise 100m-650m-100m) Mooring line configuration: 6!2 legs Environmental Load, H= 5.186 MN The maximum excursion of system= 30% for chain and 20% for wire rope.

Determination of diameter: From Appendix 1;

Suppose D=100mm


Thus this diameter is NOT acceptable. Suppose D=200mm


Thus this diameter is more than required.


Suppose D=125mm


Thus this diameter is ACCEPTABLE. Choose To/wh: For each pair of ropes:

Also, for the chain of Diameter =95mm

From figure: 9.48

Dynamic Contribution to Tension: From Appendix 5; N Thus, net tension = To+

Thus, net tension = To+

Total Line Length: From figure 9.53; L|rope=2080m L|chain=500m

Equivalent Stiffness K=

Where; Y=young’s modulus; A=cross section area ; L=total length Equivalent Stiffness of combination of Chain and wire rope;


Thus Net tension in the combination =2.58 MN For this tension value the Factor of safety for both the conditions, intact and damage, are within the limits stated by IACS. Thus, the mooring line is acceptable. Case 3: Chain-Wire rope-Chain (depth wise 100m-500m-250m) Mooring line configuration: 6!2 legs Environmental Load, H= 5.186 MN The maximum excursion of system= 30% for chain and 20% for wire rope.

The friction in the grounded length is frequently ignored in static calculations but its inclusion simply reduces the horizontal load as one progress from the touchdown point to the anchor. Thus the anchor load is lower than H, the constant horizontal component of the line tension in the water column. This tension variation is given by; ;

Where the grounded length from the touchdown is point and is the coeff. of friction,

commonly taken to be 1 and 0.6 for chain and wire rope respectively. Thus,

Determination of diameter: From Appendix 1;

Suppose D=95mm


Thus this diameter is ACCEPTABLE. Choose To/wh: For each pair of ropes:

Also, for the chain of Diameter =80mm For each pair of chain:


From figure: 9.48

Dynamic Contribution to Tension: From Appendix 5;



Total Line Length: From figure 9.53; L|rope=2000m L|chain=1094m

Equivalent Stiffness K=

Where; Y=young’s modulus; A=cross section area ; L=total length Equivalent Stiffness of combination of Chain and wire rope;

Thus Net tension in the combination =1.392 MN For this tension value the Factor of safety for both the conditions, intact and damage, are within the limits stated by IACS. Thus, the mooring line is Acceptable. Moreover, this combination gives the least working tension and least weight of mooring line for same environmental load. Thus this combination is accepted over the other two.


APPENDIX VI LIST OF UNITS CONSUMING POWER

TO

PS

IDE

S

YS

TE

M

DE

SC

RIP

TIO

N

DESCRIPTION

QU

AN

TIT

Y

RA

TE

D P

OW

ER

(KW

)

1 CHEMICAL INJECTION SYSTEM

Oil Corrosion Inhibitor Injection Pump (Wellhead)

1 2.2


Oil Corrosion Inhibitor Injection Pump (Wellhead)

1 2.2


Oil Corrosion Inhibitor Injection Pump (Topsides)

1 x 100% cont. Service

2.2



1 x 100% stand-by

2.2



1 2.2


Scale Inhibitor Injection Pump (Topside) 1 x 100% cont. Service

2.2


Scale Inhibitor Injection Pump (Downhole) 1 x 100% cont. Service

2.2


Scale Inhibitor Injection Pump (Topside & Downhole)

1 x 100% stand-by

2.2


Wax Inhibitor Injection Pump (Wellhead) 1 x 100% cont. Service

25


Wax Inhibitor Injection Pump ((Wellhead) 1 x 100% stand-by

25


Wax Inhibitor Injection Pump (Downhole) 25


Demulsifier Injection Pump (Topside) 1 x 100% cont. Service

2.2


Demulsifier Injection Pump (Topside) 1 x 100% stand-by

2.2


Demulsifier Injection Pump (Downhole) 2.2


Demulsifier Injection Pump (Wellhead) 1 x 100% cont. Service

5.5


Demulsifier Injection Pump (Wellhead) 1 x 100% stand-by

5.5


Asphaltene Inhibitor Injection Pump (Topside)


2.2


Asphaltene Inhibitor Injection Pump (Downhole)


2.2



Asphaltene Inhibitor Injection Pump (Topside & Downhole)

1 x 100% stand-by

2.2


Down Hole Chemical Inhibitors Injection Pump


2.2


Down Hole Chemical Inhibitors Injection Pump

1 x 100% stand-by

2.2


Methanol Injection Pump (Topside) 1 x 100% cont. Service

280


Methanol Injection Pump (Topside) 1 x 100% stand-by

280


Methanol Injection Pump (Wellhead) 1 x 100% cont. Service

280


Methanol Injection Pump (Wellhead) 1 x 100% cont. Service

280


Methanol Injection Pump (Wellhead) 1 x 100% Disc. Cont. Service

280


Polyelectrolite Injection Pump (Produced Water) (Topside)


2.2


Polyelectrolite Injection Pump (Produced Water) (Topside)

1 x 100% stand-by

2.2


Defoamer Injection Pump (Topsides) 1 x 100% cont. Service

2.2


Defoamer Injectioon Pump (Topsides) 1 x 100% stand-by

2.2


Chemical Transfer Pump 1 x 100% 20

32 MANIFOLD SYSTEM H.P Pump HP1 1 1310

33 MANIFOLD SYSTEM H.P Pump HP2 1 1310

34 MANIFOLD SYSTEM L.P Pumps LP1 1 762

35 MANIFOLD SYSTEM L.P Pumps LP2 1 762

36 MANIFOLD SYSTEM Return Reservoir Pump, HP3 1 20

37 SEPARATION SYSTEM Slurry Pump 1 x 100 % 45

38 SEPARATION SYSTEM Dehydrator feeding Pump 1 x 100 % Cont. Service

270

39 SEPARATION SYSTEM Dehydrator feeding Pump 1 x 100 % Stand-by

270

40 CRUDE OIL TREATMENT

Oil Dehydrator 1 x 100 % Cont. Service

750


Oil Desalter 1 x 100 % Cont. Service

750


Produced Water Recycle Pump A 1 x 100 % Cont. Service

330


Produced Water Recycle Pump B 1 x 100 % Stand-by

330



Treated Oil Pump A 1 x 100 % Cont. Service

270


Treated Oil Pump B 1 x 100 % Stand-by

270

46 FLARE SYSTEM HP Flare KO-Drum pump A 1 x 100% interm. Service

30

47 FLARE SYSTEM HP Flare KO-Drum pump B 1 x 100% stand-by

30

48 FLARE SYSTEM LP Flare KO-Drum pump A 1 x 100% interm. Service

22

49 FLARE SYSTEM LP Flare KO-Drum pump B 1 x 100% stand-by

22

50 GAS COMPRESSION SYSTEM - 1st TRAIN

Gas Compression Package (1st train) 1 x 50 % Cont service

5800

51 GAS COMPRESSION SYSTEM - 2nd TRAIN

Gas Compression Package (2nd train) 1 x 50 % Cont service

5800

52 GAS COMPRESSION SYSTEM - 3rd TRAIN

Gas Compression Package (3rdt train) 1 x 50 % Stand-by

5800

53 GAS COMPRESSION SYSTEM

Pre Lube Pump 1 8

54 GAS DEHYDRATION SYSTEM

Glycol Transfer Pump 1 x 100 % Discontinous Service

8


Glycol circulation Pump 1 x 100 % Cont. Service

16


Glycol circulation Pump 1 x 100 % Stand-by

16


Antifoam and pH Controller Dosing Pump 1 x100 % Cont. Service

1

58 COOLING MEDIUM SYSTEM

Cooling Medium Pump A 1 x 100 % Cont service

210

59 COOLING MEDIUM SYSTEM

Cooling Medium Pump B 1 x 100 % Stand-by

210

60 HEATING MEDIUM SYSTEM

Heating Medium Pump A 1 x 100 % Cont. Service

240

61 HEATING MEDIUM SYSTEM

Heating Medium Pump B 1 x 100 % Stand-by

240

62 SEA WATER SYSTEM Sea Water Coarse filter A 1 x 100 % Cont. Service

2.2

63 SEA WATER SYSTEM Sea Water Coarse filter B 1 x 100% stand-by

2.2

64 HULL Sea Water Lift Pump 1 x 100 % Cont. Service

1200

65 HULL Sea Water Lift Pump 1 x 100 % Stand-by

1200

66 HULL Oil Circulation Pump 1 100


67 HULL Oil Pressure Pump 1 100

68 WATER INJECTION SYSTEM

Air Scour Blower "A" 1 x 33 % Cont. Service

60


Air Scour Blower "B" 1 x 100 % Stand-by

60


Sulphate Removal Pump "A" 1 x 50 % Cont. Service

1700


Sulphate Removal Pump "B" 1 x 50 % Cont. Service

1700


Sulphate Removal Pump "C" 1 x 50 % Cont. Service

1700


Vacuum Pump 1 x 100 % Cont. Service

80


Vacuum Pump 1 x 100 % Cont. Service

80


Water Injection Pump A 1 x 50 % Cont. Service

12200


Water Injection Pump B 1 x 50 % Cont. Service

12200


Water Injection Pump C 1 x 50 % Cont. Service

12200


Non Oxydizing Biocide dosing pump 1 x 100% 3


Non Oxydizing Biocide dosing pump 1 x 100% 3

80 FRESH WATER GENERATION SYSTEM

FW maker HP Pump "A" 1 x 100 % Cont. Service

300


FW maker HP Pump "B" 1 x 100 % Stand-by Service

300


Fresh water Pump A 1 x 100 % Cont. Service

60


Fresh water Pump B 1 x 100 % Stand-by Service

60

84 PRODUCED WATER SYSTEM

Flotation unit Pump 1 x 100 % Cont. Service

100


Flotation unit Pump 1 x 100 % Stand-by

100


Produced Water Booster Pump 1 x 100 % Cont. Service

100


Gas Dehydration Package 1 x 100 % Cont. Service

350


Reflux condenser 1 x 100 % 10



Glycol Reboiler ** 1 x 100 % 200


Rich / Lean Glycol Exchanger 1 x 100% 200


Glycol cooler 1 x 100% 60

Table 6.1

LIST OF POWER REQUIREMENTS OF VARIOUS FPSO SYSTEMS

PROCESSING PLANT

Flow Rate Head Total Qty

Contd.Qty Rated Shaft Power

Motor Eff.

Power of each unit

m3/h m Kw Kw

Small Sized Pump 22 15 2.2 0.788 2.791878173

Wax Inhibitor Injection Pump

3 2 25 0.885 28.24858757

Demulsifier Injection Pump

2 1 5.5 0.84 6.547619048

Methanol Injection Pump

500 120 5 4 280 0.924 303.030303

Chemical Transfer Pump

1 1 20 0.885 22.59887006

H.P Pump HP1(Manifold)

1987.5(300,000BPD) 325 2 2 1310 0.924 1417.748918

L.P Pumps LP1(Processing)

1325 140 2 2 762 0.924 824.6753247

Return Reservoir Pump

1 1 20 0.885 22.59887006

Slurry Pump 1 1 45 0.885 50.84745763

Dehydrator feeding Pump

500 120 2 1 270 0.924 292.2077922

Oil Dehydrator Extrapolated N.A. 1 1 750 0.924 811.6883117

Oil Desalter Extrapolated N.A. 1 1 750 0.924 811.6883117

Produced Water Recycle Pump

1192.5(180,000BPD) 70 2 1 330 0.924 357.1428571

HP Flare Pump 2 1 30 0.885 33.89830508

LP Flare Pump 1325(200,000BPD) 50 2 1 22 0.885 24.85875706

Treated Oil Pump 2 1 270 0.924 292.2077922

Gas Compressors Extrapolated N.A. 3 2 5800 0.924 6277.056277

Lube & Glycol Transfer pump

2 2 8 0.84 9.523809524

Glycol circulation Pump

2 1 16 0.855 18.71345029

Cooling Medium Pump

720 70 2 1 210 0.924 227.2727273

Heating Medium Pump

720 80 2 1 240 0.924 259.7402597

Oil Circulation Pump 350 70 2 2 100 0.924 108.2251082

Air Scour Blower 2 1 60 0.902 66.51884701


Sulphate Removal Pump

2650 (400,000BPD) 140 3 3 1700 0.924 1839.82684

Vacuum Pump 2 2 80 0.917 87.24100327

Water Injection Pump

860 1550 3 3 6100 0.924 6601.731602

Non Oxydizing Biocide dosing pump

Extrapolated N.A. 2 2 3 0.788 3.807106599

FW maker HP Pump 220 300 2 1 300 0.924 324.6753247

Fresh water Pump 100 130 2 1 60 0.902 66.51884701

Produced Water Booster Pump

100 210 1 1 100 0.924 108.2251082

Gas Dehydration Package

Extrapolated N.A. 1 1 350 0.924 378.7878788

Reflux condenser Extrapolated N.A. 1 1 10 0.84 11.9047619

Glycol Reboiler Extrapolated N.A. 1 1 200 0.924 216.4502165

Rich / Lean Glycol Exchanger

Extrapolated N.A. 1 1 200 0.924 216.4502165

Glycol cooler Extrapolated N.A. 1 1 60 0.902 66.51884701

Table6.2

BALLAST WATER

CONTROL

Total Qty

Contd.Qty Rated Shaft Power

Motor Eff.

Power of each unit

Ballast Water Pump 3228(total) 60 4 3 300 0.924 974.025974

OFFLOADING CRUDE

CONTROL

Total Qty

Contd.Qty Rated Power

Motor Eff.

Unit Power

Crude Offloading Pumps

6625(total) 200 30 6 910 0.924 984.8484848

Tank Cleaning Pump 300 120 1 1 163.5 0.924 176.9480519

Portable Unloading Standby Pump

1105 200 1 0 910 0.924 0

ACCOMODATION Total Qty


Motor Eff.

Power of each unit

Power assuming 1.5Kw per person

N.A. N.A. 210

Electronic System N.A. N.A. Total Qty


Demand factor

Power of each unit

Main control Console

N.A. N.A. 1 1.5 0.6 0.9

Engine Room Panel N.A. N.A. 1 3 1 3

Compass N.A. N.A. 1.2 0.5 0.6

Interior Communications

N.A. N.A. 2.3 0.2 0.46

Radio N.A. N.A. 4.6 0.4 1.84

Battery Charger N.A. N.A. 3.5 0.2 0.7

Alarm N.A. N.A. 0.1 1 0.1

Smoke/Gas detactors N.A. N.A. 5 1 5


Other System Total Qty


Demand factor

Power of each unit

Sewage Grinder 1 2.1 1 2.1

Life Boat Winch(each winch

7men)

20(each 12.7)

254 0.1 25.4

Refrigeration compressor

N.A. N.A. 1 231 0.1 23.1

Potable water Pump 10 1 10

Main Bilge, Fire, G.S. Pumps

500 200 3 460 0.1 150

Work Shop N.A. N.A. 16.3 0.1 1.63

Sewage Blower 1.4 1 1.4

Helideck N.A. N.A. 1 1 1

Table 6.3

Extrapolated: The values have been extrapolated from original FPSO

LOAD CASE 1:ONLY PROCESSING PLANT WORKING ( UNLIKELY CASE)

PROCESSING PLANT Total Qty

Unit Power Unit in Use Load Factor Power

Kw

Small Sized Pump 22 2.791878173 15 1 41.87817259

Wax Inhibitor Injection Pump 3 28.24858757 2 1 56.49717514

Demulsifier Injection Pump 2 6.547619048 1 1 6.547619048

Methanol Injection Pump 5 303.030303 4 1 1212.121212

Chemical Transfer Pump 1 22.59887006 1 1 22.59887006

H.P Pump HP1(Manifold) 2 1417.748918 2 1 2835.497835

L.P Pumps LP1(Processing) 2 824.6753247 2 1 1649.350649

Return Reservoir Pump 1 22.59887006 1 1 22.59887006

Slurry Pump 1 50.84745763 1 1 50.84745763

Dehydrator feeding Pump 2 292.2077922 1 1 292.2077922

Oil Dehydrator 1 811.6883117 1 1 811.6883117

Oil Desalter 1 811.6883117 1 1 811.6883117

Produced Water Recycle Pump 2 357.1428571 1 1 357.1428571

HP Flare Pump 2 33.89830508 1 1 33.89830508

LP Flare Pump 2 24.85875706 1 1 24.85875706

Treated Oil Pump 2 292.2077922 1 1 292.2077922

Gas Compressors 3 6277.056277 2 1 12554.11255

Lube & Glycol Transfer pump 2 9.523809524 2 1 19.04761905

Glycol circulation Pump 2 18.71345029 1 1 18.71345029

Cooling Medium Pump 2 227.2727273 1 1 227.2727273

Heating Medium Pump 2 259.7402597 1 1 259.7402597

Oil Circulation Pump 2 108.2251082 2 1 216.4502165

Air Scour Blower 2 66.51884701 1 1 66.51884701


Sulphate Removal Pump 3 1839.82684 3 1 5519.480519

Vacuum Pump 2 87.24100327 2 1 174.4820065

Water Injection Pump 3 6601.731602 3 1 19805.19481

Non Oxydizing Biocide dosing pump

2 3.807106599 2 1 7.614213198

FW maker HP Pump 2 324.6753247 1 1 324.6753247

Fresh water Pump 2 66.51884701 1 1 66.51884701

Produced Water Booster Pump 1 108.2251082 1 1 108.2251082

Gas Dehydration Package 1 378.7878788 1 1 378.7878788

Reflux condenser 1 11.9047619 1 1 11.9047619

Glycol Reboiler 1 216.4502165 1 1 216.4502165

Rich / Lean Glycol Exchanger 1 216.4502165 1 1 216.4502165

Glycol cooler 1 66.51884701 1 1 66.51884701

48779.78841

Table 6.4

The rest of the systems are not working in this case. So, total power requirement for load case 1

is 48780kw(app.).

LOAD CASE 2:PROCESSING PLANT +BALLAST+CRUDE SYSTEM WORKING

PROCESSING PLANT Total Qty Unit Power Unit in

Use Load Factor Power

Kw

Small Sized Pump 22 2.791878173 15 1 41.87817259








Slurry Pump 1 50.84745763 1 1 50.84745763


Oil Dehydrator 1 811.6883117 1 1 811.6883117

Oil Desalter 1 811.6883117 1 1 811.6883117


HP Flare Pump 2 33.89830508 1 1 33.89830508

LP Flare Pump 2 24.85875706 1 1 24.85875706

Treated Oil Pump 2 292.2077922 1 1 292.2077922

Gas Compressors 3 6277.056277 2 1 12554.11255







Air Scour Blower 2 66.51884701 1 1 66.51884701


Vacuum Pump 2 87.24100327 2 1 174.4820065


Non Oxydizing Biocide dosing pump 2 3.807106599 2 1 7.614213198

FW maker HP Pump 2 324.6753247 1 1 324.6753247

Fresh water Pump 2 66.51884701 1 1 66.51884701




Glycol Reboiler 1 216.4502165 1 1 216.4502165


Glycol cooler 1 66.51884701 1 1 66.51884701

48779.78841

BALLAST WATER CONTROL Total Qty Unit Power

Ballast Water Pump 4 974.025974 974.025974

OFFLOADING CRUDE CONTROL

Total Qty Unit Power

Crude Offloading Pumps 30 1086.580087 6519.480519

Tank Cleaning Pump 1 176.9480519 176.9480519

Portable Unloading Standby Pump 1 0 0

Table 6.5

The power consumption for load case2 is

(48779.78841+974.025974+6519.480519+176.9480519+0)=56450.24295Kw

LOAD CASE 3:PROCESSING PLANT +BALLAST+CRUDE SYSTEM

+ACCOMMODATION WORKING



Kw

Small Sized Pump 22 2.791878173 15 1 41.87817259








Slurry Pump 1 50.84745763 1 1 50.84745763



Oil Dehydrator 1 811.6883117 1 1 811.6883117

Oil Desalter 1 811.6883117 1 1 811.6883117


HP Flare Pump 2 33.89830508 1 1 33.89830508

LP Flare Pump 2 24.85875706 1 1 24.85875706

Treated Oil Pump 2 292.2077922 1 1 292.2077922

Gas Compressors 3 6277.056277 2 1 12554.11255






Air Scour Blower 2 66.51884701 1 1 66.51884701


Vacuum Pump 2 87.24100327 2 1 174.4820065



FW maker HP Pump 2 324.6753247 1 1 324.6753247

Fresh water Pump 2 66.51884701 1 1 66.51884701




Glycol Reboiler 1 216.4502165 1 1 216.4502165


Glycol cooler 1 66.51884701 1 1 66.51884701

48779.78841








ACCOMMODATION(1.5Kw/person, total 140 people)

N.A. N.A. 210

Table 6.6

LOAD CASE 4: ALL SYSTEMS WORKING EXCEPT BALLAST AND CARGO

SYSTEM


Use Load

Factor Power

Kw

Small Sized Pump 22 2.791878173 15 1 41.87817259









Slurry Pump 1 50.84745763 1 1 50.84745763


Oil Dehydrator 1 811.6883117 1 1 811.6883117

Oil Desalter 1 811.6883117 1 1 811.6883117


HP Flare Pump 2 33.89830508 1 1 33.89830508

LP Flare Pump 2 24.85875706 1 1 24.85875706

Treated Oil Pump 2 292.2077922 1 1 292.2077922

Gas Compressors 3 6277.056277 2 1 12554.11255






Air Scour Blower 2 66.51884701 1 1 66.51884701


Vacuum Pump 2 87.24100327 2 1 174.4820065



FW maker HP Pump 2 324.6753247 1 1 324.6753247

Fresh water Pump 2 66.51884701 1 1 66.51884701




Glycol Reboiler 1 216.4502165 1 1 216.4502165


Glycol cooler 1 66.51884701 1 1 66.51884701

48779.78841


Ballast Water Pump 4 974.025974 0



Crude Offloading Pumps 30 1086.580087 0

Tank Cleaning Pump 1 176.9480519 0


ACCOMODATION Total Qty Unit Power

Power assuming 1.5Kw per person 210 210

Electronic System Total Qty Unit Power

Main control Console 1 0.9 0.9

Engine Room Panel 1 3 3


Compass 0.6 0.6

Interior Communications 0.46 0.46

Radio 1.84 1.84

Battery Charger 0.7 0.7

Alarm 0.1 0.1

Smoke/Gas detactors 5 5

Other System Total Qty Unit Power

Sewage Grinder 1 2.1 2.1

Life Boat Winch(each winch 7men) 20(each 12.7) 25.4 25.4

Refrigeration compressor 1 23.1 23.1

Potable water Pump 10 10

Main Bilge, Fire, G.S. Pumps 3 149.3506494 149.3506494

Work Shop 1.63 1.63

Sewage Blower 1.4 1.4

Helideck 1 1

Total Power

49216.36906

Table 6.7

The total power consumption for load case 4 is 49216.36906Kw.

LOAD CASE 5: ALL SYSTEMS WORKING SIMULTANEOUSLY(EXCLUDING

EMERGENCY SYSTEMS)



Kw

Small Sized Pump 22 2.791878173 15 1 41.87817259








Slurry Pump 1 50.84745763 1 1 50.84745763


Oil Dehydrator 1 811.6883117 1 1 811.6883117

Oil Desalter 1 811.6883117 1 1 811.6883117


HP Flare Pump 2 33.89830508 1 1 33.89830508

LP Flare Pump 2 24.85875706 1 1 24.85875706

Treated Oil Pump 2 292.2077922 1 1 292.2077922

Gas Compressors 3 6277.056277 2 1 12554.11255







Air Scour Blower 2 66.51884701 1 1 66.51884701


Vacuum Pump 2 87.24100327 2 1 174.4820065



FW maker HP Pump 2 324.6753247 1 1 324.6753247

Fresh water Pump 2 66.51884701 1 1 66.51884701




Glycol Reboiler 1 216.4502165 1 1 216.4502165


Glycol cooler 1 66.51884701 1 1 66.51884701

48779.78841













Compass 0.6 0.6


Radio 1.84 1.84


Alarm 0.1 0.1




Life Boat Winch(each winch 7men) 20(each 12.7) 25.4 25.4




Work Shop 1.63 1.63



Helideck 1 1

Total Power 56886.8236

Table 6.8

LOAD CASE 6: EMERGENCY SUPPLY LOAD CASE

PROCESSING PLANT Total Qty Unit in Use Load Factor Power

Small Sized Pump 22 15 0 0

Wax Inhibitor Injection Pump 3 2 0 0

Demulsifier Injection Pump 2 1 0 0

Methanol Injection Pump 5 4 0 0

Chemical Transfer Pump 1 1 0 0

H.P Pump HP1(Manifold) 2 2 0 0

L.P Pumps LP1(Processing) 2 2 0 0

Return Reservoir Pump 1 1 0 0

Slurry Pump 1 1 0 0

Dehydrator feeding Pump 2 1 0 0

Oil Dehydrator 1 1 0 0

Oil Desalter 1 1 0 0

Produced Water Recycle Pump 2 1 0 0

HP Flare Pump 2 1 0 0

LP Flare Pump 2 1 0 0

Treated Oil Pump 2 1 0 0

Gas Compressors 3 2 0 0

Lube & Glycol Transfer pump 2 2 0 0

Glycol circulation Pump 2 1 0 0

Cooling Medium Pump 2 1 0 0

Heating Medium Pump 2 1 0 0

Oil Circulation Pump 2 2 0 0

Air Scour Blower 2 1 0 0

Sulphate Removal Pump 3 3 0 0

Vacuum Pump 2 2 0 0

Water Injection Pump 3 3 0 0

Non Oxydizing Biocide dosing pump 2 2 0 0

FW maker HP Pump 2 1 0 0

Fresh water Pump 2 1 0 0

Produced Water Booster Pump 1 1 0 0

Gas Dehydration Package 1 1 0 0

Reflux condenser 1 1 0 0

Glycol Reboiler 1 1 0 0

Rich / Lean Glycol Exchanger 1 1 0 0

Glycol cooler 1 1 0 0

0


BALLAST WATER CONTROL Total Qty

Ballast Water Pump 4 0


Total Qty

Crude Offloading Pumps 30 0

Tank Cleaning Pump 1 0

Portable Unloading Standby Pump 1 0

ACCOMODATION Total Qty

Power assuming 1.5Kw per person Consider only

emergency(.75kw/person) 105

systems of accomodation

Electronic System Total Qty

Main control Console 1 0.9

Engine Room Panel 1 3

Compass Also UPS Power=12.6Kw 0.6

Interior Communications 0.46

Radio 1.84

Battery Charger 0.7

Alarm 0.1

Smoke/Gas detactors 5

Other System Total Qty

Sewage Grinder 1 0

Life Boat Winch(each winch 7men) 20(each 12.7) Demand facor 1 for lifeboat winches=>

254

Refrigeration compressor 1 0

Potable water Pump 10

Main Bilge, Fire, G.S. Pumps 3 1493.506494

Work Shop 1.63

Sewage Blower 0

Helideck 1


for emergency

generator

Table 6.9

LOAD CASE 7: ESSENTIAL SUPPLY LOAD CASE

PROCESSING PLANT Total Qty Unit Power Unit in Use Load Factor Power

Kw

Small Sized Pump 22 2.791878173 15 0 0

Wax Inhibitor Injection Pump 3 28.24858757 2 0 0

Demulsifier Injection Pump 2 6.547619048 1 0 0


Methanol Injection Pump 5 303.030303 4 0 0

Chemical Transfer Pump 1 22.59887006 1 0 0

H.P Pump HP1(Manifold) 2 1417.748918 2 0 0

L.P Pumps LP1(Processing) 2 824.6753247 2 0 0

Return Reservoir Pump 1 22.59887006 1 0 0

Slurry Pump 1 50.84745763 1 0 0

Dehydrator feeding Pump 2 292.2077922 1 0 0

Oil Dehydrator 1 811.6883117 1 0 0

Oil Desalter 1 811.6883117 1 0 0

Produced Water Recycle Pump 2 357.1428571 1 0 0

HP Flare Pump 2 33.89830508 1 1 33.89830508

LP Flare Pump 2 24.85875706 1 1 24.85875706

Treated Oil Pump 2 292.2077922 1 1 292.2077922

Gas Compressors 3 6277.056277 2 0 0

Lube & Glycol Transfer pump 2 9.523809524 2 0 0

Glycol circulation Pump 2 18.71345029 1 0 0




Air Scour Blower 2 66.51884701 1 1 66.51884701

Sulphate Removal Pump 3 1839.82684 3 0 0

Vacuum Pump 2 87.24100327 2 0 0

Water Injection Pump 3 6601.731602 3 0 0

Non Oxydizing Biocide dosing pump 2 3.807106599 2 0 0

FW maker HP Pump 2 324.6753247 1 0 0

Fresh water Pump 2 66.51884701 1 1 66.51884701

Produced Water Booster Pump 1 108.2251082 1 0 0

Gas Dehydration Package 1 378.7878788 1 0 0

Reflux condenser 1 11.9047619 1 0 0

Glycol Reboiler 1 216.4502165 1 0 0

Rich / Lean Glycol Exchanger 1 216.4502165 1 0 0

Glycol cooler 1 66.51884701 1 0 0

1187.465752


Ballast Water Pump 4 974.025974 Ballast pump

function 0


Total Qty Unit Power as

emergency pumps

Crude Offloading Pumps 30 1086.580087 0

Tank Cleaning Pump 1 176.9480519 0








Compass 0.6 0.6


Radio 1.84 1.84


Alarm 0.1 0.1




Life Boat Winch(each winch 7men) 20(each 12.7) 25.4 254




Work Shop 1.63 1.63


Helideck 1 1


for esential generators

Table 6.10

SELECTION OF TPPL (Total Plant Peak Load)

LOAD CASE CASE DESCRIPTION POWER(Kw) CASE 1 Processing Plant Working 48779.78841

CASE 2 Processing Plant +Ballast and Crude Offloading Control Working 56450.24295

CASE 3 Processing Plant +Ballast and Crude Offloading Control +Accommodation 56660.243

CASE 4 All systems except Ballast and Crude Offloading 49216.36906

CASE 5 All systems working simultaneously(excluding emergency systems) 56886.8236

Max power CASE 6 Emergency Power Requirements 1877.736494

CASE 7 Essential Power Requirements 3196.802245

Table A6.11 The LOAD CASE 5 the power requirement is highest. So, TPPL=56886.8236


APPENDIX VII 1. Group technology

Group technology consist both type of production organization, product (or group) organization and Mass production organization. In group organization the worker and his equipment is fixed and the work object moves from one workstation to another and the intermediate products produced in this manner are combined to make the final product. A Mass production organization maximizes the use of mechanization, continuous flow lines, and specialization of activities at sequential workstations. Group technology is something which deals with both type of organization. Group technology can be seen as a concept in which the production facilities are organized in self contained groups or cells. Each self regulating group or cell is capable of producing a family of products of similar manufacturing characteristics. Each cell has a number of machines and workers who are capable of using several machines or process, thereby requiring less workers. The Group technology having following characteristic:

1. Components are classified into groups or families according to the production process by

which they are produced.

2. Work loads are balanced among production groups into which production facilities are

organized rather than between separate manufacturing operations.

3. Each cell works with a considerable degree of autonomy.

2. Panel line (Flat panel assembly)

Stiffened panels, consisting of plates attached to stiffeners, constitute a large percentage of structural fabrication work in a shipyard. So to improve the productivity at the block assembly stage the stiffened panels are produced in an automated flow line production facility called the panel line. This works with different work station. All work station use one sided butt welding for joining plates and gravity welding for stiffeners. Process is carried out in following step: Plate arrival, Alignment and Tacking: Plates after shot blasting arrive at this station. The plates are positioned, aligned and tack welded manually. Plate welding: The tack welded plates arrive at this station where one sided butt welding is carried out. Marking and Cutting: marking on the joined plate panel is carried out next. The marketing at this stage allows for a more accurate panel shape. Subsequently, the plate panel is cut to size, including deck opening, lightening holes, etc., using numerical control flame cutting machine. Egg Box Assembly of Stiffeners: on a parallel conveyor which is along side the plate panel line, the longitudinals and transverses are assembled together using lugs and jigs. Egg Box Stiffener Feed-in: the assembled egg-box of longitudinals and transverses is transferred on to the plate panel and positioned using overhead cranes. Welding of Stiffeners to Plate Panel: using gravity welding machine or other automatic welding machine. Inspection and Repair: the stiffened panel is checked for welding defects and accuracy at this stage. If required, minor repairs are carried out. Outfitting work like fitting of pipes, scaffolding brackets, lifting pads, etc. is performed at this stage.


END OF REPORT

THANKYOU.

ISODC, IIT Kharagpur Team, May 2008

Documents

Transcript of ISODC, IIT Kharagpur Team, May 2008