Robust Risk Analysis from a engineering point of vie 2013/Brannsikkerhet/2... · systems/PDMS...

Confidential © 2013 Aker Solutions Preferred partner

Preferred partner

Robust Risk Analysis from a engineering

point of view Stavanger 24th of October

Linda Fløttum & Tore Svidal


What is overall important to a project?

■ Critical decisions at the right time

■ Maturity requirements per milestone

■ Predictability in: ■ Design development

■ Deliverables

■ Quality

■ Cost

■ Develop a project that meets National Regulations and Clients

Requirements and which provides a good as possible working

environment, is inherently safe with as low as possible risk for people

and the environment

25 October, 2013 Slide 2


What is overall important to expect from a Risk Analyst

■ Experienced and well qualified in general and with expertise also to: ■ Qualitatively rank different design proposals in the feasibility, concept

and FEED phases

■ Propose alternatively design solutions

■ Provide the project with DAL values at the end of the FEED phase

which is likely to be valid when “Final As Built” deliverables are

completed

■ Flexibility to rapidly perform additional analysis and assessments as

e.g. part of ALRP evaluations

■ Willing to locate key risk analyst personnel in the same office as

engineering is performed

■ Have the right tools and methods

■ Can provides the project with correct and sufficiently robust results



FEED

Fabrication

Assy &

Hook-up

AFC

Detail Engineering

Procurement

Align contract and Project Execution Model milestones

Ready for

Tow Start

FEED

Class II cost

estimate Hull to

Hook-up

Yard/Mating

PO Long Lead

CA EP(C)

Contract Milestones

Milestones

Modules to

Hook-up

Yard

Hook-up &

Completion

1A 1B 1C 1D

2A 2B 2C

3A 3B 3C

4A 4B 4C

5A 5B 5C 5D

Feasibility &

Concept

System

Definition

Detailing &

Fabrication

Assembly/

Erection

System

Completion

Slide 5

2 6 10 14 14 5 8

“Freeze” DAL’s As built IFC drawings

Duration [months]


Project Execution

A new oil or gas discovery

Slide 6

■ Main project goal:

■ The best alternative solutions for how to bring up the oil and

gas from the reservoir on a safe and reliable manner to be

developed.

■ Different solutions will be evaluated.

■ Concept to be developed to a ~ +/- 30% cost estimate.

■ Robust Analysis:

■ Qualitatively assist engineering to select the best alternative

solution.

■ Quantified risk analysis may be introduced for special

challenging concept

■ Rank different concepts.

■ Propose alternative and better solutions.


Project Execution

Slide 7

■ Main project goal:

■ Project matures the selected concept to ensure the correct

size of the production unit.

■ Concept to be developed to a ~ +/- 20% cost estimate.

Provide the project with DAL values at the end of the FEED

phase which is likely to be valid when “Final As Built”

deliverables are completed

Event Exposed

Area

Items to be Protected Design Load

Heat Load

(kW/m2)

Duration

(Minutes)

Fire at

Process area

Main deck

Process area

from

EL50.500

and above

- Main deck

- Main loadbearing structure

- Critical equipment/piping

250/150

250/150

250/150

20 + 40

20 + 40

20 + 40


■ Quantified risk analysis is introduced

■ Rank different design alternatives for the selected concept

and assist engineering to select the best alternative

solution

■ Establish sectionalisation principles topside and need for

sectionalisation on production import and export lines (e.g.

SSIV)

■ Establish Safety Strategy and Performance Standards

■ Establish DAL for input to engineering design and

procurement of long lead items


Project Execution

Slide 8

■ Main project goal 2A:

■ Project confirms the best concept

■ All systems needed on the production units are defined

■ Procurement of most important equipment ( priority1)

where engineering information is needed, or with long

delivery time


■ Quantified risk analysis to be started early in the detail

engineering phase.

■ “Confirm/verify and detail out DAL’s

■ Assist in ALARP evaluations

■ Rank different design alternatives for the selected concept

and assist engineering to select the best alternative

solution

■ Confirm sectionalisation segments topside and need for

sectionalisation on production import and export lines (e.g.

SSIV)

■ Start to perform and establish segment evaluation vs.

volumes, blowdown duration, flare height and radiation

levels.

■ Continue to provide DAL’s for input to engineering design

and procurement


Project Execution

Slide 9

■ Main project goal 2B:

■ The design of main steel structures are completed.

■ All systems needed on the production units are defined.

■ Procurement of priority 2 equipment where engineering

information is needed.

24VG001

Våtgass

Væskeutskiller

HC: 12.3 tonn

20VA001

1.trinns separator

HC: 94 tonn

24PA001A/B

HC:< 1 tonn

24ESV1025

24ESV1031

24ESV1036

24ESV1022


■ Quantified risk analysis and emergency preparedness

analysis continues.

■ “Confirm/verify and detail out DAL’s.


and procurement .

■ CFD evaluation related to fire and response analysis

versus structures and hydrocarbon segments

■ Continue to perform and establish segment evaluation vs.

volumes, blowdown duration.

■ Assist in ALARP evaluations.


Project Execution

Slide 10

■ Main project goal 2C:

■ The P&IDs and global design are completed

■ All supplier information with interfaces are frozen

■ Procurement of priority 3 equipment


■ Quantified risk analysis and emergency preparedness

analysis continues.



and procurement .

■ CFD evaluation related to fire analysis finalished.

■ Response analysis versus structures and hydrocarbon

segments finalised versus main structural structures

■ Finalise hydrocarbon segment evaluation vs. volumes,

blowdown duration for large bore lines.



Project Execution

Slide 11

■ Main project goal 3A:

■ Design of outfitting arrangements and small items

■ Detail design completed

■ Issue of all drawings for fabrication


■ Quantified risk analysis and emergency

preparedness analysis finalised for detail

engineering phase.


■ Response analysis versus structures and

hydrocarbon segments finalised versus secondary

and outfitting structures

■ Finalised hydrocarbon segment evaluation vs.

volumes, blowdown duration for all lines.



Project Execution

Slide 12

■ Main project goal 3B:

■ The fabrication yard performs shop engineering

and preparations for fabrication

■ Engineering assists the fabrication yard


■ Update analysis according to introduced changes

■ No change….


Project Execution

Slide 13

■ Main project goal 3C & 3D:

■ Pre-fabrication of steel sections

■ Assembly of steel sections to modules

■ Equipment and system installation




■ No change….


Project Execution

Slide 14

■ Main project goal 4A – 4C:

■ Assembly and hook-up of modules

■ Hook-up installation of equipment and systems




■ No change….


Project Execution

Slide 15

■ Main project goal 5A – 5C:

■ Onshore/at-shore Commissioning of equipment and

systems

■ Preparation for tow-out

■ Tow-out

■ Offshore installation and commissioning

■ As-built documentation and contract close-out


■ As Built


■ To much optimisation can be introduced: ■ Simulate a few fires and use the result in structural response analysis

■ Structural response simulations concludes that PFP is not required

■ But

■ If explosion occurs during start-up of fire is the structural response

analysis fully valid? Structure may have deflected rather much…

■ Is this robust or ALARP?

Robustness


Loss of

containment

Explosion

Fire

Ignition


PFP epoxy application cost

■ Correct timing: Application cost for 1 m2 epoxy PFP with a thickness

of 8 mm is in the order of NOK 4.500,- m2

■ Incorrect timing: In the order of 2 to 3 times cost of as indiciated for

correct timed PFP application

■ Remove epoxy PFP: ■ Takes from 30 minutes to cut off cutting machine to 3 hours with water

jetting. Approximately 3 person required.



Project cost and resource timing

Slide 18 Slide 18

Ability to

influence cost Project cost

Time

E P C I C Operation Front end

studies FEED

Confidential © 2013 Aker Solutions Preferred partner 25 October 2013 Slide 19

Why is it challenging to make robust risk analysis?

Some project examples..


Example: Leak frequency

■ The leak frequency is the one of the parameters in the risk analysis

with largest influence on the risk picture (and hence’s DALs!)

■ The leak frequency is estimated by counting the number of leak

sources from P&IDs

■ Further the “DNV leak frequency model” (industry practice) is used to

estimate the leak frequency based on statistical failure rates for

different leak sources (valves, flanges etc.)

25 October 2013 Slide 20

Challenge 1: How to ensure that the number of leak sources

is estimated similarly independent of person/Company

performing the calculations?

Challenge 2: How to estimate the increase in number of leak

sources from early stage to as built?


Counting of leak sources

■ Defined “rules” for performing

the counting by each sub-

contractor

■ Time demanding calculations &

“manual work”

■ Relatively inexperienced

personnel often responsible for

the calculations

■ Variation in results observed for

the same basis

Need for a industry practice?

Possible to utilize engineering

systems/PDMS better?


Example of equipment count

Confidential © 2013 Aker Solutions Preferred partner 25 October 2013 Slide 22

Increase in the number of leak sources throughout

the project

P&ID gas export meeting, FEED phase

P&ID gas export meeting, detail engineering

■ Some challenges: ■ Only large dimension piping

modeled in early stage

■ Many details/leak sources

missing (e.g. instruments,

valves, flanges)

■ Vendor P&IDs not available

before late detail eng.

■ No common industry method

to estimate increase in leak

sources & limited with

experience data

■ Normally the risk analysis

contractor makes the

assumption

■ Critical assumption for the

project


Relevance of leak frequency model

■ Estimation of leak frequency requires a lot of resources and it is

challenging to “get it right”

■ And even if we “get it right”, is this the best estimate of the leak

picture for the installation? ■ Is the leak frequency proportional with the number of leak sources?

■ Or is other factors also important for the leak frequency, e.g. ■ Safety & operation philosophy and culture

■ Variation in operation modes

■ Quality of design & fabrication

■ One advantage with the current leak frequency model is the focus on

reducing the number of leak sources

■ On long term basis: could a more simple and robust model be used? ■ Predicable for the project

■ Robust safety design



Example: Congestion level in an explosion analysis

■ The congestion level inside the process areas is very important for

the resulting explosion pressure

■ The congestion level in the 3D model will increase until «as built»

■ Explosion analysis performed at an earlier stage in the project must

assume an expected increase in congestion level until «as built»


Challenge: the design explosion

loads will be «frozen» at an early

stage in the project

This assumption is, hence, very

critical for the project


Increase in congestion level – Project example

■ A significant increase in congestion level from detail engineering to

as built was reported

■ The assumption in detail engineering appears not to have been be

conservative enough

■ The change resulted in a significant increase in explosion pressure

■ Project was «saved by» a significant margin from dimensioning

accidental load to design accidental load



Example: Explosion analysis in concept/FEED phase

■ The 3D model will be immature at this stage

■ Important to use a representative and conservative congestion level

■ It is desired to a have a significant margin to the acceptance criterion

at this stage


3D modell in early phase (concept) 3D modell as built


How to add extra geometry to reflect as built?


■ Different methods

■ Normally, the risk analysis contractors have their database with as

built platforms, and corresponding congestion levels

■ Is the reported/read equipment density from FLACS cofile utility a

«real» equipment density? ■ Known limitations in FLACS utility (used for density reporting) should be

accounted for

■ E.g. cylinders inside enclosed boxes may lead to overestimation

Example:

compressor

with 104 m

piping inside


Results from a concept/FEED explosion analysis

Explosion load on firewall (4 x 4 m panel)



Explosion analysis in concept/FEED phase

■ Important with a good method to establish representative equipment

density in the early phases of the project

■ Overestimation of equipment density may lead to too high explosion

pressures, and possible non-feasible concepts ■ In particular this applies for large process areas

■ Underestimation of equipment density may lead to significant

challenges later in the project



Reflections - Industry

■ The fire and explosion analyses tend to be more and more complex ■ Are we on the right track?

■ Does this gives us increased safety level?

■ Are we optimizing too much?

■ What happens with the traceability of the analysis?

■ Need for more industry specific standards? ■ Calculation/estimation of number of leak sources

■ Standardization of “generic” assumptions, e.g. equipment density

■ Method for performing fire and explosion analysis

■ Are enough recourses used on analysis in the early stages of the

project?

■ Changes in method/best practice over time: ■ Challenge for a project when increase in risk level occur without any

design change

■ Openness about of causes of increase important



Reflections – Engineering

■ Set more stringent requirements to the risk analysis sub-contractor

■ Be more involved in the risk analysis execution ■ Take more responsibility for the assumptions

■ Get own experience data (e.g. equipment density and increase in

number of leak sources over time)

■ Increase risk analysis competency in-house

■ Possibility of doing parts of risk analysis by in-house team.



Reflections - Risk analysis sub-contractors

■ Make robust assumptions in close cooperation with engineering / oil

company

■ Be willing to work integrated with the project

■ Ensure experienced personnel and secure continuity

■ Increase competency about project execution

■ Be open about uncertainty in the analysis

■ Communicate results clearly

■ Make transparent and traceable analysis



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Slide 33 25 October, 2013

Robust Risk Analysis from a engineering point of vie 2013/Brannsikkerhet/2... · systems/PDMS...

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