SABP-M-001

Best Practice

SABP-M-001 11 May 2008 Inspection Guidelines of Offshore Structures

Document Responsibility: Offshore Structures Standards Committee

Saudi Aramco DeskTop Standards Table of Contents 1 Introduction.................................................. 2 2 References................................................... 3 3 General......................................................... 3 4 Definitions..................................................... 4 5 Inspection Procedure.................................... 5 Table 1.0 - Inspection Guide.............................. 9 Table 2.0 - Recommended Periodic Inspection Intervals......................... 14

Developed by: Ala A. Al-Sharif Civil Engineering Unit/M&CED Consulting Services Department

Previous Issue: New Next Planned Update: TBD of 14 Primary contact: Sharif, Alaeddin Abdul Raouf on 966-3-8745321

Copyright©Saudi Aramco 2008. All rights reserved.

Document Responsibility: Offshore Structures SABP-M-001 Issue Date: 11 May 2008 Next Planned Update: TBD Inspection Guidelines of Offshore Structures

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1 Introduction

1.1 Purpose

This Practice establishes guidelines and recommended procedures for the inspection of Saudi Aramco offshore facilities above and below water to ensure that all facilities are adequately inspected on a regular basis as a general good engineering and safety practice and while in operation, including a general inspection of the jacket platform after installation and prior to commissioning of the platform.

1.2 Scope

This guideline formulates an integrated, general and non-prescriptive engineering approach to be utilized while maintaining, evaluating and re-qualifying existing Saudi Aramco offshore facilities/platforms to ensure an acceptable level of reliability. This guideline is based on the Recommended Practice for Planning, Designing and Constructing of Fixed Offshore Platforms according to the American Petroleum Institute (API) and the Petroleum and Gas industries – Fixed steel offshore structures by International Organization for Standardization (ISO).

1.3 Disclaimer

The material in this Best Practices document provides the most correct and accurate design guidelines available to Saudi Aramco which complies with international industry practices. This material is being provided for the general guidance and benefit of the Designer. Use of the Best Practices in designing projects for Saudi Aramco, however, does not relieve the Designer from his responsibility to verify the accuracy of any information presented or from his contractual liability to provide safe and sound designs that conform to Mandatory Saudi Aramco Engineering Requirements. Use of the information or material contained herein is no guarantee that the resulting product will satisfy the applicable requirements of any project. Saudi Aramco assumes no responsibility or liability whatsoever for any reliance on the information presented herein or for designs prepared by Designers in accordance with the Best Practices. Use of the Best Practices by Designers is intended solely for, and shall be strictly limited to, Saudi Aramco projects. Saudi Aramco® is a registered trademark of the Saudi Arabian Oil Company. Copyright, Saudi Aramco, 2002.

1.4 Conflicts with Mandatory Standards

In the event of a conflict between this Best Practice and other Mandatory Saudi Aramco Engineering Requirement, the Mandatory Saudi Aramco Engineering Requirement shall govern.


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2 References

This Best Practice is based on the latest edition of the references below, unless otherwise noted.

2.1 Industry Codes and Standards

American Petroleum Institute (API)

API RP 2A Recommended Practice for Planning, Designing and Constructing of Fixed Offshore Platforms

International Organization for Standardization (ISO)

ISO 19902: 2007(E) Petroleum and natural gas industries — Fixed steel offshore structures

3 General

3.1 The outlined procedure in sec. 5.0 is recommended to serve as the basis for above and underwater inspection program. This is done to monitor the adequacy of the corrosion protection system, check structural defects, accidental damages and evaluate the general condition of the facility. These inspections will help to safeguard human lives and properties, protect the environment and qualify the facilities for their intended service or extend their operating life.

3.2 Three types of inspection are recommended

(See Paragraph 5.3):

Type I : General above water visual inspection. Type II : General underwater visual inspection. Type III : Detailed underwater inspection.

3.3 A quick guide for inspection is outlined in Table 1.0, and the recommended inspection intervals are shown in Table 2.0.

3.4 Any findings during the inspection that may be of concern to the structural integrity of a facility, which may affect the safety of the personnel and the environment, should be referred to Consulting Services (CSD) and Inspection Departments (ID) for assessment.


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4 Definitions

Manned Platform: A platform which is continuously occupied by persons living on the platform (e.g., living quarter platforms).

Other Structures: Structures other than manned and unmanned platforms (dolphins, piers, trestles, free standing conductors, etc.).

Splash Zone: Area of a structure that is frequently wetted due to waves and tidal variations.

Unmanned Platform: A platform which may be occupied by persons but not living on the platform (other GOSP-platform, loading platform, metering platform, etc.).

AWS: American Welding Society.

ANSI: American National Standards Institute.

API: American Petroleum Institute.

ASME: American Society of Mechanical Engineers.

CP: Cathodic Protection.

DFIR: Design, Fabrication and Installation Records.

ISO: International Organization for Standardization.

NDT: Non-Destructive Testing.

ROV: Remote Operated Vehicles.

SCOUR: Removal of seabed soils caused by currents and waves.

SCR: Structure Condition Records


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5 Inspection Procedure

The following procedure should be used as a guideline in performing inspection surveys (above & underwater) for offshore facilities:

5.1 Planning and Personnel Qualification

Surveys should be planned and carried out at regular intervals (see Paragraph 5.4) by personnel who are proficient in Non-Destructive Testing (NDT) methods, possess survey experience and have demonstrated ability and experience by passing practical tests, or be qualified to the appropriate codes, such as AWS (D1.1-2002), ASME/ANSI or equivalent. Also, the observations by the facility operating and maintenance personnel should be incorporated in their survey reports. Adequate illustrations of the structures are essential for carrying out accurate inspection. This includes providing structural drawings for above and below water and clear location of items to be inspected, see also Paragraph 5.5.

Underwater survey should be conducted by skilled and qualified divers or/ and by means of Remote Operated Vehicles (ROV) under the supervision of qualified personnel or by divers. The NDT operator working underwater should be required to possess the following qualifications:

a. Certification in NDT methods.

b. Extensive diving experience and a minimum of two (2) years of experience in certified NDT work underwater.

5.2 Inspection Methods

In selection of the inspection method a number of parameters should be considered, including the joint geometry, applied stress, material thickness and location. An approved procedure for each inspection method should be developed for each job application using one or more of the following NDT methods:

5.2.1 Visual

5.2.2 Penetrant Technique (PT)

This is a useful method in detecting surface discontinuities such as cracks, porosity, etc.

5.2.3 Magnetic Particle Technique (MPT)

This method is useful for discontinuities that are open to the surface or which are slightly subsurface.


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5.2.4 Radiographic Technique (RT)

This method is useful for determining buried or through thickness discontinuities.

5.2.5 Ultrasonic Technique (UT)

This method is also useful for determining buried or through thickness discontinuities.

5.3 Inspection Types

5.3.1 Type I – General Above Water Visual Inspection

This inspection consists of general visual inspection of the structure above water to determine:

a. The effectiveness of the corrosion protection system, coating deterioration, damaged areas or excessive corrosion especially in the splash zone.

b. Indications of overloading, missing or damaged members.

If above water damage is detected and visual inspection is not sufficient, measurement and NDT should be used to determine the extent of the damage. Sufficient cleaning, such abrasive blasting, shall be carried out to remove heavy corrosion scale. Special attention should be paid to platform legs and members at the splash zone. If this inspection indicates possible underwater damage, a Type II inspection should be conducted.

5.3.2 Type II – General Underwater Visual Inspection

This inspection consists of general underwater visual inspection by ROV under the supervision of qualified personnel or by divers with head mounted cameras to detect the presence of any of the followings:

a. Metal separation due to fatigue damage at high stress area (e.g., tubular joints of primary and secondary members, can sections, etc.).

b. Excessive marine growth.

c. Member damage, i.e., dented, , flooded, ruptured/ missing members due to accident or environmental overload.

d. Seabed subsidence, settlements, scours, debris, gas/ oil seeps, etc.

e. Construction deficiencies.

f. Excessive anode depletion and corrosion due to faulty CP system.


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Detection of significant structural damage during Type II inspection should be subjected to further evaluation, and Type III inspection should be conducted as soon as possible.

5.3.3 Type III – Detailed Underwater Inspection

At this stage some or all of the following activities are carried out:

- Marine growth measurement,

- Scour size measurement,

- Wall thickness measurement,

- CP measurement and measurement of anodes diameter.

Pre-selected underwater areas of known or suspected damage based on structural analysis or of engineering concerns are subjected to thorough inspection and evaluation. These areas should be sufficiently cleaned of marine growth to allow accurate visual inspection, quantitative measurements and accurate NDT for crack detection, e.g., using MPT.

Table 1.0 should serve as a guideline for the specific items that should be addressed during the actual inspection.

5.4 Inspection Frequency

5.4.1 Periodic Inspection

The first annual inspection should be carried out within 12 months after the date of commissioning the offshore facility/ platform. Table 2.0 shows the recommended periodic inspection intervals which should not be exceeded unless longer intervals can be justified. Justification for changing the interval should be supported by the appropriate documents and retained by the facility proponent. In such cases, the following factors should be taken into account:

a. Original design criteria.

b. Present design criteria, service history and structural reserve strength.

c. Facility/ platform location and the criticality of the platform to other operations.

e. Facility classification as Manned, Unmanned platforms or free standing conductors.

d. Consequence of failure to human life, property, the environment, and/or conservation of natural resources.


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f. Well types (sour gas, high pressure, etc.).

5.4.2 Non-periodic Inspection

A Type I inspection should be conducted after exposure to excessive environmental loading.

A Type II inspection should be conducted upon completion of the initial drilling or workover, after severe accidental loading (boat collision, etc.), or one year after completion of a major underwater structural repair.

A Type III inspection should be conducted if the structure was subjected to abnormal loadings that may affect the structural members below water levels, e.g., accidental boat impact.

5.5 Record Keeping, Recommendations and Final Report

5.5.1 All relevant records of the structure history and the inspection reports should be retained by the facility proponent for the life of the facility. This should contain video tapes, photographs, measurements, damage descriptions, divers’ reports, etc. These records should be documented as the followings:

a. Design, Fabrication and Installation Records (DFIR)

This describes the structure as installed based on documentation of the design (D), fabrication (F), and installation (I) phases. This should contain a general description of the structure, design premises and calculations, description of materials, pile driving records, etc.

b. Structure Condition Records (SCR)

This serves as a data bank on the current condition of the structure. It contains records of any exceptional event that takes place during the structure service life. It also should summarize the findings from each inspection and address any areas/ items of concern which might be significant in subsequent inspections.

5.5.2 The evaluation of the platform condition and recommendations shall be based on the collected data from the above sources. The final report shall contain all the necessary information of the structure until the next inspection.

Revision Summary 11 May 2008 New Saudi Aramco Best Practice.


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Table 1.0 – Inspection Guide (s) = special reference to steel structures (c) = special reference to concrete structures

ITEM CODE

Significant Areas of Inspection Possible Defects Possible Reason/s

for Defects Possible Consequence

of Defects

A General inspection of structure

General or major defects that may impair the safety and integrity

- Static or cyclic

overloading - Collision, dropped

objects - Material deterioration

- Progressive development of defects due to re-distribution of force

- Accelerated deterioration

B Area of Repair

- Failure of repair material

- Rebar corrosion (c) - Cracking - Weld failure (s)

- Poor workmanship - Unsuitable materials

or repair procedure - Shrinkage (c) - unforeseen stress

concentrations

- Accelerated deterioration, corrosion, etc.

- Reduction in load bearing capacity

- leakage

C Area of inferior construction

- localized material deterioration

- Corrosion - Deformations

- Poor workmanship or method of

construction - Poor concrete quality

(c) - Dense Reinforcement

(c) - Design unsuitable

- Accelerated deterioration, corrosion, etc.

- Reduction in load

bearing capacity - leakage

D Area of high stress

- Cracking - Corrosion - Spalling of concrete

cover (c) - Signs of material

yielding

- Structure geometry - Unexpected stress

concentrations - Force redistribution

Progressive development of: - Cracking - Corrosion - Force redistribution - Leakage


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Table 1.0 continued

ITEM CODE



of Defects

E Area of cyclic stress

- Signs of material fatigue

- Cracking and spalling - Corrosion - Local structural failure

- Cyclic loading mainly from waves

- Vibration

Progressive development

of: - Structural failure - Deformation - Cracking - Corrosion - Spalling

F Welded joint with steel thickness > 50mm (s)

- Lamination - Cracks

- Local material defect - Cyclic loading - Poor workmanship

- Local and progressive structural failure

G Cut-outs/ penetrations (s)

- Cracking - Deformation of hole

- Overload - Unexpected stress

concentration

- Local cracking - Progressive structural

failure

H Bolted connection (s) Clamps (s)

- Loose or missing bolts - Corrosion - Deformations

- Poor workmanship - Non-secured nuts - Impact loads - Overload

- Loss of structural integrity

- Large deformations

I Structural members in compression

- Signs of member

buckling, i.e., excessive deformations

- Overload - Material creep

deformation (c)

- Structural failure of member

J Structure foundation (piles, anti-scour system)

- Scouring of seabed - Failure of pile/jacket

connections (s) - Seabed subsidence - Settlement - Signs of piping in soil

- Waves and current effects

- Poor workmanship or design of anti-scour system

- Overload - Emptying reservoir

- Excessive deformation

in piles (s) - Differential and total

settlement - Reduction in factor of

safety for foundation - Problems with

connected risers, pipelines and conductors due to displacements

- Reduced air gap


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Table 1.0 continued

ITEM CODE



of Defects

K

Corrosion protection system (anodes, impressed current, inhibitors etc.) (s)

- Missing or eroded

anodes - Defective anode

cables - Defect in inhibitor

system - Marine growth on

anodes

- Unforeseen current drainage

- Inefficient anodes - Malfunction of inhibitor

system

- General or local corrosion

L

Areas for potential measurement (selected points, reference points, reference electrodes) (s)

- Insufficient polarization of steel or sacrificial anodes

- Local or general under capacity in current density from anodes

- Missing or eroded anodes

- Inadequate CP

- General or local corrosion

M Areas for material thickness measurement (s)

- Reduction in material thickness

- Erosion/ corrosion

Internally and externally

- Abrasion

- Reduction in load bearing capacity

N Areas with signs of corrosion

Signs of corrosion on: - Steel jacket and deck

Structures (s) - Steel gratings (s) - steel parts embedded

in concrete (c)

- Malfunction of

corrosion protection system (Refer to K and L)

- Poor quality of concrete (c)

- Stress concentrations - Fatigue - Defective coatings

- Material deterioration - Reduction in material

thickness - Reduction in load

bearing capacity - Spalling of concrete (c) - Initiate cracking in welds

(s)


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Table 1.0 continued

ITEM CODE



of Defects

O Construction joints (welds, construction joints)

Concrete joints:

- Leakage - Spalling - Corrosion of

reinforcement Steel welds:

- Cracks - Corrosion

- Poor workmanship in cleaning of joints and compaction of concrete

- Poor workmanship or design

- Weld hardening - Inherent defects

- Accelerated leakage, leaching or corrosion

- Propagation of cracks - Accelerated corrosion

P Splash zone of structure

- Corrosion - Deterioration of

material and coatings - Signs of mechanical

damage - Monel sheeting

- Corrosive/ erosive

environment with wetting/ drying cycles

- Mechanical damage due to uncontrolled maneuvering of ships/ boats

- Accelerated corrosion/erosion

- Spalling of concrete (c) - Reduction in load

bearing capacity

Q Area of mechanical damage (e.g., from abrasion, collision)

- Spalling of concrete (c)

- Abrasion on concrete and steel

- Buckles and dents in Steel structure

- Corrosion

- Abrasion due to

anchor wires, dumped objects, etc.

- Collision by floating objects, falling or dumped objects, fishing equipment, etc.

- Waves and current

- Corrosion - Reduction in load

bearing capacity

R Embedded steel parts in concrete (c)

- Corrosion of steel and connected reinforcement

- Spalling of concrete

- Failure of coating,

inadequate cathodic protection

- Steel parts in direct contact with reinforcement

- Corrosion of reinforcement

- Failure of embedded steel parts.


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Table 1.0 continued

ITEM CODE



of Defects

S Coatings (s)

- Coating defects - Spalling - Cracks - Deterioration - Puncture - Adhesion failure

- Poor workmanship during application of coating

- Mechanical damage - Chemical

deteriorations

- Localized or general failure of coating

- Accelerated corrosion and deterioration of coated material

T Connection deck/ substructure (c)

- Cracking/ spalling - Corrosion - General failure of

connection

- Inherent areas of

inferior quality from Construction structure geometry

- stress concentrations

- Gradual failure of connection

U Instrumentation

- Marked changes in trends for results, e.g., response, pore pressures, settlements

- Failures in structure or foundation leading to changes in mass and/or stiffness

- Changes in foundation behavior

- Not applicable (defect to be confirmed by visual inspection)

V Areas suspect to internal corrosion (s)

- Reduced material

thickness - Cracks in material - Localized corrosion

attack and pitting

- Corrosivity of internal milieu

- Reduced load bearing capacity

- Propagation of cracks

W Areas of marine growth

- Corrosion related to Marine growth

- Increase in structure geometry and mass

- Favorable environment

- Increase wave forces on

structure - Overloading on

horizontal structural members (s)

- Change in response, due to mass increase (s)


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Table 2.0 – Recommended Periodic Inspection Intervals

Inspection Type I II III

Manned Platforms 1 yr. 3 thru 5 yrs. 6 thru 10 yrs.

Unmanned Platforms 1 yr. 5 thru 10 yrs. 11 thru 15 yrs.

Other Structures 3 yr. 7 thru 10 yrs. 15 thru 20 yrs.

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