Report 2012_3363_Guideline for Inspection of Decommissioned Offshore Structures

DET NORSKE VERITAS

TM

R EPORT EPORT GUIDELINE FOR INSPECTION OF DECOMMISSIONED DECOMMISSIONE D OFFSHORE STRUCTURES

NORSK OLJE OG GASS

R EPORT EPORT NO./DNV R EG EG NO.: 2012-3363 / 13XE6KG-4 R EV EV 0, 2013-07-03

Trusted by over 1 million members

Try Scribd FREE for 30 days to access over 125 million titles without ads or interruptions! Start Free Trial Cancel Anytime.



























DET NORSKE VERITAS Report for Norsk Olje og Gass Guideline for inspection of decommissioned offshore structures

MANAGING RISK

Table of Contents

Page

1

GENERAL .............................................. ..................................................................... .............................................. .............................................. .............................................. ....................... 1 1.1 Introduction ............................................. .................................................................... .............................................. .............................................. .................................... ............. 1 1.2 Scope ........................................... .................................................................. .............................................. .............................................. ............................................... .......................... 2 1.3 Objective and use............................................. .................................................................... .............................................. .............................................. ............................ ..... 2 1.4 Structure of document ............................................ ................................................................... .............................................. ............................................ ..................... 2

2

TERMINOLOGY AND DEFINITIONS ....................................... .............................................................. ............................................. .............................. ........ 3

3

ABBREVIATIONS............................................ ................................................................... .............................................. .............................................. ................................... ............ 4

4

AREAS TO BE INSPECTED ............................................ ................................................................... .............................................. .......................................... ................... 5 4.1 Structural strength....................... strength.............................................. .............................................. .............................................. ................................................ ........................... 5 4.2 Corrosion ............................................. .................................................................... .............................................. .............................................. ........................................ ................. 7 4.3 Inspection Technology .............................................. ..................................................................... .............................................. ......................................... .................. 7 4.4 Other ............................................. .................................................................... .............................................. .............................................. .............................................. ......................... 8

5

INFORMATION GATHERING................................ ....................................................... .............................................. .............................................. ........................... .... 9

6

SELECTION OF AREAS ........................................ ............................................................... .............................................. ............................................. ........................... ..... 10 6.1 Basis for selection ........................ ............................................... .............................................. .............................................. .............................................. ....................... 10 6.2 Workshop – Selection of inspections inspec tions ................................................. ........................................................................ ..................................... .............. 11 6.3 Documentation............................................. ..................................................................... ................................................ ............................................. ............................ ....... 11

7

PREPARATIONS AND EXECUTION OF INSPECTIONS ........................................... ........................................................... ................ 12 7.1 Group A – Structural Strength .......................................... ................................................................ ............................................ ................................. ........... 13 7.1.1 General ............................................. .................................................................... .............................................. .............................................. .................................. ........... 13 7.1.2 A.1 Low fatigue lives and/or reported cracks ....................................... .............................................................. ........................... .... 13 7.1.3 A.2 Grout connection between leg and pile ................................ ........................................................ ..................................... ............. 15 7.1.4 A.3 Pile/sleeve connections.............................................. ..................................................................... .............................................. ......................... .. 16 7.1.5 A.4 Piles ............................................ ................................................................... .............................................. .............................................. ................................. .......... 17 7.1.6 A.5 Members Me mbers with unintended flooding ............................................. .................................................................... ............................. ...... 18 7.1.7 A.6 Splash zone (fatigue) ..................................... ............................................................ ............................................... ..................................... ............. 19 7.1.8 A.7 Mechanical damaged structural members ............................... ....................................................... .................................. .......... 19 7.1.9 A.8 Grout reinforced structural components .............................................. .................................................................... ...................... 20 7.1.10 A.9 Pile to topside connection/condition of splice connections....................................... ....................................... 22 7.1.11 A.10 Ring stiffened joints .......................................................... ................................................................................. ...................................... ............... 22 7.1.12 A.11 Single sided welds ..................................... ............................................................ .............................................. ....................................... ................ 23 7.1.13 A.12 Closure welds ............................................................. .................................................................................... ............................................. ...................... 24 7.1.14 A.13 Conductors, risers and caissons caiss ons – structural condition........................................... ............................................. 25 7.1.15 A.14 Cast joints ........................................... .................................................................. .............................................. .............................................. ....................... 25
















MANAGING RISK

7.2.1 General ............................................. .................................................................... .............................................. .............................................. .................................. ........... 28 7.2.2 B.1 CP system .............................................................. ..................................................................................... .............................................. ............................. ...... 28 7.2.3 B.2 Coating....................... Coating.............................................. ............................................... ............................................... .............................................. .......................... ... 30 7.2.4 B.3 Coating repair ............................................................... ...................................................................................... ............................................. ...................... 31 7.2.5 B.4 Splash zone (corrosion) .............................................. ..................................................................... .............................................. ......................... 31 7.2.6 B.5 Riser Ris er and riser r iser clamps (corrosion) ( corrosion) ........................................... .................................................................. .................................. ........... 32 7.3 Group C – Inspection Technology.............................................. ..................................................................... ............................................. ...................... 33 7.3.1 General ............................................. .................................................................... .............................................. .............................................. .................................. ........... 33 7.3.2 C.1 Details that have inspection findings from operation ............................................. ................................................ ... 34 7.3.3 C.2 Areas of difficult/challenging underwater inspection ............................................... ............................................... 35 7.3.4 C.3 Verification of new inspection techniques ........................................................ ................................................................ ........ 35 7.4 Group D – Other ...................................... ............................................................ ............................................ ............................................. .................................... ............. 36 7.4.1 D.1 Bolts ................................... .......................................................... .............................................. .............................................. .......................................... ................... 36 7.4.2 D.2 Repair clamps ........................ ............................................... .............................................. .............................................. ...................................... ............... 36 7.4.3 D.3 Marine growth ............................................ ................................................................... .............................................. ........................................ ................. 37 8

POST-PROCESSING OF DATA ................................................ ...................................................................... ............................................. ............................... ........ 38 8.1 Group A - Structural strength ...................................... ............................................................. .............................................. ..................................... .............. 38 8.1.1 Evaluation of methods for structural calculations .......................................... ............................................................ .................. 38 8.1.2 Grout connections ............................................ ................................................................... .............................................. ......................................... .................. 38 8.2 Group B – Corrosion ........................................................... .................................................................................. .............................................. ............................. ...... 38 8.2.1 CP system ......................................................... ................................................................................ .............................................. ......................................... .................. 38 8.3 Group C – Inspection Technology.............................................. ..................................................................... ............................................. ...................... 38

9

STORAGE OF RESULTS ........................................... .................................................................. ............................................... ............................................ ...................... .. 39 9.1 Group A - Structural strength ...................................... ............................................................. .............................................. ..................................... .............. 39 9.2 Group B – Corrosion ........................................................... .................................................................................. .............................................. ............................. ...... 41 9.3 Group C – Inspection Technology.............................................. ..................................................................... ............................................. ...................... 43 9.4 Group D – Other ...................................... ............................................................ ............................................ ............................................. .................................... ............. 43

10

REFERENCES............................................. .................................................................... .............................................. .............................................. ....................................... ................ 44

Appendix 1:

Example format for workshop

Appendix 2:

Checklist for workshop
















MANAGING RISK

1

GENERAL

1.1 Introduction Many offshore structures are approaching the end of their original design life. In the coming years these will either be decommissioned or their operating lifetime will be extended. . In April 2010 the PSA activities regulation §50 was published, ref. /1/: “When facilities are disposed of, the operator shall carry out studies of the structure’s condition. The results shall be used to assess the safety of similar facilities.” In the guidance note to §50 it is specified that “ the examinations should particularly be carried out with a view towards projected new facilities and use of facilities beyond their original planned lifetime in mind ”. ”. PSA has however not specified what type of inspection which shall be performed. PSA expects that the industry identifies areas on decommissioned structures which should be inspected/tested to provide information of general value for life extension and design of similar facilities. The industry should organize experience transfer and make relevant data available to ensure that all operators learn from these inspections. This guideline has been financed by NOG and prepared in co-operation with the industry in order to establish a common set of criteria for which areas to inspect on decommissioned structures, when to inspect, what type of inspections that should be performed and how to report the results to ensure that the lessons learned can be incorporated into the inspection and maintenance program on structures which are intended to operate beyond the original design life. Over time the experience and learning from decommissioned structures may also be utilised in design of new structures. Inspection of decommissioned structures is a unique opportunity to investigate how the structures actually have performed over 20-40 years operation; were the designs adequate or unfavourable? The following is examples of what may be possible to learn and obtain: 

Relation between design calculations and real conditions; i.e. how the structure have performed



Increased knowledge related to offshore repair and reinforcement solutions



Confirm condition of non-accessible areas (e.g. piles, bolts/fasteners, clamps)



Verify inspection findings from operation



Sharing information via uniform collection of data

Inspection of structures brought onshore will provide added value and over time; 





contribute to increase the confidence to methodologies and criteria used in design contribute to increase the confidence to modern ‘state-of-the-art’ methodologies and criteria to document safe life extension help the operators to direct the inspections and maintenance to the most important areas
















MANAGING RISK



contribute to reduce the extent of inspections

1.2 Scope The purpose of the guideline is to establish a common approach for planning, execution and documentation of inspection of decommissioned jacket structures. The guideline is applicable for all structural parts of the jacket structures, including topside structures. Topside process equipment is not covered by this guideline.

1.3 Objective and use The project specific decommissioning plan shall include the extent of inspection that shall be performed on the decommissioned structure. This guideline should be be used to decide which areas of the decommissioned jacket structures that shall be inspected and what type of inspections that shall be performed. This guideline also specifies what type of information that should be stored in relation to these inspections. The intention is to ensure a common reporting of data so that sharing of information for future assessments is possible.

1.4 Structure Structure of document Section 4 lists all candidate areas for inspection which is covered in the guideline. Each area has a dedicated designation/ID which will follow this area for inspection in the guideline. Section 5 describes and lists the type of information that should be gathered prior to the selection of areas to be inspected. Section 6 describes how the selection of areas for each structure shall be performed as part of the cessation project. Section 7 gives details of how the inspections defined in Section 4 shall be performed. This Section is also intended to be used during the selection of areas for inspection. Section 8 describes how the data should be post-processed. Section 9 describes how the results should be stored and reported. Figure 1-1 gives an illustration of the work flow for this guideline.


















MANAGING RISK

Figure 1-1

2

Illustration of work flow for this guideline.

TERMINOLOGY AND AND DEFINITIONS

may

indicates a permissible course of action

shall

indicates a mandatory requirement

should

indicates a preferred course of action


















MANAGING RISK

3

ABBREVIATIONS

ALS

Accidental Load Limit States

CP

Cathodic Protection

DFF

Design Fatigue Factor

DFI

Design, Fabrication, Installation

ET

Eddy Current Testing

FLS

Fatigue Limit States

FMD

Flooded Member Detection

MPI

Magnetic Particle Inspection

MSF

Module Support Frame

MT

Magnetic Particle Testing

NDE

Non Destructive Examination

NDT

Non Destructive Testing

NOG

Norsk Olje og Gass

POD

Probability Of Detection

PSA

Petroleum Safety Authority

SCF

Stress Concentration Factor

ULS

Ultimate Limit States

UT

Ultrasonic Testing

VE

Visual Examination

VT

Visual Testing


















MANAGING RISK

4

AREAS TO BE INSPECTED

The candidate areas for inspection have been classified into 4 groups: Group A:

Structural strength

Group B:

Corrosion

Group C:

Inspection technology

Group D:

Other

Each area of inspection has been given a dedicated ID that will follow this area of inspection throughout the document. Each area for inspection has been given an inspection code: Code 1:

Minimum recommended requirement; i.e. should be performed on all structures.

Code 2:

Supplementary inspection; up to project to decide if inspection shall be performed based on checklists given in Appendix 2 and engineering judgement.

Code 3:

Supplementary testing; laboratory testing which is up to project to decide if should be performed.

Inspection areas with Code 1 and 2 are detailed further in this document. Inspection areas with Code 3 will require development of test procedures and is not covered in more detail in this guideline.

4.1 Structural strength Table 4-1 lists the candidate areas for inspection defined in the Group A “structural strength”. Table 4-1 Candidate areas for inspection defined in Group A – Structural Strength. ID Code Areas to be inspected Purpose A.1 1 Low calculated fatigue Increase understanding of fatigue phenomena to lives and/or reported improve fatigue analysis methods. See Sec. 7.1.2. cracks A.2 1 Grout connection between Check how grout has behaved. Check that the leg and pile assumptions made in design are acceptable. See Sec. 7.1.3. A.3 1 Pile/sleeve connections Check how grout has behaved. Check that the assumptions made in design are acceptable. See Sec.


















MANAGING RISK

ID

Code

Areas to be inspected components

A.9

2

A.10

2

Pile to topside connection/condition of splice connections Ring stiffened joints

A.11

2

Single sided welds

A.12

2

Closure welds

A.13

2

A.14 A.15

3 3

Conductors, Risers, Caissons - structural condition Cast joints Materials and welding

A.16

3

Material test of highly loaded parts

A.17

3

Measurement of residual stresses

A.18

3

Test of corroded material

Purpose experience for selection of grout material and testing for later grout operations. See Sec. 7.1.9. Verify how these connections have worked. See Sec. 7.1.10.

Check the condition of the inner ring stiffeners with the objective to validate the fatigue analysis procedure for the stiffener itself and the weld between stiffener and chord. See Sec. 7.1.11. Check the condition of the root area in single sided welds with the objective to validate the fatigue analysis procedure. See Sec. 7.1.12. Welds made under difficult condition in the yard with limited NDT. Possible sites for fatigue cracking in life extension. See Sec. 7.1.13. To get an overview of the structural condition of the conductors/risers/caissons. Main focus area is connection point to structure. See Sec. 7.1.14. Confirm quality of cast joints. See Sec. 7.1.15. Knowledge about the steel quality and quality of welding of steels used in early platforms. See Sec. 7.1.16. Establish stress/strain curves to assess possible ageing. Perform fatigue testing to establish remaining fatigue life. See Sec. 7.1.17. Improve understanding of the residual stresses in a structure that has served for several years in order to remove possible conservatism in the assessment methods. See Sec. 7.1.18. Establish S-N curves for structures with free corrosion. See Sec. 7.1.19.


















MANAGING RISK

4.2 Corrosion Table 4-2 lists candidate areas for inspection defined in the Group B “Corrosion”. Table 4-2 Candidate areas for inspection defined in Group B – Corrosion. ID Code Areas to be inspected Purpose B.1 1 CP system Knowledge of contingency of the CP-system can be utilised for lifetime extension of other structures. See Sec. 7.2.2. B.2 1 Coating Improve knowledge of coating degradation. See Sec. 7.2.3. B.3 1 Coating repairs Evaluate if repair methods are good/poor. Can be used as input on other existing structures. See Sec. 7.2.4. B.4 1 Splash zone (corrosion) Establish corrosion rates to be able to document longer life and larger capacity for existing structures. See Sec. 7.2.5. B.5 2 Riser and riser clamps Establish data on how risers and riser clamps perform (corrosion) with respect to corrosion in order to improve assessment/inspection methods. See Sec. 7.2.6. B.6 2 Waterfilled closed Inspection of corrosion condition in closed compartment compartments. See Sec. 7.2.7.

4.3 Inspection Technology Table 4-3 lists candidate areas for inspection defined in the Group C “Inspection technology”. Table 4-3 Candidate areas for inspection defined in Group C – Inspection technology. ID Code Areas to be inspected Purpose C.1 1 Details that have Confirm finding. Cause of defect may be determined. inspection findings from See Sec. 7.3.2. operation C.2 2 Areas of Validation of underwater inspection capability. See difficult/challenging Sec. 7.3.3. underwater inspection




















MANAGING RISK

4.4 Other Table 4-4 lists candidate areas for inspection defined in the Group D “Other”. Table 4-4 Candidate areas for inspection defined in Group D – Other. ID Code Areas to be inspected Purpose D.1 1 Bolts Determine how bolts and other fasteners perform over time to improve future specifications. See Sec. 7.4.2. D.2 2 Repair clamps Increase understanding of the performance of repair clamps in order to design efficient clamps in the future and to prolong the life of existing clamps. See Sec. 7.4.4. D.3 2 Marine growth Validate the recommendations given in NORSOK N003. See Sec. 7.4.5.




















MANAGING RISK

5

INFORMATION GATHERING

Information from the design phase, installation phase and operation phase of the jacket structure is important in order to select the appropriate locations for the inspection and in order to learn from the inspection. This information will determine the usefulness of follow-up analyses and tests after removal. Table 5-1 to Table 5-3 shows the type of documentation that should be available for the project. In some projects documentation can be a challenge to locate and the table therefore also list some important information that should be gathered as a minimum if the documents cannot be found. Table 5-1 Information that should be available from design and fabrication of the structure. Documentation Minimum information requested DFI resumes (including Design premises, design codes, design lives, materials modifications) selection, incidents during fabrication, CP-design report Design code, CP design zones with number of anodes and anode types, CP design life Coating specification Type of coating, coating thickness, surface preparation NDT specifications NDT methods, acceptance criteria Table 5-2 Information that should be available after transportation and installation of the structure. Documentation Minimum information requested As laid survey/inspection Condition of jacket structure when installed. Any deviations from report after installation original design? Were there any fatigue issues during transportation?




















MANAGING RISK

6

SELECTION OF AREAS

The selection of areas to inspect shall be discussed and decided for each structure brought ashore. The benefit from the inspections on the decommissioned structures may be acknowledged in other other parts of the Company than in the cessation project team, where the main focus typically has been decommissioning at low cost. In the discussion of selection of areas it is therefore crucial to bring in support from resources within technical disciplines; structural strength, inspection and materials. Resources from license partners or external consultants may also be invited. An inspection plan for decommissioned structures shall be developed either as part of the cessation project or by other parts of the organisation and thus given as input input to the cessation project. The selection of areas should comprise the following three steps: 1) Establish basis for selection of areas for inspection 2) Workshop to detail locations and specify type of inspections to be performed 3) Include requirements to inspection in the decommissioning plan

6.1 Basis for selection It is crucial to have an overview of the history of the structure as basis when selecting areas for inspection of the decommissioned structure. It would be beneficial to involve the personnel responsible for the inspection planning and people in the organization responsible for the operation/maintenance of the platform. A workshop package presenting the history of the structure should be prepared as basis for the selection of areas for inspection on the decommissioned structure. The following information should as




















MANAGING RISK

6.2 Workshop – Selection of inspections The workshop package, see Section 6.1, should form the basis for this workshop and detailed drawings of the structure shall be available. The workshop should involve personnel within the disciplines material technology, structural technology and inspection technology. The detailed locations and extend of the minimum recommended inspections, details regarding inspection and supplementary inspections should be concluded in the workshop. Table 4-1 to Table 4-4 show the minimum recommended and supplementary inspections for the structures. Minimum recommended inspections (code 1 – green) should be performed on all structures. Guidance on this is given for each ID code in Section 7. The supplementary inspections (code 2 – yellow) should be discussed in the workshop and the decision should be made based on checklists given in Appendix 2 and conclusions made during the workshop. Appendix 1 shows example of a format that may be used in the workshop. Appendix 2 presents some checklists/control questions that may be used during the workshop.

6.3 Documentation Requirements to inspection during decommissioning shall be detailed in the decommissioning plan. The decommissioning plan should as a minimum include the following: 



Detailed requirement to type and extend of inspection at specific locations of the structure (reference to areas on drawings and tag no.) All minimum recommended topics for inspection in this guideline (code 1 – green) should be covered or Company should justify why the inspection is not relevant




















MANAGING RISK

7

PREPARATIONS AND EXECUTION OF INSPECTIONS

An inspection plan for decommissioned structures shall be developed either as part of the cessation project or by other parts of the organisation and thus given as input input to the cessation project. This section provides i) motivation for the proposed inspections listed in Section 4, ii) information required prior to inspection, iii) type of inspection needed prior to offshore removal and iv) type of inspection/activity proposed at the demolition yard. Appendix 2 contains a summary table listing all potential inspections with purpose and motivation, including a check list (control questions) which can be used as a support when planning which areas to inspect and type of examination. As stated in Section 4, inspection ID’s with Code 1 are minimum recommended inspections. Inspection ID’s with Code 2 should be discussed in workshop based on the operation history of the jacket in question, and supported by the checklist in Appendix Appendix 2. The project decides if inspection/examination of these areas will provide information of general value for design of new structures and/or for life extension purpose. Inspection ID’s with Code 3 may be extensive and involve laboratory testing. Only motivation for the proposed inspections is given in Section 7. It is emphasized that a ‘no finding’ at the demolishing yard may be equally important as ‘a finding’ as regards to providing experience feedback for life extension and new designs. Similarly, a structure characterized as ‘robust’ may also be equally important to inspect as a structure with much findings during operation etc.






















MANAGING RISK

7.1 Group A – Structural Strength 7.1.1 General Onshore inspection provides a unique opportunity to increase the knowledge on how the jacket structures have behaved during decades of operation in the harsh environment of the North Sea. A general visual inspection onshore should be done prior to demolishing to inspect for visible anomalies/notabilities in order to detect any major unexpected behaviour. This initial visual inspection will give a better understanding of the systems and areas of particular interest for detailed inspections and assessment of the condition. Life extension beyond the original planned service life requires new fatigue analysis aiming for more ‘realistic’ fatigue lives. To document required fatigue life there may then be a need to use more refined fatigue analyses both with respect to wave load recipe and hotspot stress range generation. There is accordingly a need to validate/calibrate these modern fatigue analysis techniques, and closer investigation over time of decommissioned jackets is a means to accomplish this.






















MANAGING RISK

Information required prior to inspection: All weld connections with calculated fatigue utilisation ratio higher than 0.5 (as calculated according to modern analysis techniques and with DFF = 1) should be examined for fatigue cracks. Joints with lower fatigue damage may be more applicable to select in some structures. The final selection of weld connections to inspect should be based on an overall assessment of the specific structure, see Section 6. The fatigue lives shall be calculated using accurate methodology, e.g.: 

hydrodynamic coefficients dependent on the relative surface roughness (e), the Reynold’s number (R), and the Keulegan-Carpenter number (K)



hotspot stress ranges according the generalized influence function method.



Mean values in S-N curve.

For further information on fatigue analysis, see /9/.






















MANAGING RISK

Inspection on yard: 







Removal of marine growth and coating. Close visual inspection and Magnetic Particle Testing (MT) should be performed after removal of coating. Ultrasonic Testing (UT) should be performed to ensure that potential cracks starting in weld root will be detected. It may be considered to store samples for future references (e.g. qualification of NDT-methods or further investigation of the cause of the crack, remaining fatigue life etc.). It is important that such joint(s) are stored in a non-corrosive environment (i.e. indoor).

Table 9-1 lists the information that should be stored regarding this area of inspection.

7.1.3 A.2 Grout connection between leg and pile There is significant lack of data on the condition of grouted piles after installation, e.g. how well is it






















MANAGING RISK

Inspection on yard: 









Look at the grout exposed at the ends of the leg. Carefully cut out steel at various positions along the leg, leaving ‘windows’ for inspection and sample collection. Assess the quality of the grout; i.e. colour, consistency. It may be considered to store core samples for future references. It is important that such core sample(s) are stored in a dry environment. Take photos, prepare a report from the inspection and store grout samples.

Table 9-2 lists the information that should be stored regarding this area of inspection.

7.1.4 A.3 Pile/sleeve connections






















MANAGING RISK

7.1.5 A.4 Piles It is crucial that the piles maintain their integrity in case of life extension. Accordingly, the part of the pile below mudline should be investigated for any anomalies or cracks in the welds to (over time) provide increased confidence to the analyses for extreme storm and fatigue. The pile will be cut at some distance below mudline and will therefore be available for inspection at the demolition yard. As inspections of the piles are impossible offshore, it is particular important to increase the knowledge on how piles behave to provide confidence to the analysis procedures. Information from recovered piles is very valuable. Information required prior to inspection:

The following information should be reviewed prior to workshop and presented at the workshop: 

Pile drawings, design and material specifications, design premises, DFI, design reports.
























MANAGING RISK

7.1.6 A.5 Members with unintended flooding Some braces have been reported as water filled in-service, but the cause of water filling may not have been identified and explained. Inspection onshore may reveal the reason for water filling, which can be of value for similar situations for existing installations. Information required prior to inspection:
























MANAGING RISK

7.1.7 A.6 Splash zone (fatigue) These areas may be difficult to inspect without use of special equipment/climbers. It is crucial for the global integrity that main connections in these areas are intact and function according to expectations, in particular if wave-in-deck needs to be accounted for in the structural reassessments. As inspections of these areas may be difficult and infrequent due to limited access and
























MANAGING RISK

Information required prior to inspection:




Reports from inspections/repair of damaged members caused by boat impact and dropped objects. Sketches/Photos/Videos of the damage, and description of damage/dent.
























MANAGING RISK

Information required prior to inspection:


Drawings showing which members have been grouted.



Information on the purpose of grouting.
























MANAGING RISK

7.1.10 A.9 Pile to topside connection/condition of splice connections Examine damages in the pile to topsides connections. Cracks in the shim plate welds have been observed in the past. The purpose of this inspection is to confirm design assumptions. A.9 should be performed if the inspection history shows indications of cracks. It may be considered to


















































































































































































































































































































































































































































































































Report 2012_3363_Guideline for Inspection of Decommissioned Offshore Structures

Recommend Documents