FPSO Inspection

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R20821-5_UKOOA �

Lloyd’s Register of Shipping 2003

FPSO Inspection Repair & Maintenance

Study into Best Practice

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�� FPSO Inspection Repair & Maintenance

R20821-5_UKOOA Page 2 of 35 06 May 2003

5HYLVLRQ�6WDWXV�Issue Date Comment Checked Authorised

1 2 Sept, 2002 Issued for Comment RE CMcI

2 16 Sept, 2002 Steering Group comments incorporated

RE CMcI

3 26 Nov, 2002 Industry Comments incorporated RE CMcI

4 10 Jan 2003 Final Issue RE CMcI

5 06 May 2003 Minor revisions to service suppliers

RE CMcI



&RQWHQWV�Summary 4

1 Acknowledgements 6

2 Findings 7

2.1 Ramform Banff ............................................................................7

2.2 Captain........................................................................................8

2.3 Curlew .........................................................................................8

2.4 MacCulloch .................................................................................9

2.5 Schiehallion...............................................................................10

2.6 Triton .........................................................................................10

3 Discussion and Conclusions 12

3.1 General Conclusions.................................................................12

3.2 Ballast Systems, (Pipework, Tanks, Pumps and Control Systems) 15

3.3 Oil Storage System ...................................................................16

3.4 Hull ............................................................................................17

3.5 Caissons ...................................................................................18

3.6 Deck Structures, Pallets, walkways, and upper deck plating ...18

3.7 Tank Venting System, Pipework, PV Valves and Seals ...........19

3.8 Cranes.......................................................................................19

3.9 Thrusters ...................................................................................19

3.10 Swivels and Drag-Chains..........................................................19

4 Recommended Practice 20

4.1 Ballast Systems........................................................................20

4.2 Cargo Systems..........................................................................21

4.3 Hull ............................................................................................22

4.4 Caissons ...................................................................................22

4.5 Deck Structures, Pallets, walkways, and upper deck plating ...22

4.6 Tank Venting System, Pipework, PV Valves and Seals ...........22

4.7 Cranes.......................................................................................22

4.8 Swivels, Drag-Chains................................................................22

5 Suppliers and Repairers 25

Appendix A– List of Repairers 26

Appendix B– Blank Questionnaire 31



Summary

This report relates to a stud y of Inspection Repair & Maintenance (IRM) Practice on Floating Production Storage and Offtake units, (FPSOs), in service on the UK Continental Shelf.

The study, as d escribed in the invitation to tender, was intend ed to establish best practice in IRM by means of a questionnaire among FPSO operators, interviews w ith IRM personnel and through a review of literature and an Internet search. The d eliverables were to be:

1. A register of vendors, etc., to support each of the IRM categories id entified in the tend er.

2. Results of the questionnaire, in a database.

3. A discussion of the information obtained , dealing with experience on equipment, procedures and systems from agreed selected participants. This to include both the results of the interviews and data from other sources id entified in the course of the study.

4. A report, identifying for each of the strategic areas, the range of practices currently adopted, together with recommend ations on best practice to eliminate repetition of failures and re-design.

Early in the study, a number of challenges were encountered includ ing a patchy response and results of the questionnaire which, while interesting in themselves, yield ed little in the way of general trends.

The Internet search likewise revealed little that could be regarded as novel. These challenges were discussed at some length w ith the steering group.

The study set out to find an objective answer to a large and subjective question. The one common trend was that most operators regard their own IRM strategies and plans as good , even best, practice.

Almost without exception they regard the cond ition of projects as d elivered to be the root cause of failure. Neither Inspection nor maintenance featured large in the history of failures and repairs.

With these interim find ings, and consid ering the original expectation in terms of deliverables, it was agreed that the project should be re-focused on areas more likely to yield usefu l resu lts. A series of

second interviews were conducted with a number of operators. The number was not restricted : those who responded were visited and the exercise consid ered six vessels. The interviews were aimed at summarising experience and establishing key factors relating to a number of in-service failures.

A pilot study was und ertaken, commencing with BP’s Schiehallion facility. This collected data on

IRM systems. This was analysed in accordance w ith the head ings taken from the original invitation to tender document. The d ata was then compared and collated . Finally the results of the interviews were d iscussed at length, both internally and with the Steering Group.

The study concludes that most of the failures considered would have been avoid ed had closer

attention been paid to foreseeable operating cond itions at the d esign stage. Furthermore, it is optimistic, to say the least, to expect inspection and maintenance strategies, bu ilt as they are on the

assumption of competent and comprehensive design, to detect early life warranty-type defects. Finally we have conclud ed that und erstanding of risk-based I&M philosophies varies wid ely between



operators. At their worst they suggest schemes that simply accept risk, rather than those that assess and seek to mitigate or avoid risk.



1 Acknowledgements

The authors are grateful for the assistance of the study participants in preparing this report. Their openness in d ealing with matters such as system failures and lessons learned is very much appreciated . These includ ed contributions from:

Amerada Hess

Bluewater

BP Exploration

Kerr McGee

Maersk Contractors

PGS

Pierce Production Company

Shell UK

Texaco

Wood Group

Our thanks are also due to the members of the steering group, for their patience and for their invaluable contributions to a sometimes-contentious d iscussion, dealing as it d id with some d early held views on all sides.



2 Findings

2.1 Ramform Banff

Planned maintenance is applied to Safety Critical Elements (SCE’s).

The Planned Maintenance Routine (PMR) system is controlled by the STAR planned maintenance and management system. Those PMR’s relating to the SCE’s take into account the PFEER and DCR verification in add ition to Class/ IMO requirements. The initial PMR’s have been modified with operating experience to ensure all written scheme of verification (WSV’s) items are dealt with. The WSV’s now specifically refer to the related PMR’s.

The structural inspection scheme is based on the outcome of a d etailed risk assessment.

2.1.1 Repairs during 2000/2001 refit in Hamburg:-

1. Bilge keels add ed to alleviate the excessive rolling of the vessel during heavy swells. Operating experience since has shown a marked improvement in roll characteristics although the heave characteristics remain largely unchanged .

2. Substantial strengthening of process pallet main deck foundations and supports. This work was und ertaken in response to a structural motion study that showed accelerations and forces attributable to the vessel movement to be in excess of the original design limits.

3. Substantial reworking and strengthening of flare structure following fatigue failu re of surrounding structure.

4. Strengthening of KO Drum, HP, MP and Test Separators with stiffening rings to improve fatigue life in response to vessel motions in excess of those initially pred icted .

5. Extensive strengthening work on barriers and bumpers. With a congested d eck, the risk of collision by swinging loads was high and this had not been adequately addressed in the original d esign.

6. New air lock door mechanisms fitted to port sid e emergency escape tunnel to ensure positive pressure maintained . Temporary refuge outer doors planned for refurbishment to maintain integrity. Original marine HVAC system was found not to be suitable for offshore operations.

7. Repairs and modification to main turbine fuel management system. The situation previously was that, following process shutdowns, the change over from fuel gas to diesel often resulted in power outages. The change over system is now operational and power availability has been significantly improved .

8. Gradual adjustment of the process instrumentation has improved down time due to vessel movements. The bilge keels have also helped in this respect.



2.2 Captain

The PMR is risk/ corrosion based and the original concept d id consider FMEA and RCM theories. However, so far as could be seen, it appears to concentrate more on corrosion aspects. Initial frequency for the structural items is 5 years with annual examinations for a significant proportion of components. However, when examined in d etail, the situation is not as first appears. In general, the 5 yearly inspections are general examinations, while in a number of cases, close visual examination is not required until 10 years have elapsed .

Results and comments are fed back into the system to either modify the examination or to put remedial work into the planning for shut downs etc.

Maintenance sheets are produced to detail the work to be undertaken. These are well detailed as to what is required and how it is to be carried out.

Responsibility is clearly laid out in decid ing what is to be done. The overall impression is of a risk-based program with a simple functional approach.

2.2.1 Repairs

All of the repairs listed below relate to design issues, with a possible contribution of workmanship to item 5.

1. Turret – this d esign has no swivel, relying on a system of hydraulically operated grippers instead . These have all been renewed within 3 years. The turning system is d eemed to be over-stressed and not fit for purpose and is to be rep laced by a locally designed and manufactured package.

2. The hoses in the current system reach their minimum bend radius in use. This has resu lted in several failures.

3. Production Separators – Internal grids collapsed , requiring complete renewal. This was attributed to wave motions within the separators caused by the FPSO’s motion in heavy seas.

4. Sea Chests – the vessel has 11 sea chests, all of which were originally fitted with Stainless Steel grid s. This arrangement led to severe build up of crustaceans and consequent blockage: stainless steel provides an unusually conducive environment for marine life. The sea valves were also not suitable for the prolonged life expectancy in an offshore unit. The grids were renewed in carbon steel and the butterfly valves were replaced with conventional shipsid e globe valves.

5. Hull – various areas of paint coating have failed . At this stage it is unclear whether the root cause is system selection or quality of application.

2.3 Curlew

The PMRs are risk based and takes account of FMEA and RCM. The initial period icity was based on five yearly class requirements. The planned maintenance strategy utilises MAXIMO.

Maintenance Routine Sheets detail the plant or equ ipment description and each relates to a particu lar WSE & SCE, with cross-references to associated procedures and documentation. The sheets detail the equipment covered , the reference procedures, the precautions specific



to the task to be und ertaken, what is to be done and how it is to be done. PMRs typically have a hierarchy which varies from weekly checks up to 2 / 4 / 5 yearly interventions.

Defects are tracked via corrective maintenance work orders, detailing proposals for dealing with d efects and subsequent follow up activities.

2.3.1 Repairs

1. Water Ballast Tank Frames. Fatigue cracking in lower flume openings was d etected after 2-3 years of operation as FPSO. (There was no evid ence of this failure noted in 13 years as a trad ing tanker) The cracks have been d rilled & ground . Rope-access teams implemented modifications. These have been successful and are now subject to annual monitoring.

2. Caissons The unit experienced extensive noble corrosion of seawater & firewater caissons in the water ballast tanks, caused by titanium submersible pump body / caisson coating breakdown. Repairs by means of by external p lugs and re-coating were partially successful. In the worst case (SW caisson) repairs were effected by re-coating & by grouting a larger annu lar sleeve. This repair was unsuccessful. The cement leaked into and blocked base of caisson to a depth of 1-2m.

3. Steering Gear The unit suffered severe damage to the steering gear d ue to wave slam on the rud der. At the time the steering gear was hydraulically locked and the slam torque on the rudderstock caused a ruptu re and consequent d amage due to unrestrained movement. Since then permanent mechanical locks have been installed to restrain the rudder.

2.4 MacCulloch

The PMR is risk based and takes account of FMEA and RCM stud ies which were intended to refine and focus maintenance activities. The initial period icity was based on five yearly class requirements (specifically the IMO requirement). The results of initial inspections have been fed back into the system with the resu lt that repairs have been required and the frequency of inspections increased as part of the repair scenario. In 1999, the RCM stud ies and FMEA stud ies were revisited to include later OREDA statistics with a view to reducing maintenance workload & consequent backlog. Maximo provides the CMMS.

Maintenance Routine Sheets detail the plant or equ ipment description and each relates to a particu lar WSE & SCE, with cross-references to associated procedures and documentation. The sheets detail the equipment covered , the reference procedures, the precautions specific to the task to be und ertaken, what is to be done and how it is to be done. PMRs typically have a hierarchy which varies from weekly checks up to 2 / 4 / 5 yearly interventions.

Defects are tracked via corrective maintenance work orders, detailing proposals for dealing with d efects and subsequent follow up activities. The planned maintenance strategy utilises MAXIMO.

Maintenance histories are grouped by system tag numbers allowing d efect trends to be highlighted .

2.4.1 Repairs

1. Water Ballast Tank Frames Fatigue cracking in lower flume openings after 2-3 years of operation as FPSO. (No



evid ence of this failure noted in 13 years as a trad ing tanker) Cracks d rilled & ground . Modification using rope access only partially successful. Current p lan is to modify again, using a d esign recommend ed by the Tanker Co-operative Forum.

2.5 Schiehallion

PMRs are risk based and take account of FMEA and RCM. Initial period icity was based on five yearly class requ irements (specifically the IMO requirement). The results of initial inspections have been fed back into the system with the result that repairs have been required and the frequency of inspections increased as part of the repair scenario. Schiehallion uses EnGarde as the CMMS.

Maintenance Routine Sheets detail the plant or equ ipment description and each relates to a particu lar WSE & SCE, with cross-references to associated procedures and documentation. The sheets are split into two parts.

Part A details precautions specific to the task to be undertaken, part B details what is to be done and how it is to be done. It also instructs as to whom is responsible for repair method or proposals for dealing with defects and subsequent follow up activities. This is further set out in the Operations Safety Case referring to Defect Management Strategy.

2.5.1 Repairs

1. Bow Damage Heavy weather damage to vessels bow plating and internals. Plating variously indented between stiffeners with various internal brackets sprung. Repaired on location using heavier section bulb bar and larger softer brackets and strict weld ing control. Tears in way of inner d eck faired and re-weld ed .

2. Cargo Oil Tank Defects Defects found in nos. 2 & 3 starboard cargo tanks in way of transverse bulkhead lower support brackets. These are being monitored , evaluated and repaired using additional brackets and new insert p lates as required. The add itional steelwork is subject to high level of NDE and strict weld ing control. Particular emphasis was given to both strengthen and soften repair areas.

3. Water Ballast Tanks An ongoing series of cracking and cross member buckling has been found in the water ballast tanks. These are currently being assessed and a repair strategy formulated such that the d efects can be repaired on location whilst maintaining production. This will involve calculating oil and water levels in ad jacent tanks so as not to stress the bulkhead s more than is necessary. The design of the repairs remains ongoing meantime. The tanks are currently being monitored monthly.

2.6 Triton

The initial PMR’s have been revised during the last 12 months to ensure all those items required by the Written Schemes of Verification are included . Triton uses Maximo as its CMMS.

2.6.1 Repairs and Modifications

1. Additional green water protection has been added to p rotect the process equipment pallets aft of the forecastle. Further protection is p lanned to protect the knock out d rums on the forward port side. Aluminium was chosen as the construction material in order to



facilitate installation outwith the working rad ius of the installation’s main cranes. This design was stud ied to ensure that there is not an unacceptable incend ive spark risk.

2. Jib extensions to the main cranes are being planned . The rad ius of operation leaves several “dead ” areas, which can significantly increase maintenance/ change out times.

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Banff 4 4 4 4 4

Captain 4 4 4 4 4

Curlew 4 4 4

MacCulloch 4 4

Schiehallion 4 4 4

Triton 4 4 Table 1 Spread of failures/defects on selected FPSOs



3 Discussion and Conclusions

3.1 General Conclusions

3.1.1 Age of Installations and the Influence of Inspection & Maintenance

The UKCS FPSO fleet is relatively young. An important conclusion of the study therefore was that most of the failures d iscussed occurred in the early operating years, before any inspection plan could have detected signs of deterioration and before any maintenance plan could realistically be expected to anticipate the failure. Despite all attempts to establish a linkage, inspection and maintenance d id not feature large in the history of failures. Design and construction however was a dominant factor in the overwhelming majority.

This is not to say that I&M have not a crucial role to play in detecting and rectifying incipient failure. The safety of systems and equipment throughout the operational life of the installation w ill d epend ever more on the maintenance and inspection function being suitable and well implemented . However I&M strategies tend to be based on an assumption of competent d esign and construction. It should therefore come as little surprise that, with the exception of baseline inspections, they have a poor record in detecting the consequences of inadequate d esign and careless workmanship.

3.1.2 Design

If inspection and maintenance cannot prevent early life failures, what part can design and construction play? Almost all of the significant, and expensive, failures can be attributed to one or the other. The table below shows some examples.

Damage Cause

x Bow damage Inad equate structural design and inad equate consideration of environmental load ings

x Caisson Damage Material Selection

x Flare Damage Inad equate structural design and inad equate consideration of environmental load ings

x Tank defects Inad equate consid eration of environmental load ings. Errors in design process

Unsatisfactory construction techniques

Site specific load ings not anticipated in d esign process (this is perhaps the exception to the above rule since the load ings had been consid ered competently. The outcome was something of an unforeseen event.)

x Breakdown of Coating Systems

Poor application and poor selection

x Rudd er & steering gear damage

Inad equate consid eration of operating and environmental cond itions

x Swivel damage Developing technology

Table 2 Design & Const ruc t ion as Cont r ibut ory Fac t ors in Fai lures



3.1.3 Conversions

The fact that two converted vessels required structural modifications in service would ind icate that the structural load ing spectrum encountered in FPSO service d eparted to a significant d egree from that experienced during relatively long periods as trad ing tankers. This however should have been foreseen. It is acknowledged that, being permanently stationed offshore, the FPSO suffers a more onerous fatigue spectrum. For this reason, conventional advice is to improve local detail design at the conversion stage, thereby enhancing fatigue performance.

While all conversions undergo repairs in the course of conversion, many have had little or no fatigue enhancement carried out.

3.1.4 New-build

Service experience shows little to choose between the overall performance of purpose-built FPSOs and those d eveloped from speculative new-build hulls. In the case of the hull, both new and old vessels have experienced structural failures that would ind icate that site-specific environmental load ings are in excess of those p red icted by either the design or the hull strengthening report.

Operators have long been advised to apply site-specific environmental load ings d uring the design process. This is d ifficult, but not impossible, in the case of speculative bu ilt hulls; however, it was not implemented for at least one of the purpose built hulls.

Accepting that in real life there are no defect-free structures, it’ s nevertheless considered likely that conscientious application of site specific environmental load ings will serve to produce more robust and responsive d esigns.

3.1.5 Classification

Of the six vessels considered in detail, all were constructed under survey by a classification society with one being removed from class at the time of delivery. It may be worth enqu iring as to the relevance of class for FPSOs.

It’ s often stated that classification is a minimum stand ard for ship design. That vessels bu ilt to class rules suffer structural failure does not in itself und ermine the suitability of the rules. Where vessels are intend ed for particular services, add itional requirements may be adopted by, though not imposed upon, the owner. Vessels intended for operation in ice can for instance opt for one of three increasingly onerous Ice Classes. Similarly, some tanker owners have voluntarily ad opted ES (enhanced scantling) descriptive notations, ind icating that material scantlings are in excess of rule requirements. It is unclear to what extent FPSO operators elect to impose standards higher than the basic level.

It’ s also worth noting that the principal complaint about classification requirements is that they are too onerous on operating FPSOs, not too lenient.

3.1.5.1 Trends in Classification

Ship Classification is circumscribed by add itional requirements, particularly those of the International Maritime Organisation, IMO and of the International Association of Classification Societies (IACS). Both organisations represent very broad interests, includ ing owners, operators, managers, and underwriters.



It is worth noting therefore that IACS and IMO requirements in respect of hull strength have grown more onerous over the past few years, e.g.

1. While some FPSO operators pursue relatively bold inspection strategies with ever-lengthening intervals, owners of classed tankers are now required to carry out a detailed assessment of the longitud inal strength of their vessels after ten years.

2. Bulk carriers are now required to consider fore-end improvements to protect from green water. Like FPSOs, and unlike most tankers, bulk carriers have d eck-mounted equipment that is subject to damage by green water.

3. Data is available1 to ind icate that NE Atlantic maximum wave heights have increased by as much as 1.5 m over the past 20 years. Protection & Indemnity2 clubs report increased occurrence of weather damage to vessels. FPSO operators adopt novel and somewhat untried bow and hull d esigns, and suffer damage. There is a growing gap developing between shipping practice and that of FPSO operators.

Classification rules are continually being revised and developed in the face of increased technical challenges and yet there is a common complaint that they are too inflexible for operators. There is some d iscussion that that Class is an inad equate standard for FPSOs, yet the wond er is that operators find it is so d ifficult to achieve the stand ards required by class, never mind exceed ing them. Class rules certainly require to be upgrad ed but no matter which classification society is involved , they do appear to provide an opportunity for consistency and for pooling experience.

3.1.6 Risk-based Maintenance

The impression was gathered during the study that risk based maintenance was seen as an opportunity to reduce the amount of maintenance needed and with minimal effort. This is an inherently unsafe assumption.

3.1.6.1 Elements of a Risk-based Strategy

In order to have a proper risk-based system; certain elements are required , includ ing:

xA system model, line list, asset inventory, design/ construction data, etc.

xA failure analysis, strength and fatigue assessment, FMEA, etc.

xA means of ranking the highest risk items,

xA Maintenance Scheme focused on the highest risks AND the related failure modes,

xA comprehensive method for Event Id entification.

Many risk-based strategies take a very optimistic approach to the amount of effort required to carry out the above requirements. It is therefore common to find that the und erlying assessments provid e insufficient d etail as to the types of defects and the means of detecting and mitigating failures.

3.1.6.2 If not Risk-based, what?

Practice is d ivid ed between Risk-based and Rule-based . A d ifficulty of the former is that the output is sensitive to the risk assessment values and these values can be quite subjective. A

1 Cotton, Challoner & others, (1999). JERICHO, Joint Evaluation of Remote Sensing Information for Coastal and Harbour Organisations, BNSC Earth Observation LINK Project, Final Report, Southampton Oceanography Centre. 2 North of England P & I Club, November 2001



problem with the latter approach is that Rule-based strategies are, by definition, inflexible. An intermed iate strategy may offer an effective way forward .

x Initial examination and response to d evelopments can be largely d riven by generic recommendations, pooling experience and learning from a large fleet and bringing in relevant practice from outside areas, e.g. tankers, foreign FPSOs, etc.

x Subsequent tactics should be d riven more d irectly by vessel–specific experience.

x Modelling and analysis should be aimed at id entifying a rational, though not necessarily a risk basis for examination and maintenance. The former is achievable, the latter not always so.

3.2 Ballast Systems, (Pipework, Tanks, Pumps and Control Systems)

3.2.1 Pipework

Based on the data gathered , over 80% of operators use a nominal 5-year risk-based inspection cycle and utilise both non-destructive and visual examination over this period .

The remaind er use risk-based techniques to extend inspection intervals, in some cases to seven years.

3.2.2 Tanks

Over 80% of operators use a 5 year cycle to program their inspection and maintenance routines, using close visual inspections - generally involving rope access - backed up with ultrasonic thickness measurement and surface crack d etection in specific areas. Tank coating and anodes are examined generally for percentage deterioration. However over 16% of vessels are on a 7-year risk-based cycle. From this, it could be inferred that some of the tanks would not be inspected until the end of this period . While this long interval might be justified as part of an overall strategy, it offers no assurance as to the effect on ind ividual tanks of any d eterioration attributable to construction defects or to unforeseen process effects. It’ s worth bearing in mind that process cond itions on some FPSOs are quite dynamic, while the corrosion models often lag far behind . There is therefore the danger that neither inspection nor maintenance will intercep t a deterioration process in good time.

3.2.2.1 General Visual Examination (GVE) and Close Visual Inspection (CVI)

The type of inspection adopted by most respond ents is Close Visual Inspection (CVI) and not General Visual Examination (GVE). This assertion is at variance with the experience of the au thors. CVI is defined as a visual examination carried out within arms reach or the d istance at which a person would read a newspaper or book, illuminated as necessary by torch or other light source. GVE is defined as a visual examination of a space as a whole and at a d istance. While GVE will permit overall estimation of coating failure and buckling of large members, it cannot be expected to reveal crack like defects.

There appear to be a number of interpretations of CVI in use among respondents, many of them vague. This d istinction is important since both techniques have their advantages.

Consider coatings and their importance, especially in water ballast spaces. Trad itionally, vessel scantlings includ ed a margin that allowed for uncertainties and provid ed an effective corrosion allowance at the design stage. This is seldom the case now. Vessel designs are now highly optimised and generally use the minimum scantlings that the various class societies state in their rules. Under these circumstances, the coatings are now vital to the



integrity of the steelwork. GVE will often provid e ad equate assurance of the overall cond ition of coatings. By comparison, tearing of brackets and necking of stiffeners can be highly localised and w ill not be so apparent. If these defects are to be located and assessed , CVI will be required .

3.2.3 Pumps

The current practice on pumps is split evenly between a 5-year planned maintenance and inspection cycle and continuous cond ition monitoring (CM), using vibration-measuring equipment.

CM usually comprises visual examinations w ith performance monitoring and vibration monitoring of one type or another. While benchmarking for vibration monitoring may be more d ifficult on converted tankers, service experience indicates that a satisfactory degree of advance warning of failure can be achieved . There were no reported sudd en failures of systems monitored in this way.

The other general practice entails routine maintenance, dealing with time-based deterioration of the equipment.

3.2.4 Control Systems

Again a 50/ 50 split between a 5-year cycle and continuous monitoring. Ongoing system and component test routines appear to be the norm and there was little to distinguish between the chosen methods other than the d egree of d iligence applied to their implementation.

3.3 Oil Storage System

3.3.1 Pipework

The report ind icated similar use of 5 and 7-year cycles for planned maintenance and similar use of non-destructive examinations as for ballast systems. There were no reported cases of serious failures. General practice involves routine monitoring, intend ed to ensure early detection of deterioration. 50% of operators use rad iography to supplement visual and ultrasonic examinations of this p ipework, reflecting the higher level of risk perceived for these systems.

3.3.2 Tanks

Over 65% of operators use a 5 year cycle with the remaind er d ivided between 3, 7 and 10 years. Inspection methods are broad ly similar to ballast tank inspections with ultrasonic gauging of plates and examination of coatings and anode wastage.

Initial examination periods of up to 10 years are viewed with some d egree of apprehension by the authors and for two reasons. First, if tanks are not inspected fully within the first 3 to 5 years of service, no base line can be established. Second , a strategy that delays inspection of a particular tank for ten years implies a d egree of accuracy in the pred iction of the behaviour of the structure, coatings, anodes, and attachments not otherwise justified by experience.

The strategy for examining cargo tanks was quite similar to that adopted for ballast tanks. This appears strange because, while both have similar criticality in terms of hull girder strength, they often have very d ifferent susceptibilities to corrosion and they d iffer d ramatically in respect of the ease, expense, and implications of internal examinations.



Ballast tanks can generally be accessed with minimal d isruption while entry into cargo tanks entails major d isruption to, even suspension of, production operations. One might expect d ifferent approaches, recognising d ifferent threats.

3.3.2.1 Slop Tanks

Slop tanks tend to suffer accelerated deterioration and therefore would be expected to receive a greater level of inspections than cargo tanks. This d eterioration is largely attributable to the relatively high operating temperatu res, the presence of hot produced water and low oxygen levels, resu lting in instances of anaerobic su lphid e reducing bacteria (SRB). There were several known, and some suspected , instances of damage includ ing blistering and breakdown of coating and rapid wastage of steel. These problems were exacerbated in the case of FPSO conversions where, in some cases, the slop tanks received insufficient attention during the conversion to prepare them for a duty cycle more onerous than that experienced by the same tanks in conventional tanker service.

Coating systems vary from simple coal tar epoxy to high-grad e two part systems. It was not certain from the study whether the predominant factor in determining the success of the coating system was the choice of coating or the standard of application. Anecdotal evid ence ind icates that normal shipyard stand ards of preparation and application will not ensure adequate lifetime performance in such a production-critical and structurally critical area.

Slop tanks are generally d ifficult to isolate and to enter. This has d riven some operators to employ external means of examination, u tilising thickness measurement at accessible boundaries in order to interpret the cond ition of the inaccessible bound aries, i.e. measurement through the forward cargo tank bu lkhead and through the after pump room bulkhead , particularly at the bottom.

There was a certain resignation at the instances of failu re in slop tanks. The failure mechanism is well und erstood and the cure reasonably simple, however maintenance teams are hampered by poor initial d esign, first in failing to ameliorate the operating cond itions and second in provid ing inadequate facilities for isolation and repair of the tank. The knock on effect on production of entering slop tanks for either survey or repair is noted as a major problem for maintenance staff.

Cargo Oil tanks are usually partially coated with a full coating specified for the bottom 3m and top 3m.

3.3.3 Pump & Control Systems

The system employed is similar to that used on the ballast system.

3.4 Hull

External inspections of the hull, w ind and water areas, sea chests and the turret vary among the operators. 30% operate a 2½-year cycle, which equates to the mandatory International Maritime Organisations (IMO) requirement for In-Water Survey twice in 5 years. 30% inspect on an annual basis. The remaind er were a little unclear as to what they actually do.

All operators use similar inspection techniques, external examinations via an ROV, coating and anode inspections, close visual examination. The p rimary d ifference is in the frequency at which these activities take place. All operators inspect turrets at least annually, with the extent of examination largely governed by matters of ROV access. Impressed Current Protection, where fitted , is usually monitored continuously.



3.4.1 Steering Gear, Thrusters

It was surprising to find that thruster motors and steering gear should have featured in the failure records: both systems being practically redundant on all but one of the vessels considered . With maintenance and inspection budgets under constant pressure, it is d isappointing to have to commit resources to managing systems with little or no operational function.

Hydrau lic locking of steering gear is never advisable. While the relief valves will permit the rudder to give und er wave load ing, there is then no means of recovering position. The next wave can then force the tiller against its stops and can cause severe damage, even amounting to total failure of the steering gear. After the Amoco Cadiz d isaster in the 1970s, mechanical stops were required in order to restrain the rudd er in the event of hydraulic failure. Given the physical size of steering gears and the conditions und er which these stops might be called upon, these mechanical stops have provided far more psychological than physical security. It is d ifficult to conceive of a situation where it would be feasible to install these devices in the event of failure.

Much is mad e of the contention that rudd ers experience greater forces in FPSO service than in tanker service. This ignores the fact that the rudd er failures encountered have been as a resu lt of single episodes, rather than cumulative effects. Such instances of steering gear overload are an unnerving, but not entirely unusual, occurrence on ships; however they rarely resu lt in d amage to the steering gear since the system s designed to yield to the forces and then to recover.

The situation regard ing thrusters appears equivocal. Some vessels have no provision, some have provision, bu t have not fitted them, and some vessels have them fitted bu t are unable to maintain position by using thrusters alone. Two instances were d iscussed in the course of the stud y: one where a swivel bearing failed and one where it was required to examine the spider at close range. In both cases, a tug was chartered to maintain the vessel on station. Over the range of vessels considered , it is questionable whether the complication or expense of installing or maintaining thrusters is justified .

3.5 Caissons

Not all vessels have caissons: of those that have, two use a 5-year inspection cycle and one 4 years. Inspections are close visual, supp lemented by ultrasonic and ROV inspections. One operator has a programme to monitor coatings and anodes.

The only reported failure was due to a high potential d ifference between a pump body and the caisson material. This should have been anticipated at the d esign stage when selecting the materials to be used .

3.6 Deck Structures, Pallets, walkways, and upper deck plating

Inspection cycles vary with 33% of operators using a 5-year cycle, 33% a 1-year cycle and 33% using a 2 ½ to 3-year cycle. Visual examinations and coating inspections are the normal inspection methods. All operators check the upper deck thickness with ultrasonic, but the frequency varies as above.

Where cracking has been found , it has generally been attributed to inad equate d esign or installation. Although repairs are normally relatively minor in scale, they can be d ifficult to achieve with the unit in production.



3.7 Tank Venting System, Pipework, PV Valves and Seals

Inspection cycles are evenly split between 5 & 3 years. Close visual inspections and ultrasonic would appear to be the primary inspection methods. UT is used to check pipe thickness in many, but by no means all cases. One operator has a test programme for pressure testing pipework and valves.

Maintenance of seals and Pressure/ Vacuum (P/ V) Valves appears to be well addressed in all cases. Operational lessons appear to have been learned from an incid ent of tank buckling some years ago.

3.8 Cranes

Cranes represent a significant safety risk and are complex, involving significant mechanical, structural, and control and safety aspects. The maintenance and inspection arrangements were however found to be the most comprehensive and consistent. The use of a small number of specialist provid ers appears to be a critical factor. Systems, records, incident reports, lessons learned , etc., all appear to be managed competently.

The maintenance criteria include compliance with the requirements of LOLER, SI 1998/ 2307, and various classification requirements. All operators carry out rocking tests and grease analysis of slew rings as a matter of routine.

3.9 Thrusters

Three operators use a 5-year cycle; one uses a 2-½ year cycle and the remainder an annual cycle. In some cases, function tests are carried out weekly and oil analysis completed where facilities permit.

Vibration monitoring equipment is installed in some instances and ROV inspections carried out on others. Their location and relative inaccessibility normally preclud es intrusive work. Most operators have plans in place to deal with sudd en breakdown or failure, using tugs where necessary. Two operators reported instances of thruster motor failure due to thrust bearing failure. Being inactive for long periods, these motors are subject to brinelling effects. In one case the coverage of vibration monitoring was increased to includ e these motors after the event.

3.10 Swivels and Drag-Chains

The inspection of swivels and d rag chains falls into two main categories. Three operators opt for annual visual examinations, with ROVs for underwater sections. Two have a 3-year cycle and one operator has a 5-year cycle.

At least one operator has had to renew a set of swivel seals due to ingress of salt and grit particles. The exercise involved fitting a more robust system, implying that the original design may not have been equal to the service requirement.



4 Recommended Practice

4.1 Ballast Systems

4.1.1 Pipework

If completed to a comprehensive maintenance plan, the 5-year cycle would be an acceptable strategy toward ensuring early d etection of wastage and assurance that the systems remain effective.

4.1.2 Ballast Tanks

Best practice would appear to be to understand the threats to the integrity of the tank structure and the pred ictive response of the structure, then to tailor the inspection strategy to these threats. The extent of the analysis should be sufficient to identify and rank critical highly stressed areas of the structure as well as fatigue sensitive locations. The following are recommend ed:

a. Carry out a full GVE of all tanks within the first 5 years to provide a baseline for the vessel in terms of design and build quality

b. Ensure complete coating of ballast tank internals: preferably light coloured or white. This w ill provid e a high contrast background and allow rapid d etection of coating breakdown, incipient cracking, and blistering.

c. Ensure that eddy current detection is available as a first-line assessment tool. If there is no eddy current ind ication, there is seldom need for further investigation.

d . Ensure tanks are completely stripped prior to entry. This w ill speed examination of tank bottoms, particularly in way of bell mouths and mouse holes.

e. Provide good lighting, either installed or portable. This is seldom a consideration on tankers since the time element when carrying out surveys is not so critical, whereas the deferment cost of FPSO tank entry is particularly high. Bear in mind that air-d riven lanterns can be d ifficult to manoeuvre with ease and more inventive lighting solutions should be consid ered .

With the above measures, it will generally be possible to carry out a comprehensive examination and to have a high degree of confidence in the results, in terms of buckling, tearing, cracking, coating damage and anode wastage.

Thereafter examination intervals can be ad justed to take account of the tank cond itions.

4.1.3 Ballast Pumps

On the basis of the results of this stud y, either method could be viewed as good practice, best practice being very much a matter of choice for ind ividual operators. Where CM equipment is fitted however, it would be worthwhile re-visiting the scope of equipment covered by the system.



4.1.4 Ballast Controls

Observe testing and inspection routines rigorously and rectify d efects at the component level, before they escalate to system d eterioration.

4.2 Cargo Systems

4.2.1 Pipework

If completed to a comprehensive maintenance plan, the 5-year cycle would be an acceptable strategy toward ensuring early d etection of wastage and provid ing assurance that the systems remain effective. In add ition an annual external examination of the d eck lines should be carried out to detect breakdown of coating systems.

4.2.2 Cargo Tanks

Best practice would be first of all to understand the criticality of cargo tanks, both in terms of the associated safety risks and of the all-up cost of intervention, i.e. isolation, deferment manpower, preparation and reinstatement. The inspection and maintenance strategy should acknowledge these risks and costs.

The following are recommended:

a. The inspection strategy should be found ed on und erstand ing the threats to the integrity of the tank structure and on pred icting the response of the structure. The inspection plan should then be tailored to these threats. The extent of the analysis should be sufficient to id entify and rank critical areas of stress in the structure as well as fatigue sensitive locations.

b. Provide a flexible and comprehensive means of isolating, inerting, and ventilating ind ividual tanks. Trad itional tanker practice will generally be insufficient for this purpose since FPSOs suffer from d ifferent time and resource constraints in examining tanks. It should be possible, at the least, to isolate two ad jacent tanks without having to shut down production.

f. Carry out a full assessment of all tanks within the first 5 years to provide a baseline for the vessel in terms of design and build quality. This should include visual examination to an appropriate extent to establish actual cond itions at each frame interval along the cargo area. There may be a case for inferring the cond ition of a port tank from the starboard and vice versa.

g. Where possible, use high contrast coating on tank bottom and roof. This will allow rapid d etection of coating breakdown, incipient cracking and blistering.

h. Ensure that eddy current detection is available as a first-line assessment tool.

i. Ensure tanks are completely stripped prior to entry. This w ill speed examination of tank bottoms, particularly in way of bellmouths and mouse holes.

j. Ensure that tanks are clean prior to entry. This can best be achieved by retaining, maintaining and operating tank-cleaning systems. This practice has the add itional advantage of preventing the build -up of sludge, with the associated risk of SRB attack.

k. Provide good portable lighting. Tank entry duration can be shortened consid erably by this simple measure.



With the above measures, it will generally be possible to carry out a comprehensive examination and to have a high degree of confidence in the results, in terms of buckling, tearing, cracking, coating damage and anode wastage.

Thereafter examination intervals can be ad justed to take account of the tank cond itions.

4.2.3 Pumps, Controls

Recommended practice is similar to that employed on Ballast systems.

4.3 Hull

Best practice is consid ered a 2½-year ROV inspection, measuring hu ll potential. Operators should have a means of cleaning sea chests grid s and should retain blanking arrangements for sea valve maintenance. Consideration should be given to removing items during conversion which are unlikely to be used – rudders, propellers etc.

4.3.1 Steering Gear

Unless there are convincing operational reasons to retain, rudders should be removed if possible. If they are retained , best practice w ill be to keep steering motors running. The design of the steering gear allows for the effect of wave slam and will permit the rudder to both give und er wave load ing and to recover after impact.

4.4 Caissons

A program of thickness d etermination, using variations on riser inspection tools, can provide early detection of wastage. Wastage rates can however be excep tionally high and the cost of intervention means that a materials review would be recommend ed , taking appropriate action in respect of material change out insulation, shield ing or other preventive measures.

4.5 Deck Structures, Pallets, walkways, and upper deck plating

GVE is usually adequate, w ith supplementary Ultrasonic Testing (UT) of main deck plating.

4.6 Tank Venting System, Pipework, PV Valves and Seals

Conventional techniques for examining and maintaining these systems appear ad equate. It is important however to continue to stress the criticality of these systems in relation to hull strength, fire and explosion.

4.7 Cranes

Total Vendor Maintenance programs are recommended . Service experience here und erlines the benefits of employing experts with the associated critical mass in investment in technology and training.

4.8 Swivels, Drag-Chains

While swivel seal and bearing failures have been encountered , there was little information available from which to d raw generic lessons. As both systems may be consid ered to be based on proprietary d esigns, manufacturer advice would appear to constitu te best practice at present.



Given the severe consequences of seal failure, it is recommend ed that the criticality of seal monitoring and protection systems — header tanks, pressurisation systems, etc. — be reviewed .



This table considers six vessels. The percentage figures relate to the number of vessels, not the number of owners/operators

The table above gives an ind ication of the range of generic techniques applied to IRM on FPSOs. The conclusion is that, while there are some outlying cases, operators are relatively consistent in their practices. The table also ind icates that general practice remains relatively conservative d espite the apparent novelty of some risk-based strategies. This would appear to leave ample scope for development and improvement.

Ave

rage

Insp

ectio

n In

terv

al (m

onth

s)

Gen

eral

Exa

min

atio

n

Gen

eral

Vis

ual

Clo

se V

isua

l

Ultr

ason

ic E

xam

inat

ion

Rad

iogr

aphy

MP

I

RO

V E

xam

inat

ion

Coa

ting

Exa

min

atio

n

Ano

de In

spec

tion

Vib

r M

onito

ring

Sys

tem

Tes

t

Roc

king

Tes

t

Gre

ase

Ana

lysi

s

System Component

60

GRP 48 67%

Cunifer 48 17%

Carbon Steel 54 100% 83% 33% 17%

Tanks WB Tanks 54 17% 83% 100% 83% 100% 100% 17%WB Tanks 120 17%

Forepeak 54 17% 83% 100% 83% 100% 100% 17%

Forepeak 120 17%

Afterpeak 54 17% 83% 100% 83% 100% 100% 17%

Afterpeak 120 17%Pumps 25 100% 100%Control Systems 34 100% 100%

Pipework Carbon Steel 54 100% 83% 50%

Cargo Tanks 53 17% 83% 83% 83% 100%

Cargo Tanks 120 17%

Slops Tanks 43 17% 83% 83% 83% 100%Slops Tanks 120 17%

Pumps 25 83% 83%

Control Systems 27 100% 100%

Tanks & Above Water Continuous Survey Hull 72

Subsea 30

External Sea Chests 33 83% 83% 100% 100% 100%Internal Sea Chests 45

Turret 27 100% 83% 100% 50%

Cathodic Protection 30 83% 83%

Wind & Water Area 25 100% 17% 100%

Caissons 52 33% 33% 33% 17% 33% 17%Pallets 33 100% 83% 17%Walkways 33 100% 17%

Deck Plating 38 100% 100% 17%

Tank Venting System 19

Pipework 50 100% 83% 83%

P/V Valves 34 100% 17%Seals 26 100% 17%

42 100% 33% 33%

Grease Sampling 3 100%

Rocking Test 6 100%

Thrusters 33 67% 83% 17% 17% 33% 17%

21 67%Swivels - Leak recuperation 1 33% 33% 33%

Swivels - Instrumentation 54 33% 33%

Swivel Stack (mechanical) 60 33% 33%Chains / stoppers / anchors 33 33% 33% 33%

Pipework

Tanks

External

Cranes

Ballast Water System

Swivels & Drag Chains

Oil Storage System

Hull

Deck structures

Table 3 Application of Maintenance and Inspection Techniques on FPSOs



5 Suppliers and Repairers

Append ix A contains a list of IRM providers. The list is not extensive bu t it serves to illustrate a range of service organisations w ith d irect experience of in-service repair to FPSOs.



Appendix A– List of Repairers

List of Repair Organisations

Study into Best Practice

Atlas Winch & Hoist Services Knocklee Biggar Lanarkshire +44 (0) 1899 221577 +44 (0) 1899 221515 Balmoral Balmoral Park Loirston Aberdeen AB12 3GY +44 (0) 1224 859059 +44 (0) 1224 859059 G. J Wortelboer jr BV PO Box 5003 NL - 3008 AA Rotterdam +31 10 429 2222 +31 10 429 6459 Lloyds Beal Anchor House Dumballs Road Cardiff CF10 5TX +44 (0) 2920 231296 +44 (0) 2920 342719 Vlaardingen Oost Anchor & Chain PO Box 47 3130 AA Vlaardingen The Netherlands +31 (0) 10 434 2744 Cranes Offshore Crane Engineering Ltd Burnside Drive Farburn Industrial Estate, Dyce Aberdeen AB21 0HW

+44 (0) 1224 797300 +44 (0) 1224 797301 Sparrows Offshore Services Ltd

Denmore Road Bridge of Don Aberdeen AB23 8JW +44 (0) 1224 704868

Pipework & General Engineering 3 Plus Engineering Ltd Badentoy Road, Badentoy Park Portlethen Aberdeen AB12 4YA +44 (0) 1224 782211 +44 (0) 1224 782266

ABB Offshore Systems Ltd Hareness Road Altens Aberdeen AB12 3LE +44 (0) 1224 872211 +44 (0) 1224 894840

Aberdeen Valve & Fitting Co Ltd Unit 1, Stoneywood Park Stoneywood Road Aberdeen AB21 7DZ +44 (0) 1224 722468 +44 (0) 1224 723009

Agra (Precision Engineering) Co Ltd 15 Ure Street Dundee DD1 5JD +44 (0) 1382 229333 +44 (0) 1382 226918 Air Power & Hydraulics Ltd 15 Watt Road Hillington Estate +44 (0) 141 810 4511 +44 (0) 141 3825


Glasgow G52 4PQ

AJT Engineering Ltd

Craigshaw Crescent West Tullos Industrial Estate Aberdeen AB12 3TB

+44 (0) 1224 871791

+44 (0) 1224 890251

Alfa Laval Ltd., Oilfield Division

6 Wellheads Road Farburn Industrial Estate Aberdeen AB21 7HG

+44 (0) 1224 424300

+44 (0) 1224 725213

Caledonian Petroleum Services Ltd

Unit 4 Howe Moss Avenue Kirkhill Industrial Estate Dyce Aberdeen AB21 0GP

+44 (0) 1224 725345 +44 (0) 1224

725406

Grayloc Hydropark Tern Place, Denmore Road Aberdeen AB23 8JX

+44 (0) 1224 222790

+44 (0) 1224 222780

Hydra Tight Ltd Howe Moss Crescent Kirkhill Industrial Estate Aberdeen AB21 0GN

+44 (0) 1224 770739

+44 (0) 1224 724175

Mach-Ten Offshore Ltd

Pitmedden Road Dyce Aberdeen AB21 0DP

+44 (0) 1224 773565

+44 (0) 1224 773568

Micron Eagle Hydraulics Ltd

Blackburn Industrial Estate Kinellar Aberdeen AB21 0RK

+44 (0) 1224 790970

+44 (0) 1224 790970

S&D Fabrications Ltd

Greenbank Crescent East Tullos Aberdeen AB12 3BG

+44 (0) 1224 895564

+44 (0) 1224 899065

Schoolhill Hydraulic Engineering Co Ltd

3 Greenbank Place East Tullos Aberdeen AB12 3RJ

+44 (0) 1224 871086

+44 (0) 1224 897135

Transmark Valves Ltd

Anglian Lane Bury St Edmunds Suffolk IP32 6SR

+44 (0) 1284 701206

+44 (0) 1284 705596

Whittaker Engineering

Hindwells Stonehaven Kincardineshire AB39 3UT

+44 (0) 1569 762018

+44 (0) 1569 766701


Pumps

Centrilift Howe Moss Drive Kirkhill Industrial Estate Aberdeen AB21 0ES

+44 (0) 1224 772233

+44 (0) 1224 771021

Buchan Technical Services

Unit 1, The Meadows Oldmeldrum Aberdeenshire AB51 0EZ

+44 (0) 1651 872130

+44 (0) 1651 872133

Sulzer Turbo Ltd CH - 8023 Zurich Switzerland

+41 / 1-278 22 11 +41 / 1- 278 29 89

Weir Pumps Ltd 149 Newlands Road Cathcart Glasgow G44 4EX

+44 (0) 141 637 7141

+44 (0) 141 637 7358

Ship–Repairers & Marine Engineers Aker McNulty Ltd Commercial Road

South Shields Tyne & Wear NE33 1RZ

+44 (0) 191 401 5800

+44 (0) 191 401 5802

Blohm & Voss Repair Gmbh

PO Box 10 05 26 D - 20004 Hamburg

+49 (40) 31 19 - 8000

+49 (40) 31 19-3305

Gusto Engineering

PO Box 11.3100 AA Schiedam The Netherlands

+31 10 10 2466800

+31 10 2466900

Izar P de la Castellana, 55 28046 Madrid

+34 91 335 8467 +34 91 335 8638

Motherwell Bridge Group

PO Box 4 Logans Road Motherwell ML1 3NP

+44 (0) 1698 266111

+44 (0) 1697 269774

Verolme Botlek bv

PO Box 1001 3180 AA Rozenburg The Netherlands

+31 181 234300 +31 181 234346

NOORDHOEK Offshore B.V.

Industrieweg 23-29 4301 RS Zierikzeehe Netherlands P.O. Box 200 4300 AE Zierikzee The Netherlands

+31(0)111 456000 +31(0)111 456001 [email protected]

Thrusters / Electrical Balfour Kilpatrick Ltd

Glasgow Road Deanside Renfrew PA4 8XZ

+44 (0) 141 885 4321

+44 (0) 141 0717

Brush Electrical Machines Ltd

PO Box 18 Loughborough Leics.

+44 (0) 1509 611511 +44 (0) 1509 610440


LE11 1HJ

Deebridge Electrical Engineers Ltd

Craigshaw Road West Tullos Industrial Estate, Tullos Aberdeen AB12 3AR

+44 (0) 1224 871548 +44 (0) 1224 899910

Dowding & Mills (Scotland) Ltd

Lochlands Industrial Estate Larbert Central FK5 3NS

+44 (0) 1324 556511 +44 (0) 1324 552830

Kongsberg Simrad

Campus 1 Science & Technology Park Bridge of Don Aberdeen AB22 8GT

+44 (0) 1224 226500 +44 (0) 1224 226501

Stephenson Marine

Wrecclesham Farnham Surrey GU10 4JS

+44 (0) 1252 714199 +44 (0) 1252 733662

Inspection/Repair General CAN Offshore Hareness Road

Altens Aberdeen AB12 3LE

+44 (0) 1224 870100 +44 (0) 12224 870101

Also offer riser inspection tool for caissons, as well as risers

CORE Technical Services

Howe Moss Drive Kirkhill Industrial Estate Dyce Aberdeen AB21 0GL

+44 (0) 1224 771118 +44 (0) 1224 771112

E M & I Marine Ltd

Wrecclesham Farburn Terrace Dyce Aberdeen

+44 (0) 1224 771077 +44 (0) 1224 771049

Hi-Rope Unit 8 Woodlands Drive Kirkhill Industrial Estate Dyce Aberdeen AB21 0GW

+44 (0) 1224 772161 +44 (0) 1224 772156

TRAC International Ltd

Unit 2 Howe Moss Drive Kirkhill Industrial Estate Dyce Aberdeen

+44 (0) 1224 725800 +44 (0) 1224 725801

Appendix B– Blank Questionnaire

FPSO Name

Age (years from New Build/Conversion) Build Conversion

Duty Holder

Owner

Operator

License Holder

Field Name

Location (Block No.)

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�� FPSO IRM Questionnaire�

How was the maintenance and inspection regime derived (tick

more than one box if applicable)?

System Can

maintenance

and inspection

routines be

made available

(yes / no)

Manufacturers

Recommendations

Operational

Experience

Risk -Based Class

Require

ments

Major failures / repairs

encountered (yes / no)

Note : for each major

failure / repair please

complete the

failure/repair

questionnaire

Do you

uses Failure

Mode and

Effect

Analysis

(FMEA) in

your

maintenanc

e strategy

Do you use

Reliability

Centred

Maintenanc

e (RCM) in

your

maintenanc

e strategy

Do you use

condition

monitoring in your

maintenance

strategy

1. Thrusters

2. Ballast & Cargo Systems

V Pipework

V Pumps

V Control Systems

3. Tank Venting Systems

4. Swivels & drag chains

5. Hull – External (including sea-chests and discharges)

6. Hull – Internal (Tanks, Frames, Stringers, etc.)

7. Deck Structures (including protection against green water damage)

8. Caisson systems

9. Cranes

Maint enanc e Syst em Who manages maintenance for the installation

Who manages repairs for the installation

List any significant changes to your Maintenance Strategy, if any

Note – 1 – 9 relates to the systems listed on Page 2 1 2 3 4 5 6 7 8 9

Did you originally use vendors/OEM’s to service the systems, i.e. during warranty period

Do you still use vendors to service the system If not, why not

Do you use campaign maintenance squads Where

Do you have Health-Care contracts in place for any of the systems

Why Have you changed your vendor/campaign strategy Why

Do you have a Risk-Based Inspection (RBI) Philosophy If so, what is it based on

Who manages inspection

In respect of the systems below, do the following factors influence Reliability, Availability, Maintainability and Operability

a Weather

b Vessel Motion

c Vibration

d Access

e Design

f Material

Selection / Corrosion

g Others (Please

Specify)

1. Thrusters

2. Hull Internal

3. Cargo & Ballast Systems

4. Tank Venting

5. Swivels, Drag Chains

6. Hull External

7. Deck Structures

8. Caissons

9. Cranes

Comments

Note The matrix above should be filled in with respect to the effect that the items in the horizontal row (a to g) have on the items in the vertical column (1 to 9).

Availability (Total Hrs in Period – (Scheduled Downtime + Unscheduled Downtime))/ Total Hrs in Period

Reliability (Total Hrs in Period – Unscheduled Downtime)/ Total Hrs in Period

Operability The degree to which the operation of the system is influenced by the factor, e.g. weather, vibration, etc.

Maintainability The degree to which the ease of maintenance of the system is influenced by the factor, e.g. weather, vibration, etc.

Fai lures / Repairs 1 In respec t of syst em fa i lures in t he areas of in t erest on Page 2 above…

Identify the component that failed

What was the root cause

Safety or Environmental Incident

Lost Production

- number days lost production

High Repair Cost

What was the consequence of failure (tick more than one box if applicable)

- cost of repair

Like for like Was a Repair/Reinstatement carried out… (provide details of the repair on separate sheet)

Re-design

Could the failure have been prevented by Maintenance or foreseen by Inspection

Peculiar to FPSOs Was the failure

Generic to Oil & Gas installations

Verification and Classification In the course of the repair/reinstatement, were you aware of any conflict between ……

Verification & North Sea Practice

Was the repair successful

Who carried out the repair

Has the failure driven a change to your Inspection or Maintenance practice

What inspection and maintenance techniques have you adopted to monitor / prevent the failure from recurring

Vendor/OEM

Main contractor

Specialist Contractor

Were repairs/reinstatement carried out by

Local Vendor/Non-Specialist Contractor

What recommendations did you feed back into design to eliminate these failures

Have you an established “Lessons Learned/ Good Engineering Practice” system to capture this information

Is this information available Internally

Is this information available Externally

Documents

FPSO Inspection