OP033FPSO Repaire and Maintenance

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R20821-5_UKOOA Lloyd’s Register of Shipping 2003

FPSO Inspection Repair &

Maintenance

Study into Best Practice



FPSO Inspection Repair & Maintenance

R20821-5_UKOOA Page 2 of 35 06 May 2003

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Issue Date Comment Checked Authorised

1 2 Sept, 2002 Issued for Comment RE CMcI

2 16 Sept, 2002 Steering Group commentsincorporated

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 servicesuppliers

RE CMcI





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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.................................................................123.2 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 r elates to a stud y of Inspection Repair & Maintenan ce (IRM) Practice on Floating

Produ ction Storage and Offtake units, (FPSOs), in service on the UK Contin ental Shelf.

The study, as d escribed in th e invitation to tend er, was intend ed to establish best practice in IRM by

means of a qu estionnaire among FPSO operators, interviews w ith IRM p ersonnel and throu gh a

review of literature and an Internet search. The deliverables were to be:

1. A register of vendor s, etc., to supp ort each of the IRM categories identified in the tend er.

2. Results of the questionn aire, in a d atabase.

3. A discussion of the information obtained, dealing with experience on equipment, procedures and

systems from agreed selected pa rticipants. This to include both the results of the interviews and

data from oth er sources iden tified in th e course of the stud y.

4. A report , identifying for each of the strategic areas, the range of practices currently ad opted ,

together w ith recommen da tions on best practice to eliminate rep etition of failures and re-design.

Early in the stud y, a num ber of challenges were encountered including a patchy response and results

of the questionnaire w hich, while interesting in them selves, yielded little in the way of general trend s.

The Intern et search likewise revealed little that could be regard ed 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 su bjective question. The one comm on

trend w as that most operators regard their own IRM strategies and plans as good, even best, practice.Almost w ithout exception they regard the cond ition of projects as delivered to be the root cau se of

failure. Neith er Inspection nor m aintenance featured large in the history of failur es and repairs.

With these interim findings , and considering th e original expectation in terms of deliverables, it wa s

agreed th at the project should be re-focused on areas mor e likely to yield useful results. A series of

second interviews were conducted w ith a num ber of operators. The number w as not restricted: those

wh o respond ed w ere visited and the exercise considered six vessels. The interviews were aimed at

sum mar ising experience and establishing key factors relating to a num ber of in-service failures.

A pilot stud y was u nd ertaken, commen cing with BP’s Schiehallion facility. This collected d ata on

IRM systems. This was analysed in accordance with t he head ings taken from th e original invitation to

tend er document . The da ta was then comp ared and collated. Finally the results of the interviewswere discussed at length, both internally and with the Steering Group.

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

attention been paid to foreseeable operating cond itions at the design stage. Furtherm ore, it is

optimistic, to say the least, to expect inspection and ma intenance strategies, built as they are on the

assumption of competent and comprehensive design, to detect early life warranty-type defects.

Finally we have concluded that understanding of risk-based I&M philosophies varies widely 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 author s are grateful for the assistance of the stud y participants in p reparin g this report.

Their openness in dealing w ith matters su ch as system failures and lessons learned is very

mu ch app reciated. These included contributions from :

Amerada Hess

Bluewater

BP Exploration

Kerr McGee

Maersk Contractors

PGS

Pierce Production Company

Shell UK

Texaco

Wood Group

Our th anks are also du e to the members of the steering grou p, for their patience and for

their invaluable contributions to a sometim es-contentiou s discussion, dealing as it did w ith

some dear ly held views on all sides.





2 Findings

2.1 Ramform Banff

Planned mainten ance is ap plied t o Safety Critical Elemen ts (SCE’s).

The Planned Maintenan ce Routine (PMR) system is controlled by the STAR plann ed

maint enance and m anagem ent system. Those PMR’s relating to the SCE’s take into account

the PFEER and DCR verification in add ition to Class/ IMO requirem ents. The initial PMR’s

have been m odified with operating experience to ensu re all written scheme of verification

(WSV’s) items are dealt with. The WSV’s now specifically refer to the related PMR’s.

The structur al inspection schem e is based on t he outcom e of a d etailed r isk assessment.

2.1.1 Repairs during 2000/2001 refit in Hamburg:-1. Bilge keels ad ded to alleviate the excessive rolling of the vessel du ring h eavy sw ells.

Operat ing experience since has show n a mar ked imp rovem ent in roll characteristics

although the heave characteristics remain largely unchanged.

2. Substantial strengthening of process pallet main deck foundations and supports. This

work w as und ertaken in response to a structural motion study th at showed accelerations

and forces attribu table to the vessel movem ent to be in excess of the original design

limits.

3. Substan tial reworking and strength ening of flare structure following fatigue failure of

surround ing structure.

4. Strength ening of KO Drum , HP, MP and Test Separa tors with stiffening rings to imp rovefatigue life in resp onse to v essel motions in excess of those initially pred icted.

5. Extensive strengthening w ork on barriers and bu mp ers. With a congested d eck, the risk

of collision by swinging loads w as high and this had n ot been adequately add ressed in

the original design.

6. New air lock door mechanisms fitted to port side emergency escape tunnel to ensure

positive pr essure m aintained. Temporary r efuge outer doors p lanned for refurbishment

to maintain integrity. Original mar ine HVAC system was found not to be suitable for

offshore opera tions.

7. Repairs and modification to main turbine fuel management system. The situation

previously w as that, following p rocess shutd own s, the chang e over from fuel gas todiesel often resulted in p ower ou tages. The change over system is now op erational and

pow er availability has been significantly imp roved .

8. Gradual adjustment of the process instrumentation has improved d own time d ue to

vessel movement s. The bilge keels have also helped in this respect.





2.2 Captain

The PMR is risk/ corrosion based and t he original concept did consid er FMEA and RCM

theories. How ever, so far as could b e seen, it appears to concentrate more on corrosion

aspects. Initial frequ ency for the stru ctural items is 5 years w ith annu al examina tions for a

significant prop ortion of compon ents. How ever, wh en examin ed in detail, the situation is

not as first app ears. In general, the 5 yearly inspections are general examinations, wh ile in a

nu mber of cases, close visual examination is not requ ired u ntil 10 years have elapsed .

Results and comm ents are fed back into the system to either mod ify the examination or to

put r emedial work into the planning for shut dow ns etc.

Maintenance sheets are prod uced to detail the work to be und ertaken. These are well

detailed as to what is required and how it is to be carried out.

Responsibility is clearly laid out in d eciding wh at is to be done. The overall imp ression is of

a risk-based program with a simple functional appr oach.

2.2.1 Repairs

All of the repa irs listed below r elate to design issues, with a possible contribu tion of

workm anship to item 5.

1. Turret – this d esign has no swivel, relying on a system of hydrau lically operated grip pers

instead. These have all been renew ed within 3 years. The turning system is deemed to be

over-stressed and n ot fit for pur pose and is to be replaced by a locally designed and

manu factured package.

2. The hoses in the current system r each their minimum bend rad ius in use. This has

resulted in several failur es.

3. Produ ction Separa tors – Internal grids collapsed , requiring comp lete renew al. This wa s

attributed to wave motions within th e 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 w ith Stainless

Steel grids. This arran gemen t led to severe build up of crustaceans and consequent

blockage: stainless steel pro vides an u nu sually condu cive environment for m arine life.

The sea valves were also not su itable for the p rolonged life expectancy in an offshore

unit. The grids w ere renewed in carbon steel and th e butterfly valves were replaced w ith

conventional shipsid e globe valves.

5. Hu ll – various areas of paint coating have failed. At this stage it is unclear wheth er the

root cause is system selection or q uality of app lication.

2.3 Curlew

The PMRs are risk based an d tak es account of FMEA and RCM. The initial period icity was

based on five yearly class requiremen ts. The plann ed main tenance strategy utilises

MAXIMO.

Maintenan ce Routine Sheets detail the plant or equ ipm ent description and each relates to a

par ticular WSE & SCE, with cross-references to associated p rocedur es and docu ment ation.

The sheets detail the equipm ent covered, the reference procedur es, the precautions specific





to the task to be under taken, wh at is to be done and how it is to be do ne. PMRs typ ically

have a hierarchy w hich varies from w eekly checks up t o 2 / 4 / 5 yearly interventions.

Defects are tracked via corrective maintenan ce work ord ers, detailing prop osals for d ealing

with defects and subsequent follow up activities.

2.3.1 Repairs

1. Water Ballast Tank Frames.

Fatigue cracking in low er flume op enings w as detected a fter 2-3 years of operation as

FPSO. (There was no evidence of this failure noted in 13 years as a trading tan ker) The

cracks have been drilled & groun d. Rope-access teams imp lemented m odifications.

These have been successful and are now su bject to annu al monitoring.

2. Caissons

The unit experienced extensive noble corrosion of seawater & firewater caissons in the

water ballast tanks, caused by titanium su bmersible pum p bod y / caisson coating

breakdow n. Repairs by mean s of by external plugs and r e-coating were partially

successful. In the w orst case (SW caisson) repairs w ere effected by re-coating & by

grouting a larger annu lar sleeve. This rep air was unsu ccessful. The cement leaked into

and blocked base of caisson to a d epth of 1-2m.

3. Steering Gear

The unit suffered severe damage to the steering gear due to wave slam on the rud der. At

the time the steering gear w as hydrau lically locked a nd the slam torque on the

rudd erstock caused a rup ture and consequent damage du e to unr estrained m ovement.

Since then p erman ent mechanical locks have been installed to restrain the rud der.

2.4 MacCulloch

The PMR is risk based and takes accoun t of FMEA and RCM studies w hich were intend ed

to refine and focus mainten ance activities. The initial period icity was based on five yearlyclass requirem ents (specifically the IMO requ irement). The results of initial inspections

have been fed back into the system w ith the result that repairs have been required and th e

frequency of inspections increased as p art of the repair scenario. In 1999, the RCM studies

and FMEA stud ies were revisited to includ e later OREDA statistics with a view to red ucing

maint enance workload & consequen t backlog. Maximo provid es the CMMS.


par ticular WSE & SCE, with cross-references to associated p rocedur es and d ocum entation.

The sheets detail the equipm ent covered, the reference procedur es, the precautions specific

to the task to be under taken, wh at is to be done and how it is to be don e. PMRs typ ically

have a hierarchy w hich varies from w eekly checks up t o 2 / 4 / 5 yearly interventions.

Defects are tracked via corrective maintenan ce work ord ers, detailing prop osals for d ealing

with d efects and su bsequen t follow up activities. The planned m aintenan ce strategy utilises

MAXIMO.

Maintenance histories are group ed by system tag nu mbers allowing defect trends to be

highlighted.

2.4.1 Repairs

1. Water Ballast Tank Frames

Fatigue cracking in lower flum e openings after 2-3 years of operation as FPSO. (No





evidence of this failure noted in 13 years as a trading tan ker) Cracks drilled & groun d.

Modification using rop e access only partially successful. Curr ent plan is to mod ify again,

using a d esign recommend ed by th e 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 requirem ents (specifically the IMO requ irement). The results of initial

inspections have been fed back into the system w ith the result that rep airs have been

required and the frequency of inspections increased as part of the repair scenario.

Schiehallion uses EnGard e as the CMMS.


par ticular WSE & SCE, with cross-references to associated p rocedur es and d ocum entation.

The sheets are split into two p arts.

Part A d etails pr ecautions specific to the task to be un dertak en, part B details what is to be

don e and how it is to be done. It also instructs as to wh om is responsible for repair method

or pr oposals for dealing with d efects and su bsequen t follow u p activities. This is furth er set

out in th e Operation s Safety Case referring to Defect Managem ent Strategy.

2.5.1 Repairs

1. Bow Damage

Heavy w eather dam age to vessels bow plating and internals. Plating variously indented

between stiffeners with various intern al brackets spru ng. Repaired on location usin g

heavier section bulb bar a nd larger softer brackets and strict welding control.

Tears in w ay of inner d eck faired and re-welded .

2. Cargo Oil Tank Defects

Defects foun d in nos. 2 & 3 starboard cargo tanks in w ay of transverse bulkh ead low er

support brackets. These are being mon itored, evaluated and repaired using ad ditionalbrackets and new insert plates as required. The add itional steelwork is subject to high

level of NDE and strict w elding control. Particular em pha sis was given to both

strengthen and soften repair areas.

3. Water Ballast Tank s

An ongoing series of cracking and cross mem ber buckling has been found in th e water

ballast tanks. These are currently being assessed and a repair strategy formu lated such

that the d efects can be repa ired on location whilst maintaining p rod uction. This will

involve calculating oil and w ater levels in ad jacent tanks so as not to stress the bulkh eads

more tha n is necessary. The design of the repairs remains ongo ing meant ime. The tanks

are currently being m onitored month ly.

2.6 Triton The initial PMR’s have been revised d urin g the last 12 months to ensur e all those items

required by the Written Schemes of Verification are includ ed. Triton uses Maximo as its

CMMS.

2.6.1 Repairs and Modifications

1. Add itional green water p rotection has been add ed to p rotect the p rocess equipment

pallets aft of the forecastle. Further p rotection is plann ed to prot ect the knock out d rum s

on the forward port side. Aluminium was chosen as the construction material in ord er to





facilitate installation ou twith the working ra dius of th e installation’s main cran es. This

design was stud ied to ensure that there is not an u nacceptable incendive spark risk.

2. Jib extensions to the m ain cranes are being plann ed. The radiu s of operation leaves

several “dead” areas, which can significantly increase mainten ance/ change out times.

B a l l a s t P i p e w o r k

B a l l a s t T a n k s

B a l l a s t P u m p s

B a l l a s t C o n t r o l S y s t e m s

O i l S t o r a g e S y s t e m P i p e w o r k

O i l S t o r a g e S y s t e m T a n k s

O i l S t o r a g e S y s t e m P u m p s

O i l S t o r a g e S y s t e m C o n t r o l S

y s t e m s

H u l l T a n k s & A b o v e W a t e r

H u l l E x t e r n a l

H u l l I n t e r n a l

C a i s s o n s

D e c k s t r u c t u r e s P a l l e t s

D e c k s t r u c t u r e s W a l k w a y s

D e c k s t r u c t u r e s D e c k P l a t i n g

T a n k V e n t i n g S y s t e m P i p e w o

r k

P / V V a l v e s

S e a l s

C r a n e s

T h r u s t e r s

S w i v e l s & D r a g C h a i n s

Banff

Captain

Curlew

MacCulloch

Schiehallion

Triton

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 youn g. An imp ortant conclusion of the stud y therefore

was th at most of the failures discussed occur red in th e early operating year s, before any

inspection plan could have detected signs of deterioration and before any maintenance plan

could realistically be expected to an ticipat e the failur e. Despite all attempts to establish a

linkage, inspection and maint enance did not featu re large in the history of failures. Design

and construction how ever was a d ominant factor in the overw helming majority.

This is not to say that I&M have n ot a crucial role to play in detecting an d r ectifying

incipient failure. The safety of systems and equ ipm ent throu ghou t the operational life of

the installation will depend ever more on the maintenance and inspection function beingsuitable and well implemen ted. How ever I&M strategies tend to be based on an

assum ption of comp etent design and constru ction. It shou ld therefore come as little

surp rise that, with th e exception of baseline inspections, they have a p oor record in

detecting the consequences of inadequate design and careless workmanship.

3.1.2 Design

If inspection and m aintenan ce cannot pr event early life failures, what p art 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 examp les.

Damage Cause

x Bow d amage Inadequate structural design and inadequate consideration of environmental loadings

x Caisson Dam age Material Selection

x Flare Damage Inadequate structural design and inadequate consideration of

environmental loadings

x Tank d efects Inadequ ate consider ation of environm ental loadings. Errors in

design process

Unsatisfactory constru ction techniqu es

Site specific loadings not anticipated in d esign pro cess (this is

perh aps the exception to the above rule since the loadings had

been consid ered competent ly. The outcome was something of an

unforeseen event.)

x Breakdown of

Coating Systems

Poor app lication and poor selection

x Rudder & steering

gear dam age

Inadequate consideration of operating and environmental

conditions

x Swivel dam age Developing technology

Table 2 Design & Construct ion as Contr ibu tory Factors in Fa i lu res





3.1.3 Conversions

The fact that two converted vessels required structu ral mod ifications in service would

indicate that the structural loading spectrum encountered in FPSO service departed to a

significant degree from that experienced during relatively long periods as trading tankers.

This how ever should have been foreseen. It is acknow ledged that , being perman ently

stationed offshore, the FPSO suffers a more onerous fatigue spectrum . For this reason,

conventional adv ice is to improv e local detail design at the conversion stage, thereby

enhancing fatigue performance.

While all conversions un dergo r epairs in the course of conversion, man y have ha d little or

no fatigue enhancement carried out.

3.1.4 New-build

Service experience show s little to choose betw een the overall per formance of pu rpose-built

FPSOs and th ose developed from speculative new-build h ulls. In the case of the hull, both

new and old vessels have experienced structural failures that would indicate that site-

specific environm ental loadings are in excess of those predicted by either the d esign or thehull strengthening report.

Operators have long been advised to apply site-specific environmental loadings during the

design p rocess. This is difficult, but not imp ossible, in the case of speculative built hulls;

however, it was not imp lemented for at least one of the pu rpose built hulls.

Accepting t hat in r eal life there are no defect-free structu res, it’s nevertheless considered

likely tha t conscientious app lication of site specific environmental loadings w ill serve to

prod uce more robust and r esponsive designs.

3.1.5 Classification

Of the six vessels considered in detail, all were constructed u nd er surv ey by a classification

society w ith one being removed from class at the time of delivery. It may be w orthenqu iring as to the r elevance of class for FPSOs.

It’s often stated th at classification is a minimu m stand ard for ship d esign. That vessels built

to class rules suffer structura l failure does not in itself und ermine the su itability of the rules.

Where vessels are intended for particular services, additional requirements may be adopted

by, though not imp osed up on, the owner. Vessels intend ed for operation in ice can for

instance opt for one of three increasingly onerous Ice Classes. Similarly, some tank er

own ers have voluntarily adop ted ES (enhanced scantling) descriptive notations, indicating

that m aterial scantlings are in excess of rule requiremen ts. It is un clear to what extent FPSO

operator s elect to imp ose standar ds high er than th e basic level.

It’s also worth no ting that th e principal comp laint about classification requ iremen ts is that

they are too onerou s on operat ing FPSOs, not too lenient.

3.1.5.1 Trends in Classification

Ship Classification is circum scribed by ad ditional requ irements, par ticularly those of the

International Maritim e Organisation, IMO and of the Interna tional Association of

Classification Societies (IACS). Both or ganisations rep resent v ery broad interests, includ ing

owners, operators, managers, and u nderw riters.





It is worth n oting ther efore that IACS and IMO requ irement s in respect of hull strength

have grown more onerous over the p ast few years, e.g.

1. While some FPSO operat ors pu rsue relatively bold inspection strategies with ever-

lengthening interv als, ow ners of classed tankers are now requir ed to carry out adetailed assessmen t of the longitudin al strength of their vessels after ten years.

2. Bulk carriers are now requ ired to consider fore-end impr ovemen ts to protect from

green wat er. Like FPSOs, and unlike most tank ers, bulk carriers have deck-mou nted

equipment th at is subject to d amage by green w ater.

3. Data is available1 to indicate that NE Atlantic maximum wave heights have increased

by as much as 1.5 m over the past 20 years. Protection & Indem nity2 clubs report

increased occurr ence of weather dam age to vessels. FPSO operators ad opt novel and

somewhat u ntried bow and hull designs, and suffer damage. There is a growing gap

developing between shipping practice and that of FPSO operators.

Classification rules are continu ally being rev ised and developed in the face of increasedtechnical challenges and y et there is a comm on comp laint that th ey are too inflexible for

operator s. There is some discussion that th at Class is an inad equate stand ard for FPSOs, yet

the won der is that op erators find it is so difficult to achieve the stand ard s required by class,

never mind exceeding them . Class rules certainly require to be upgrad ed but no matter

wh ich classification society is involved , they do app ear to provid e an oppor tun ity for

consistency and for p ooling experience.

3.1.6 Risk-based Maintenance

The imp ression w as gathered du ring the study th at risk based m aintenance was seen as an

opportu nity to redu ce the amoun t of maintenance needed and w ith minimal effort. This is

an inherently unsafe assumption.

3.1.6.1 Elements of a Risk-based Strategy

In order to have a pr oper risk-based system; certain elements are requ ired, includ ing:

xA system mod el, line list, asset invent ory, design/ construction dat a, etc.

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

xA mean s of ranking th e highest risk items,

xA Maintenance Scheme focused on t he highest risks AND the related failure mod es,

xA compreh ensive method for Event Iden tification.

Many risk-based strategies take a very optimistic app roach to the amou nt of effort required

to carry out the above requiremen ts. It is therefore common to find that the und erlying

assessments pr ovide insu fficient d etail as to the types of defects and the m eans of detectingand mitigating failures.

3.1.6.2 If not Risk-based, what?

Practice is divid ed betw een Risk-based and Rule-based. A difficulty of the former is that the

outp ut is sensitive to the risk assessment values and th ese 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





prob lem with th e latter app roach is that Rule-based str ategies are, by definition, inflexible.

An interm ediate strategy m ay offer an effective way forwar d.

x Initial examination and respon se to developm ents can be largely driven by generic

recommen dat ions, pooling experience and learn ing from a large fleet and bringing inrelevant p ractice from outsid e areas, e.g. tankers, foreign FPSOs, etc.

x Subsequent tactics shou ld be driven m ore directly by vessel–specific experience.

x Modelling and analysis should be aimed at identifying a rational, though n ot

necessarily a risk basis for examination and maint enance. The form er is achievable, the

latter not always so.

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

3.2.1 Pipework

Based on the d ata gath ered, over 80% of operators u se a nom inal 5-year risk-based

inspection cycle and ut ilise both non-destr uctive and visu al examinat ion over this period.

The remaind er use risk-based techniques to extend insp ection interva ls, in some cases to

seven years.

3.2.2 Tanks

Over 80% of operators use a 5 year cycle to program their insp ection and maint enance

rout ines, using close visual insp ections - generally involving rop e access - backed u p w ith

ultrason ic thickness m easurem ent and surface crack d etection in sp ecific areas. Tank coating

and an odes are examin ed generally for percentage deterioration. How ever over 16% of

vessels are on a 7-year risk-based cycle. From this, it could be inferred that som e of the

tanks would not be inspected u ntil the end of this period. While this long interval might be

justified as par t of an overall str at egy, it offers no assu rance as to th e effect on individ ual

tanks of any d eterioration attribut able to constru ction defects or to unforeseen p rocess

effects. It’s wort h bearing in m ind th at process conditions on some FPSOs are quite

dyn amic, wh ile the corrosion models often lag far behind . There is therefore the dan ger that

neither inspection nor m aintenan ce will intercept a deterioration pr ocess in good time.

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

The type of inspection adop ted by m ost respond ents is Close Visual Insp ection (CVI) and

not Genera l Visual Examination (GVE). This assertion is at variance with th e experience of

the auth ors. CVI is defined as a visual examin ation carried out within arm s reach or the

distance at w hich a person wou ld read a newsp aper or book, illum inated as necessary by

torch or other light sour ce. GVE is defined as a visual examination of a space as a whole

and at a distance. While GVE will perm it overall estimation of coating failure and buckling

of large mem bers, it cannot be exp ected to reveal crack like defects.

There appear to be a number of interpretations of CVI in use among respondents, many of

them vagu e. This distinction is imp ortant since both techniques have their advant ages.

Consider coatings and their imp ortance, especially in water ballast spaces. Traditionally,

vessel scantlings includ ed a mar gin that allowed for u ncertainties and pr ovided an effective

corrosion allowan ce at the design stage. This is seldom th e case now. Vessel designs are

now highly optimised and generally use the minimu m scantlings that the various class

societies state in their rules. Und er these circumstan ces, the coatings are now vital to the





integrity of the steelwork. GVE will often provid e adequ ate assurance of the overall

condition of coatings. By comp arison, tearing of brackets and necking of stiffeners can be

highly localised and w ill not be so appar ent. If these defects are to be located and assessed,

CVI will be requ ired.

3.2.3 Pumps

The current practice on pumps is split evenly between a 5-year planned maintenance and

inspection cycle and continu ous condition mo nitoring (CM), using vibration-m easuring

equipment.

CM usually comprises visual examinations with performance monitoring and vibration

mon itoring of one type or another. While benchmar king for vibration monitoring may be

mor e difficult on converted tankers, service experience indicates that a satisfactory d egree of

adv ance warning of failure can be achieved. There were no reported sud den failures of

systems m onitored in this way.

The other general practice entails routine mainten ance, dealing w ith time-based

deterioration of the equipment.

3.2.4 Control Systems

Again a 50/ 50 split between a 5-year cycle and continu ous monitor ing. Ongoing system

and component test routines app ear to be the norm and there was little to distinguish

between the chosen methods other than the degree of diligence 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 maint enance and similar

use of non-destructive examinations as for ballast systems. There were no repor ted cases of serious failures. General practice involves routine monitoring, intended to ensu re early

detection of deterioration. 50% of operators use rad iograph y to supp lement visual and

ultrason ic examin ations of this pipew ork, reflecting the higher level of risk perceived for

these systems.

3.3.2 Tanks

Over 65% of operators use a 5 year cycle with th e remaind er divided between 3, 7 and 10

years. Insp ection meth ods ar e broadly similar to ballast tank inspections with u ltrasonic

gauging of plates and examination of coatings and anode wastage.

Initial examination p eriods of up to 10 years are viewed w ith some degree of appr ehension

by the auth ors and for tw o reasons. First, if tanks are not inspected fully within th e first 3 to

5 years of service, no base line can be established. Second, a strategy th at d elays inspection

of a particular tank for ten years im plies a degree of accuracy in the p rediction of the

behaviou r of the stru cture, coatings, anodes, and att achment s not otherw ise justified by

experience.

The strategy for examining cargo tanks w as quite similar to that adop ted for ballast tanks.

This appear s strange because, while both hav e similar criticality in terms of hull girder

strength , they often have very different susceptibilities to corrosion and they d iffer

dr amatically in respect of the ease, expense, and imp lications of internal examinations.





Ballast tanks can generally be accessed w ith min imal disru ption w hile entry into cargo

tanks entails major disrup tion to, even suspension of, prod uction operations. One might

expect different app roaches, recognising different threats.

3.3.2.1 Slop Tanks

Slop tanks tend to suffer accelerated d eterioration and therefore wou ld be expected to

receive a greater level of inspections than cargo tan ks. This deterioration is largely

attributable to the relatively high op erating temperatures, the p resence of hot produ ced

wat er and low oxygen levels, resulting in instances of anaerobic sulphid e redu cing bacteria

(SRB). There were several known , and some susp ected, instances of damage includ ing

blistering and breakdow n of coating and rapid w astage of steel. These problem s were

exacerbated in the case of FPSO conversions w here, in som e cases, the slop tanks r eceived

insufficient attention during the conversion to prepare them for a duty cycle more onerous

than th at experienced by the same tanks in conventional tanker service.

Coating systems vary from simple coal tar epoxy to high-grade two p art systems. It was not

certain from the stud y w hether the pr edominant factor in d etermining the su ccess of the

coating system was the choice of coating or the stand ard o f application. Anecdotal evidenceindicates that norm al shipyard stand ards of preparation and application will not ensure

adequ ate lifetime perform ance in such a prod uction-critical and structur ally critical area.

Slop tanks are generally difficult to isolate and t o enter. This has driven some oper ators to

emp loy external means of examination, utilising thickness measurem ent at accessible

boun dar ies in order to interp ret the condition of the inaccessible boun d aries, i.e.

measurement through th e forward cargo tank bulkhead and through the after pum p room

bulkhead, particularly at t he bottom.

There was a certain resignation at th e instances of failur e in slop tanks. The failure

mechanism is well understood and the cure reasonably simple, however maintenance teams

are ham pered by poor initial design, first in failing to ameliorate the operating conditions

and second in pr oviding inad equate facilities for isolation and rep air of the tank. The knock on effect on prod uction of entering slop tanks for either surv ey or repair is noted a s a major

prob lem for maintenance staff.

Cargo Oil tanks are u sually par tially coated w ith a full coating specified for the bottom 3m

and top 3m.

3.3.3 Pump & Control Systems

The system emp loyed is similar to that used on the ballast system.

3.4 Hull

External inspections of the hull, wind and water areas, sea chests and the turret vary among

the operator s. 30% operate a 2½-year cycle, wh ich equa tes to the man dator y InternationalMaritime Org anisations (IMO) requirem ent for In-Water Surv ey twice in 5 years. 30%

inspect on an annu al basis. The remaind er were a little unclear as to what th ey actua lly do.

All operators u se similar inspection techniques, external examinations via an ROV, coating

and anod e inspections, close visual exam ination. The primar y difference is in the frequency

at wh ich these activities take place. All operators inspect turrets at least annu ally, with th e

extent of examination largely govern ed by m atters of ROV access. Impr essed Cur rent

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

failur e records: both systems being practically redu nd ant on all but on e of the vessels

considered. With maintenance and inspection bud gets und er constant pressure, it is

disappointing to have to commit resources to managing systems with little or no

operational function.

Hyd rau lic locking of steering gear is never ad visable. While the relief valves will permit the

rud der to give un der w ave loading, there is then no means of recovering position. The next

wav e can then force the tiller against its stops and can cause severe da mage, even

amou nting to total failure of the steering gear. After the Amoco Cadiz disaster in the 1970s,

mechanical stops were required in ord er to restrain the rud der in t he event of hydraulic

failur e. Given the physical size of steering gears and the conditions und er which these stops

might be called u pon, these mechanical stops have prov ided far m ore psychological than

ph ysical security. It is difficult to conceive of a situation wh ere it wou ld be feasible to install

these d evices in the event of failure.

Much is mad e of the contention th at rud ders experience greater forces in FPSO service than

in tanker service. This ignores the fact that the rud der failures encountered h ave been as a

result of single episod es, rath er than cum ulative effects. Such instances of steering gear

overload are an unnerving, but not entirely unusual, occurrence on ships; however they

rarely result in d amag e to the steering gear since the system s designed to yield to the forces

and then to recover.

The situation regard ing thru sters appears equivocal. Some vessels have no provision, some

have provision, but h ave not fitted them , and some vessels have them fitted but are u nable

to maintain position by using thrusters alone. Two instances w ere discussed in the course

of the study: one where a sw ivel bearing failed and one w here it was required to examine

the spid er at close range. In both cases, a tu g was chartered t o maintain th e vessel on

station. Over the ran ge of vessels considered, it is questionable wh ether the comp lication or

expense of installing or ma intaining th ruster s is justified.

3.5 Caissons

Not a ll vessels have caissons: of those that h ave, two u se a 5-year insp ection cycle and one 4

years. Insp ections are close visual, supp lemented by ultrasonic and ROV insp ections. One

operator has a program me to m onitor coatings and anodes.

The only reported failure w as du e to a high p otential difference between a p um p bod y and

the caisson material. This shou ld have been anticipated at the design 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 and33% using a 2 ½ to 3-year cycle. Visual examin ations and coating inspections are th e norm al

inspection method s. All operators check the up per d eck thickness with u ltrasonic, but th e

frequency varies as above.

Where cracking has been found , it has generally been attributed to inadequ ate design or

installation. Although repa irs are normally relatively minor in scale, they can be difficult to

achieve with the u nit in prod uction.





3.7 Tank Venting System, Pipework, PV Valves and Seals

Inspection cycles are evenly split between 5 & 3 years. Close visual insp ections an d

ultrasonic would appear to be the primary inspection methods. UT is used to check pipe

thickness in man y, but by no means all cases. One operato r has a test progr amm e for

pressure testing pipework and valves.

Maintenance of seals and Pressure/ Vacuu m (P/ V) Valves appears to be well addressed in

all cases. Op erational lessons app ear to have been learned from an incident of tank

buckling some years ago.

3.8 Cranes

Cranes rep resent a significant safety risk and are complex, involving significant m echanical,

structu ral, and control and safety aspects. The mainten ance and insp ection arrangem ents

wer e however found to be the most compr ehensive and consistent. The use of a small

nu mber of specialist prov iders ap pears to be a critical factor. Systems, records, incident

report s, lessons learned, etc., all appear to be man aged comp etently.

The mainten ance criteria include comp liance with the requ irements of LOLER, SI

1998/ 2307, and variou s classification requiremen ts. All operators carry out rocking tests

and grease analysis of slew rings as a ma tter of routine.

3.9 Thrusters

Three operator s use a 5-year cycle; one uses a 2-½ year cycle and th e remainder an ann ual

cycle. In some cases, fun ction tests are carried ou t weekly and oil analysis completed w here

facilities perm it.

Vibration monitoring equ ipm ent is installed in some instances and ROV inspections carried

out on others. Their location and relative inaccessibility norm ally preclud es intru sive work.

Most operators have plans in place to deal with sud den breakdown or failure, using tugs

where n ecessary. Two operators reported instances of thruster motor failure d ue to thrustbearing failure. Being inactive for long p eriods, these motor s are subject to brinelling

effects. In one case the coverage of vibration monitor ing wa s increased to includ e these

motors after the event.

3.10 Swivels and Drag-Chains

The inspection of swivels and dr ag chains falls into two m ain categories. Three operator s

opt for annu al visual examinations, with ROVs for und erwa ter sections. Two have a 3-year

cycle and one op erator h as a 5-year cycle.

At least one operator h as had t o renew a set of swivel seals due to ingr ess of salt and gr it

par ticles. The exercise involved fitting a more robu st system, implying that th e original

design may not h ave been equal to the service requirement.





4 Recommended Practice

4.1 Ballast Systems

4.1.1 Pipework

If comp leted to a compr ehensive maint enance plan, the 5-year cycle wou ld 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

structu re and th e predictive response of the structure, then to tailor the inspection strategy

to these threats. The extent of the analysis should b e sufficient to iden tify and ran k critical

highly stressed areas of the stru cture as w ell as fatigue sensitive locations. The followingare recomm ended:

a. Carry ou t a full GVE of all tanks within the first 5 years to prov ide a baseline for the

vessel in terms of design and build qu ality

b. Ensure comp lete coating of ballast tank intern als: pr eferably light coloured or w hite.

This will provide a high contrast background and allow rapid detection of coating

breakd own , incipient cracking, and blistering.

c. Ensure tha t edd y curren t detection is available as a first-line assessment t ool. If there is

no eddy current indication, there is seldom need for further investigation.

d . Ensure tanks are comp letely stripp ed prior to entry. This w ill speed examina tion of tank bottoms, particularly in w ay of bell mouths and mouse h oles.

e. Provide good lighting, either installed or portable. This is seldom a considera tion on

tankers since the time element w hen carrying ou t surv eys is not so critical, whereas th e

defermen t cost of FPSO tank entry is particularly high. Bear in mind t hat air-driven

lanterns can be difficult to manoeuv re with ease and more inventive lighting solutions

should be considered.

With the above m easures, it will generally be possible to carry ou t a compreh ensive

examination and to have a high d egree of confidence in the results, in terms of buckling,

tearing, cracking, coating damage and anode wastage.

Thereafter examin ation intervals can be adjusted to tak e accou nt of the tank conditions.

4.1.3 Ballast Pumps

On the basis of the results of this stud y, either m ethod could be viewed as good p ractice,

best practice being very mu ch a matter of choice for individ ual operator s. 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 insp ection routines rigorously and r ectify defects at the comp onent

level, before they escalate to system d eterioration.

4.2 Cargo Systems

4.2.1 Pipework

If comp leted to a compr ehensive maint enance plan, the 5-year cycle wou ld be an acceptable

strategy toward ensuring early d etection of wastage and providing assurance that the

systems rem ain effective. In add ition an annu al external examination of the deck lines

should be carried out to detect breakdown of coating systems.

4.2.2 Cargo Tanks

Best practice would be first of all to und erstand the criticality of cargo tan ks, both in term s

of the associated safety risks and of the all-up cost of intervention, i.e. isolation, defermen t

manp ower, preparation and reinstatement. The inspection and m aintenance strategy

should acknowledge these risks and costs.

The following are recommended:

a. The inspection strategy should be founded on und erstanding the threats to the integrity

of the tank structur e and on predicting the response of the structur e. The inspection

plan shou ld then be tailored to these threats. The extent of the analysis should be

sufficient to ident ify and ra nk critical areas of stress in the structu re as well as fatigue

sensitive locations.

b. Provide a flexible and comp rehensive mean s of isolating, inerting, and ventilating

individ ual tanks. Traditional tanker p ractice will generally be insufficient for this

pu rpose since FPSOs suffer from different time and resour ce constraints in examining

tanks. It should be possible, at the least, to isolate two ad jacent tanks withou t having toshut down production.

f. Carry ou t a full assessment of all tanks w ithin the first 5 years to pr ovide a baseline for

the vessel in terms of design and build qu ality. This shou ld include visual examination

to an app ropr iate extent to establish actual conditions at each frame interval along the

cargo area. There may be a case for inferring the condition of a port tank from th e

starboard and vice versa.

g. Where possible, use high contrast coating on tank bottom and r oof. This will allow

rapid detection of coating breakd own , incipient cracking and blistering.

h. Ensure tha t edd y curren t detection is available as a first-line assessment t ool.

i. Ensure tanks are comp letely stripp ed prior to entry. This w ill speed examina tion of

tank bottoms, particularly in w ay of bellmouth s and mouse holes.

j. Ensure that tan ks are clean prior to entry. This can best be achieved by retaining,

mainta ining and operating tank-cleaning systems. This pra ctice has the add itional

adv antage of preven ting the bu ild-up of slud ge, with the associated risk of SRB attack.

k. Provide good portable lighting. Tank entry dur ation can be shorten ed consider ably by

this simp le measure.





With the above m easures, it will generally be possible to carry ou t a compreh ensive

examination and to have a high d egree of confidence in the results, in terms of buckling,

tearing, cracking, coating damage and anode wastage.

Thereafter examin ation intervals can be adjusted to tak e accou nt of the tank conditions.

4.2.3 Pumps, Controls

Recomm ended practice is similar to that emp loyed on Ballast systems.

4.3 Hull

Best pr actice is considered a 2½-year ROV insp ection, measurin g hull potential. Op erators

should h ave a m eans of cleaning sea chests grids and should retain blanking arrangements

for sea valve main tenance. Consideration shou ld be given to removing items durin g

conversion wh ich are un likely to be used – rud ders, prop ellers 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 will be to keep steering motor s runnin g. The

design of the steering gear allows for the effect of wave slam and will permit th e rud der to

both give und er wave loading and to recover after imp act.

4.4 Caissons

A pr ogram of thickness determ ination, using variations on riser inspection tools, can

prov ide early detection of wastage. Wastage rates can how ever be except ionally high and

the cost of intervention m eans that a materials review w ould be recomm ended, taking

app ropr iate action in respect of material change out insu lation, shielding or other

preventive measures.

4.5 Deck Structures, Pallets, walkways, and upper deck plating GVE is usually adequ ate, with su pp lementary U ltrasonic Testing (UT) of main d eck plating.

4.6 Tank Venting System, Pipework, PV Valves and Seals

Conventional techniques for examin ing and mainta ining these systems app ear adequ ate. It

is importan t how ever to continue to stress the criticality of these systems in relation to hu ll

strength , fire and explosion.

4.7 Cranes

Total Vendor Maintenan ce progr ams are recomm ended . Service experience here und erlines

the benefits of emp loying experts with th e associated critical mass in investm ent in

technology and training.

4.8 Swivels, Drag-Chains

While swivel seal and bearing failures have been encoun tered, th ere was little informa tion

available from wh ich to draw generic lessons. As both systems may be considered to be

based on p roprietary designs, manufacturer advice would appear to constitute best pr actice

at present.





Given the sever e consequences of seal failure, it is recomm end ed th at th e criticality of seal

monitoring and protection systems — header tan ks, pressurisation system s, 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 ra nge of generic techniqu es

app lied to IRM on FPSOs. The conclusion is that, while there are

some ou tlying cases, opera tors are relatively consistent in their

pra ctices. The table also indicates that general practice remain s

relatively conservative d espite the app arent nov elty of some risk-

based strategies. This wou ld app ear to leave ample scope for

development and improvement.

A v e r a g e I n s p e c t i o n I n t e r v a l ( m o n t h s

G e n e r a l E x a m i n a t i o n

G e n e r a l V i s u a l

C l o s e V i s u a l

U l t r a s o n i c E x a m i n a t i o n

R a d i o g r a p h y

M P I

R O V E x a m i n a t i o n

C o a t i n g E x a m i n a t i o n

A n o d e I n s p e c t i o n

V i b r M o n i t o r i n g

S y s t e m T e s t

R o c k i n g T e s t

G r e a s e A n a l y s i 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 12 0 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 12 0 17 %

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

Slops Tanks 120 17 %

Pumps 25 83% 83%

Control Systems 27 100% 100%

Ta nk s & Ab ov e Wat er Con ti nu ous Sur ve y Hul l 72

Subsea 30

External Sea Chests 33 83% 83% 100% 100% 100%

Internal Sea Chests 45

Turret 27 100% 83% 1 00% 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% 1 7% 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% 3 3% 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

App end ix A contains a list of IRM pr oviders. The list is not extensive but it serves to

illustra te a rang e of service organisations w ith d irect experience of in-service repair to

FPSOs.





Appendix A – List of Repairers



List of Repair Organisations

StudyintoBestPractice

lasWinch&oistServicesKnockl eeBiggarLanarkshire+44(0)1899221577 +44(0)1899221515 BalmoralBalmoral ParkLoirstonAberdeenAB123Y+44(0)1224859059 +44(0)1224859059 G.JWortelrjBV POBox5003NL-3008Rotterda+3110429222+311042964 LloydsBel AnchorHousDumballsRCardiffCF105TX+44(0)2920231296 +44(0)2920342719 VlaardingenAnchor&i POBox473130AAVlaardingenTheNetherls+31(0)10434CranesOffshore CranEngineeringtBurnsideDriveFarburn IndustEstate,DyceAberdeenAB210HW

+44 (0)1224797300 +44(0)1224797301SparrowsOffshoreServices Ltd

DenmoreRoadBridge ofDonAberdeenAB238JW+44 (0)1224704868

Pipework & GeneralEngineering3 PlusEngineeringtBadentoyRoa,BadentoyParkPortlethenAberdeenAB124YA+44 (0)1224782211 +44(0)1224782266

ABB OffshoreSystems LtdHareness RoaAltensAberdeenAB123LE+44 (0)1224872211 +44(0)1224894840

Aberdeen Val& FittingCotUnit1,StoneywParkStoneywoodRoAberdeenAB217DZ+44 (0)1224722468 +44(0)1224723009

Agra (PrecisioEngineering)Ltd 15Ure StreetDundeeDD1 5JD +44 (0)1382229333 +44(0)1382226918AirPower&Hydraulics Lt15WattRoadHillingtonEstate+44 (0)141 8104511 +44(0)141 382




Glasgow G52 4PQ

AJT EngineeringLtd

Craigshaw Crescent West TullosIndustrial Estate Aberdeen AB12 3TB

+44 (0) 1224871791

+44 (0) 1224890251

Alfa Laval Ltd.,Oilfield Division

6 Wellheads Road Farburn IndustrialEstate Aberdeen AB21 7HG

+44 (0) 1224424300

+44 (0) 1224725213

CaledonianPetroleumServices Ltd

Unit 4 Howe MossAvenue

Kirkhill IndustrialEstate

Dyce

Aberdeen

AB21 0GP

+44 (0) 1224725345

+44 (0) 1224725406

Grayloc Hydropark Tern Place,

Denmore Road Aberdeen AB23 8JX

+44 (0) 1224222790 +44 (0) 1224222780

Hydra Tight Ltd Howe MossCrescent Kirkhill IndustrialEstate Aberdeen AB21 0GN

+44 (0) 1224770739

+44 (0) 1224724175

Mach-TenOffshore Ltd

Pitmedden Road Dyce Aberdeen AB21 0DP

+44 (0) 1224773565

+44 (0) 1224773568

Micron EagleHydraulics Ltd

Blackburn IndustrialEstate Kinellar Aberdeen AB21 0RK

+44 (0) 1224790970

+44 (0) 1224790970

S&D FabricationsLtd

Greenbank Crescent East Tullos Aberdeen AB12 3BG

+44 (0) 1224895564

+44 (0) 1224899065

SchoolhillHydraulicEngineering CoLtd

3 Greenbank Place East Tullos Aberdeen AB12 3RJ

+44 (0) 1224871086

+44 (0) 1224897135

TransmarkValves Ltd

Anglian Lane Bury St Edmunds Suffolk IP32 6SR

+44 (0) 1284701206

+44 (0) 1284705596

WhittakerEngineering

Hindwells Stonehaven Kincardineshire AB39 3UT

+44 (0) 1569762018

+44 (0) 1569766701






LE11 1HJ

DeebridgeElectricalEngineers Ltd

Craigshaw Road West Tullos IndustrialEstate,Tullos

Aberdeen AB12 3AR

+44 (0) 1224 871548 +44 (0) 1224899910

Dowding & Mills(Scotland) Ltd

Lochlands IndustrialEstate Larbert Central FK5 3NS

+44 (0) 1324 556511 +44 (0) 1324552830

KongsbergSimrad

Campus 1

Science & TechnologyPark Bridge of Don Aberdeen AB22 8GT

+44 (0) 1224 226500 +44 (0) 1224226501

StephensonMarine

Wrecclesham Farnham Surrey GU10 4JS

+44 (0) 1252 714199 +44 (0) 1252733662

Inspection/Repair General

CAN Offshore Hareness Road

Altens

Aberdeen

AB12 3LE

+44 (0) 1224 870100 +44 (0) 12224870101

Also offer riser

inspection tool

for caissons, as

well as risers

CORE TechnicalServices

Howe Moss Drive Kirkhill IndustrialEstate Dyce

Aberdeen AB21 0GL

+44 (0) 1224 771118 +44 (0) 1224771112

E M & I Marine

Ltd

Wrecclesham

Farburn Terrace Dyce Aberdeen

+44 (0) 1224 771077 +44 (0) 1224771049

Hi-Rope Unit 8 WoodlandsDrive Kirkhill IndustrialEstate Dyce Aberdeen

AB21 0GW

+44 (0) 1224 772161 +44 (0) 1224772156

TRACInternational Ltd

Unit 2 Howe MossDrive Kirkhill IndustrialEstate Dyce

Aberdeen

+44 (0) 1224 725800 +44 (0) 1224725801



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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Main tenance Sys temWho 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

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

during warranty periodDo you still use vendors to service the system

If not, why not

Do you use campaign maintenance squadsWhere

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

Why

Have you changed your vendor/campaign strategyWhy

Do you have a Risk-Based Inspection (RBI) Philosophy

If so, what is it based onWho manages inspection

In respect of the systems below, do thefollowing factors influence Reliability,Availability, Maintainability andOperability

a

Weather

b

VesselMotion

c

Vibration

d

Access

e

Design

f

MaterialSelection /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.



Failure s / Repairs 1I n respec t o f sys tem fa i lu res in the areas of int 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 likeWas 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 FPSOsWas the failure

Generic to Oil & Gas installations

Verification and ClassificationIn the course of the repair/reinstatement, were you aware of anyconflict between ……

Verification & North Sea Practice

Was the repair successful

Who carried out the repair

Has the failure driven a change to your Inspection or Maintenancepractice

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

Vendor/OEM

Main contractor

Specialist Contractor

Were repairs/reinstatement carried out by

Local Vendor/Non-SpecialistContractor

What recommendations did you feed back into design to eliminatethese failures

Have you an established “Lessons Learned/ Good Engineering

Practice” system to capture this informationIs this information available Internally

Is this information available Externally

OP033FPSO Repaire and Maintenance

Documents