Corrosion & Integrity Mgmt

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SPE-ATW Corrosion and Integrity Management: Are we Doing the Best we Can?

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SPE Workshop Report

SANA Lisboa Park Hotel, Lisbon, Portugal

18-21 June 2007

Corrosion and Integrity

Management: Are we doing the bestwe can?

Author - Peter SmithDate 09/07/2007


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Contents

Introduction ....................................................................................................... 5

Day One Tuesday 19thJune 2007................................................................. 6

Opening Address: 8.30-9.30............................................................................. 6

Presentation - Corrosion and Integrity Management: are we doing the bestwe can? ......................................................................................................... 6

We have come along way since the early explorations in the offshoreindustry. ..................................................................................................... 6

How far have we come in corrosion mitigation technology?..................... 7

The overall corrosion community is performing very well ......................... 8

Where are we going wrong? ..................................................................... 9Health and Safety Regulations.................................................................. 9

The Reality................................................................................................. 9Media Criticism.......................................................................................... 9What do we need to improve?................................................................... 9

Session 1: 9.30-12.30 Materials Selection & Integrity ManagementConsiderations in Design................................................................................ 10

Session 1 - Introduction (MS)...................................................................... 10

Presentation - Pipeline Corrosion and Integrity Management .................... 10Discussion Period Use of Software in Corrosion Management ....... 11

Presentation Continued ....................................................................... 13

Discussion Period Corrosion Inhibitor Issues................................... 13


Discussion Period Weld Corrosion Issues........................................ 14


Discussion Period Monitoring Methods ............................................ 15Presentation Continued ....................................................................... 16

Discussion Period Corrosion Damage Measurement ...................... 16

Presentation Meeting the Design Intent................................................... 18

Discussion Period Meeting the Design Intent................................... 18


Discussion Period Coatings and Insulation Issues........................... 19


Discussion Period Use of Corrosion Resistant Alloys ...................... 20


Discussion Period Design Standards ............................................... 21

Presentation Materials Selection and Integrity Management in the Design

Stage ........................................................................................................... 22Discussion Period Inspection Issues ................................................ 22


Session 2: 13.30-15.30 Causes of Corrosion.............................................. 24

Presentation Causes of Corrosion ........................................................... 24

Discussion period CO2and Organic Acid Corrosion Mechanisms... 25Presentation continued ........................................................................ 26

Discussion Period H2S Corrosion Mechanism ................................. 27


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Presentation Causes of Corrosion in Corrosion Resistant Alloys............ 28

Discussion Period CRAs.................................................................. 28Presentation Corrosion under Insulation (CUI)........................................ 30

Discussion Period - CUI....................................................................... 30

Presentation Prediction Success ............................................................. 31

Discussion Period Corrosion Prediction ........................................... 31

Session 3: 16.00-18.00 Design of Corrosion Mitigation Strategies............. 33

Presentation Design of Corrosion Mitigation Strategies .......................... 33

Presentation Strategy Identification and Implementation ........................ 34

Pro-activity in identification:- ................................................................ 35

Presentation Design of corrosion Mitigation Strategies........................... 35

Discussion Period Corrosion Mitigation Strategies .......................... 35

Presentation continued ........................................................................ 36

Discussion Period Integrity Management ......................................... 37

Day Two Wednesday 21stJune 2007.......................................................... 40Session 4: 08.30-12.30 Implementation of Corrosion Mitigation Strategies.

........................................................................................................................ 40

Presentation Corrosion Mitigation Chemical Selection and Treatment ... 40

Discussion Period How Do We Select the Correct Inhibitor?........... 40


Discussion Period - How much inhibitor should we use?.................... 42

Presentation continued ........................................................................ 44Discussion Period - How should inhibitor be applied? ........................ 45


Discussion Period - How do we know it is working? ........................... 45

Presentation Implementing SRB MIC Mitigation and MonitoringEffectiveness............................................................................................... 46

Discussion Period - Implementing SRB MIC Mitigation and MonitoringEffectiveness........................................................................................ 47

Presentation continued ........................................................................ 48Discussion Period - Implementing SRB MIC Mitigation and MonitoringEffectiveness........................................................................................ 51

Session 5: 13.30-15.30 Performance Measurement................................... 53

Presentation Corrosion Performance Measurement ............................... 53

Discussion Period - Corrosion Performance Measurement ................ 53


Discussion Period - Corrosion Performance Measurement ................ 55


Discussion Period - Achieving target values ....................................... 56


Discussion Period Traffic lights and KPIs Overall ........................... 57


Discussion Period Performance Comparison................................... 58


Discussion Period Consequences of KPI Failure............................. 58


Presentation Legislative View on Corrosion Performance Measurement59


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Discussion Period Legislative View on Corrosion PerformanceMeasurement ....................................................................................... 59

Session 6: 16.00-17.30 Completing the Cycle ............................................ 60

Discussion Period Competency and Recruitment ............................ 61

Discussion Period Intelligent Pigging ............................................... 63

Discussion Period Inhibitors ............................................................. 64

Day Three Thursday 22ndJune 2007 .......................................................... 66

Session 7: 09.00-13.00 The Way Forward.................................................. 66

Workshop questions feedback............................................................. 66

Presentation The Use of Probabilistic Modelling ..................................... 66

Discussion Period Use of Tools for Corrosion Assessment............. 66


Discussion Period Intelligent Pigging ............................................... 67

Discussion Period Techniques for Corrosion Assessment............... 68

Knowledge Transfer Joint industry projects: Operators View.................. 70

Discussion Period Knowledge Transfer............................................ 71


Knowledge Transfer Joint industry projects: Research Institutes View... 72

Discussion Period Knowledge Transfer and JIPs............................ 73

Regulatory Framework Guidance for Corrosion and Integrity Management..................................................................................................................... 74

Discussion Period Guidance for Corrosion and Integrity Management............................................................................................................. 76

Regulatory Framework Corrosion, Pipeline Integrity and US FederationRegulation and Legislation.......................................................................... 76

Discussion Period - Corrosion, Pipeline Integrity and US FederationRegulation and Legislation .................................................................. 78

Poster Presentations ...................................................................................... 80

Workshop Summary Are we Doing the Best we Can?................................ 81


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Introduction

The notion of this report is to provide an overview of the presentations anddiscussion sessions at workshop. The material in this report presents thegeneral information presented by speakers in each session and provides a

reference to the main discussion topics throughout the workshop. Referencesto the speakers during discussion periods have been provided wherepossible. But it is important to note that questions and answers in this reportare not direct quotes.

This report follows a chronological structure synonymous with that of thetechnical agenda issued at the workshop. A rearrangement in the schedule atthe workshop sees the presentation by Kirsten Oliver situated in Session 7 ofthis report instead of session 5. The presentation from Andrew Duncan inSession 7 has also been omitted. This was available as a handout at theworkshop. There was no discussion period associated with this presentation.


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Day One Tuesday 19thJune 2007

Opening Address: 8.30-9.30

George Winning (GW) Chairman SPE ATW Lisbon, Integrity TeamManager, Clariant Oil Services.

The opening address introduced the purpose of the workshop, the generaldiscussion areas to be addressed in each session and the workshopcommittee.

A workshop question was introduced with the aim to find a distinction inpeoples understanding.

Can you tell us what you understand by the following terms?

Integrity management

Corrosion management

Presentation - Corrosion and Integrity Management: are wedoing the best we can?

Andrew Duncan (AD) Specialist Inspector, Corrosion and Materials OffshoreDivision HSE.

In the current climate corrosion is international news. It is currently verydifficult to be an oil and gas operator.

Oil and gas providers are being pulled from one side by Politicians and on theother side from Green Peace and other environmental groups.

All oil and gas companies want to do the best they can. They all want to workwith competent suppliers and contractors.

We have come along way since the early explorations in the

offshore industry.

The Forties Alpha Field 1971 initially constructed from carbon steel hasprovided many learning opportunities. After 29 years of learning theShearwater field in 2000 was constructed mainly of Duplex SS. During thisperiod the understanding of alloys in the industry has increased considerablybut this however has generated new challenges corrosion of exotic alloys,stress corrosion cracking and some of the old problems e.g. internal corrosionis still not yet fully understood.


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The Pipa Alpha disaster in 1988 was the cause of 167 deaths. While thisdisaster was not corrosion related, it demonstrates the possible effects ofbreakdowns in our integrity management systems.

Statistics from the HSE show that in general in the UK there is an increasing

trend in leak frequency. Although in recent periods of 2005-2006 there hasactually been a decrease recorded.

The ratio of internal to external leaks currently residing at 5:1 is on theincrease and leak frequency statistics collected in accordance with RIDDORshow that 13% of all leaks are due to corrosion. A breakdown of theunderlying causes reveals that 32% of inspected occurrences were due toinadequate inspection/condition monitoring, 30% were due to inadequatedesign and 23% were due inadequate procedures.

It is expected that the failure frequency over the lifetime of an installation willfollow the profile predicted by the Bathtub model, where a higher failure

frequency is expected at the early part of life followed by a long period of lowfailure frequency incorporating the main working lifetime with a further rise infailure frequency near the end of the life of an installation. Failure frequencystatistics from the North Sea sector for pipeline and installation failures showno correlation with this prediction.

Another example of integrity management systems failing was in the BombayHigh Disaster 2005. This disaster occurred during the transfer of an injuredperson from a support vessel to the Bombay High platform. The weatherconditions were reported as adverse with strong winds and during theoperation the support vessel collided with a riser causing a fire. Oninvestigation, the integrity management system allows transfers from supportvessels to the platform, but only in normal weather conditions.

Recently in the North Sea there have been no major disasters but there havebeen several accidents involving hydrocarbon escapes and fires resulting inthe deaths of eight people. Two men in a recent case were killed by a releaseof hydrocarbon as a result of a corrosion related failure of a pipeline andclamp near the flange of the line.

The use of high performance materials especially alloys has introduced morecomplex failure mechanisms such as stress corrosion cracking. Originatingboth internally and externally this mechanism is believed to be caused by

hydrogen embrittlement.

How far have we come in corrosion mitigation technology?

Since the early oil and gas exploits technology and awareness has increasedsignificantly. The de waard & Milliams nomogram provides a good basis forthe prediction of CO2corrosion and the development of advanced predictivealgorithms. The concept of field monitoring is now being implemented my


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many and the technology required for this is continually improving.Electrochemical analysis techniques developed and tested in laboratories arenow becoming much more robust and usable in the field. Ultrasonicmonitoring is available and the culture of laboratory testing is changing tobecome more field orientated by examining flow loops and developingtechnology for field testing.

The concept of corrosion risk assessments in the field is now practicedheavily in the oil and gas industry. Risk based inspection provides a means tobring corrosion engineers, inspection engineers and modern mathematicaltechniques together to provide written schemes of installation examinationbased on theoretical corrosion knowledge and quantitative risk analysis.

The overall corrosion community is performing very well

There is increased understanding in the corrosion mechanisms observed inthe field and why the techniques employed dont always work.

There is a major concern however across the industry relating to the ageprofile of employees. A recent observation highlighted that the average age ofpersonnel on platforms in the North Sea was 54!

The condition of rigs in the North Sea has been heavily affected by thefluctuating price of oil. An oil price of $10 per barrel (bbl) was the cause ofmany problems that have still not yet been overcome. New operatingphilosophies were adopted such as Cost Reduction in the New Era (CRINE)and wholesale redundancies of new and experienced engineers took place inan attempt to cut costs.

Currently the price of North Sea oil is steady at $60-$70 bbl. The rigs receiveattention but they are still not in a good condition, why?

There has been a reduction in the overall production in the sector. Combinedwith a history/culture of cost saving, managers are continually driving costsaving exercises. There is inadequate planning for the future and recruitmentdrives dont provide enough engineers to fill the voids created in the past. It isdifficult to encourage the youth to enter the oil and gas industry. There is needfor more day to day maintenance offshore by painters etc, there are howevernot enough beds available in many cases for this to happen.

The industry as a whole is suffering with a large tax burden with few taxincentives and there is considerable pressure from external bodies. The USChemicals Board has issued several concerns directed toward the safety andintegrity management of oil and gas installations. The Baker Report suggeststhat companies are not effective at leadership. The Health and SafetyExecutive have issued fourteen improvement notices to Floating Productionand Storage Facilitys (FPSO) recently requesting evidence of compliance.Four of which were issued on the same day!


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Where are we going wrong?

Is the information chain working properly?

Top management make safety statements, these are then filtered toengineers, and then to the operational workforce. Is the message actually

getting through?

Health and Safety Regulations

A brief introduction to the Health and Safety Regulations was made withparticular reference to regulations 3 to 9 and regulation 19. The requirementfor risk assessment was presented and the need for a competent workforce,the correct materials, their correct use, effective inspection and the correctinstallation of fire/explosion prevention its maintenance.

The Reality

There were several case studies presented showing photographs of corrosionrelated safety issues;

I-beams with severe corrosion damage including large holes,Helicopter deck supports with large holes present,Firewater pipe work full of holes causing a pipe rupture to occur during a droptest.Blocked fire deluge nozzles,Nuts and bolts almost unidentifiable on the flanges of a main gas line,

Grating collapsing causing an employee to loose his leg,Grating placed upon grating,String being used to hold chemical injection skids in place.

Media Criticism

There were several headlines presented demonstrating some of the recentmedia criticism directed to the oil and gas industry from the Times, PrivateEye, Upstream, and other media publications. Many of these articles weredirected towards the HSE who offered comments summarising their role inencouraging good industrial practice and prosecuting companies whereblatant disregard for the law has occurred. The HSE make it clear that theybelieve that discussion to encourage compliance is more effective thanprosecution and is their main objective.

What do we need to improve?

There was several improvement areas identified in this presentation and theyinclude;


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Fabric and maintenance,Development of Internal corrosion understanding and resistant materials,Apply the available technology more widely,Persuade managers that controlling corrosion is the key to controlling costsetc,

Have no more disasters.

Session 1: 9.30-12.30 Materials Selection & IntegrityManagement Considerations in Design.

Session Managers:-

Derek McNaughton (DM) - Corrosion Engineer, Oceaneering InternationalMike Swidzinski (MS) - ConocoPhilips

Session 1 - Introduction (MS)

There are some interesting points to note from Andrew Duncans openingpresentation.

It is evident in the North Sea sector that many structures manufactured fromcarbon steel are still in use 40yrs since installation. In some cases carbonsteel structures have outlasted structures manufactured from more recentlydeveloped technically advanced stainless alloys.

Asset Integrity and its management are paramount for the safe operation andlongevity of installations. Integrity management systems should include alloperations from cradle to grave of an installation. Integrity and corrosionmanagement should be understood and appreciated.

What does this mean for materials selection?

Presentation - Pipeline Corrosion and Integrity Management

Mike Joosten (MJ) Principle Metallurgical Engineer, ConocoPhilips

- Every pipeline is corroding.- The integrity management of a pipeline is controlling the rate of

corrosion so that the pipeline meets its design life and requirements.- Every material is susceptible to cracking.- Integrity is avoiding the use of materials that are incompatible with their

environmental conditions.

The objective of integrity management is to;


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Identify drivers of corrosion;

- Corrosion mechanisms,- Temperature, H2S, CO2, bacteria, chemistry of produced fluids,- Wall shear, production solids (sand) causing erosion corrosion,

- Feasibility of inhibitors for corrosion control.

Identify constraints;

- Location, workforce, local pipeline content and quality,- Chemical application, schedule, costs and monitoring by inspection

pigging.

Inhibit corrosion of pipelines;

- Material selection carbon steel?- Inhibitor application limits, selection and transport,

- Flow modelling Topographical, multiphase flow, turbulence.

Develop erosion design philosophies;

- Sizing topside operations using industrial models e.g. Tulsa model,- Considering erosion characteristics and flow patterns,- Assessing the formation of corrosion pits and their effect.

Make critical decisions;

- Selection of contractors need experience,- Pipeline diameter flow regime,- Inspectivity access, bends etc,- Fabrication welds and filler considerations,- Hydrotesting to monitor integrity of pipeline,- Dewatering and drying residual salts,- Corrosion monitoring locations easy, accessible ones,- Baseline inspection is this necessary?

Discussion Period Use of Software in Corrosion Management

Q During the design phase can you use the ionic power index to estimate

the corrosion effect of combining salts in fluid?

A (MJ) The ionic strength of a fluid is not really and issue in corrosion butthere is certain ionic strengths are required to support some corrosionpathways. Software can be used as a design aid.Q (MJ) The use of software and corrosion prediction software as a designaid in integrity management, any comments?

A Software provides very conservative answers.


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A Very little knowledge built into corrosion predictive software (Latestknowledge circa 1974).

Q (MJ) If software was made openly available would it help?

A Yes, if it is free and made into a standard.

A Depends on interpretation of the model data experience is necessary need workforce to be intelligent and knowledgeable.

A Models used in design and then throughout the life of an asset are flawedbecause they do not currently run with real data over the life of the asset.

Need to use models with real online data so that they incorporate the latestinformation e.g. oil wetting.

If a model is run initially on a design there will be no corrosion risk due to oil

wetting initially there is no oil wetting. There is still however a risk duringoperation and if the oil wetting data is not fed into the model the risk will notbe observed.

Corrosion risk based inspection regimes are useful but where is the riskcoming from are the models being used fed with up to date corrosion relateddata?

A Models provide uncertainty due to the data they use.

A It is tough to design a system for a field you initially know little about and itis even harder to convince a manager to use the exotic materials that may benecessary later in the life of the installation.

A How good is you capability to react to change? E.g. as the water cut rises.Do you design for the risks that might develop? It is very difficult to reproduceresults in the laboratory for design aids and redesign is sometimes necessary.Models should only be used as one design tool of many.

A Can we extend the design life of an installation by exchanging carbonsteels for Corrosion Resistant Alloys (CRAs)? Can a design for 12 years beextended by 5 years? Once an installation is up and running managers dontwant to take it out of surface.

A Inhibitor availability is a key issue. Life time designs can allow for 2/3 mmcorrosion, if the inhibitor availability is 98%-99%. The inhibitor availability isbeing pushed very hard, especially on unmanned lines and production sites. Itis necessary to demonstrate that you are actually achieving the requiredavailability to back up your corrosion mitigation strategy.

Inhibitor detection is required to monitor its performance and sometimes itsdetection is not effective.


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Presentation Continued

A case study was presented to demonstrate the effect inhibitor on corrosion.A chart depicting the inhibitor availability (ppm) against time (days) with an

overlay of corrosion rate (mm/yr) against time (days) was displayed.

In this case study the inhibitor rate in the period of interest was initially high at200 ppm and there was only a small corrosion rate recorded approximating to0.01 mm/yr. The corrosion team was instructed to reduce the level of inhibitorby half due to the low corrosion rate. The resultant effect observed was arapid rise corrosion rate which accelerated to 0.16 mm/yr over 14 days andcontinued to accelerate. The cost resulting from this reduction in inhibitor wasgreater than if the supply of inhibitor was maintained.

Discussion Period Corrosion Inhibitor Issues

Q (Theirry Chevrot (TC)) For a corrosion rate of 4 mm/yr including pits and adesign for 25 year working life. What inhibitor availability can you estimate?What would be the corrosion allowance e.g. 4-8mm that you would design intoyour pipeline?

A (MJ) We use flow meters on our inhibitor tanks to monitor and measurethe use of inhibitor.

A You need to ensure that your system works

A There is an issue of concern with the systems in place to monitor andmake decisions for new designs.

A (MJ) You have systems in place and need to ensure that your workforceis trained, knowledgeable, and competent to make correct decisions.

A (MS) Need to design in redundancy i.e. two inhibitor feed pumps and runone for a month and then the other to allow time to address maintenanceissues. This reduced potential for inhibitor feed problems, although theyoccasionally occur. As an integrity/corrosion engineer you need to stand upand ensure that the well is shut down until the inhibitor is back online or theconsequences could be very costly. Production will be very against this idea

but it is a necessary action.

A Need online data fed back to the office showing chemical usage.

A Many systems are email capable allowing effective data feedback.

Q (MJ) Are we making progress in this area of concern?


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A From an operation point of view it is necessary to make sure productionbosses understand the issues of inhibitor control and will if in the case of feedloss apply pressure for shut downs.

A (Mette Neilsen (MN)) You can make the operations manager responsiblefor integrity, he is then the only person who can make critical decisions.

Relationship management is the key.

A (MS) You need to develop an integrity management procedure withinvolvement from operations so that the responsibilities of all are known.


Topics for further discussion include;

Weld corrosion

Weld corrosion is a major concern in oil and gas installations. It is a localisedform of corrosion that appears to occur frequently. There is some correlationbetween nickel content in the weld filler and the risk of corrosion. Thishowever, is unpredictable and weld corrosion often occurs without thepresence of nickel.

It is important to understand the welding procedure and how this may affectthe corrosion potential of welds. Correlations have been observed betweenweld temperature and penetration depth. The optimum weld temperature mustbe determined for the weld filler in use to ensure minimum risk of weldcorrosion.

The weld filler must be developed carefully as the integrity of the installationrelies upon good welds. Welding applications include;

Flanges Risers Skids Pipelines and repairs Fittings

It only takes the failure of one weld to cause a major problem.

Discussion Period Weld Corrosion Issues

A (Steve Paterson (SP)) Where you have condensed water in the lineconductivity is often low, the tendency for weld corrosion is low. The use of aninhibitor in these situations may actually enhance weld corrosion. It is possibleto use fillers such as, carbon manganate rather that nickel to try and minimiseweld corrosion.


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There is a clear need to develop more effective weld filler materials and to testinhibitors on the weld filler as well as general pipeline and fitting materials.

A (GW) We have observed that some inhibitors can make weld corrosionworse. You need to design an inhibitor into the whole system to make sure it

works.

A Corrosion inhibition can override the metallurgical effects in weldcorrosion.

Q (Adetutu Fapohunda (AF)) Do you know of any incidents of corrosion inwelds controlled with corrosion inhibitor at 99% availability?

A (TC) Our lab tests have shown this is possible but there has been noevidence in field tests yet.

A (SP) A field with 95% inhibitor availability was brought on, a short bypass

section (FSM) was included with nickel welds and began to corrode. The linewas injected with inhibitor and the corrosion stopped.


Murphys Law of pipeline corrosion;

Corrosion will occur where there is no monitoring,Corrosion monitoring prevents corrosion at that location.

Does heat transfer in the system change the corrosion kinetics anddoes it mater where the corrosion probes and coupons arepositioned?

Discussion Period Monitoring Methods

Q (MJ) Does anyone have experience of how the location of monitoringmethods changes corrosion?

A In our lab, top of the line coupons experienced different corrosion rates to

coupons positioned elsewhere in the line. This could be due to heat transferand it is noticeable that greater difference in corrosion rate occurred incompound probes made from ceramic mixes.

A (MJ) Electrochemical resistance (ER) probes can become coated in wax.This can be an indication of heat transfer problems.

Q SFM can be a less intrusive way of monitoring but are the resultsrepresentative of the system?


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A (TC) In perspective, corrosion monitoring is there to tell us what changesoccur during the life of a field.

We use monitoring to determine if inhibitors work. If they are coated in wax orpositioned incorrectly then there may be problems with your pipeline.

A (MJ) Monitoring is only one piece of information.

A It can only be used as an indicator. It can tell you if corrosion is takingplace but the rate of corrosion information is only relative to the corrosion ratehistory collected of the pipe.

A Laboratory work involving ER probes can allow the rate of corrosion to becalculated. This however needs to be reliable to be trusted for application inthe field.


Intelligent pigs are used to inspect the condition of pipelines in both onshoreand offshore applications. They can be very costly.

There was some pigging data presented by MJ showing some of theinconsistencies that are regularly experienced in pipelines. There were distinctareas in the data that showed correlation between the inspection methodsemployed from MFL, internal UT and external UT, but there also many areaswhere no correlation was present. This suggests that that the inspectionmethods should be used as a guide only.

MFL is a technique often used for prove-ups and has a tendency tounderestimate corrosion compared to UT techniques. The interpretation of thedata collected is difficult and the results hold significant uncertainty.

A chart was presented showing the actual wall loss (mm) against the wall lossmeasured by intelligent pigs (mm). The level of uncertainty was evident fromthis data and it can be concluded that the wall loss measured by pigs 20%accurate for 95% of the time.

The concept of pigs causing pipeline damage and corrosion was introduced.

Disk pigs remove water but have a tendency to smear wax over the

surface of the pipeline. Brush pigs remove wax and corrosion products from the surface of

the pipeline but have the tendency to reopen/reactivate pitting sites.

Discussion Period Corrosion Damage Measurement

Q How do you measure corrosion damage?


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A (MJ) We use UT as our base line measurement and compare over lifetimeof the installation.

Q Why do you believe UT is the most accurate and consistentmeasurement?

A (MJ) It is the technique we have the most control over.

Q Do you use external UT at all?

A (MJ) We understand the limitations in this technique but external UT showconsistency through our orientation and corrosion defects.

We have seen cases where type 1T pits where internal UT shows no pits dueto the orientation of the pit in relation to the pig, but external UT has showedthe defect with great accuracy. Internal MFL is also a good pit detectiontechnique where small deep pits are suspected.

A Internal UT requires a very clean pipeline to be effective.

Q With respect to internal UT data, did you run a baseline prior to collectingdata?

A (MJ) The pipe age needs to be taken into account. This line is 30-40yrsold. The technology wasnt available to run a baseline measurement.

A (SP) A baseline survey can considerably increase the accuracy of MFL.

A (MJ) The MFL technique doesnt measure wall thickness though so is itnecessary to run a baseline. There is no calibration facility with MFL.

UT measures the wall thickness so the data collected is relative and historic.

A (TC) It is always necessary when performing inspections with tools to beconsistent with the analysis. You can only compare data collected in the sameway at the same locations.

A (MS) It is difficult to run a baseline. It largely depends on the piggingtechnology available and the pipeline characteristics. A baseline providesnecessary data to avoid the incorrect conclusions about corrosion being

made.

A It is possible for some pigging contractors to sometimes give incorrectinformation with respect to capabilities of their pigs.

One particular company was consulted on a pipeline design during theconceptual stage and said that the line could be pigged. The design was thenimplemented and the company then claimed that they had not yet built a pigof suitable size!


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Presentation Meeting the Design Intent

Steve Paterson (SP) Head Materials & Corrosion Engineer, Shell UK

It is necessary to adopt a life-cycle approach and avoid projectsavings that increase the operating expenditure.

Consider the effects that process conditions have on selectedmaterials. You should use failure mode analysis to quantify theeffects.

It is necessary to write a full description of materials selectedincluding justification of their selection to allow the purpose and thelimits of the design to be known.

It is necessary to pay attention to the management of change in theproject and progression from the concept to the execution stages.

It is necessary to avoid too much deviation and substitutions fromthe design specification. A procurement strategy must reflect the project risks.

o Identify key areas and focus surveillance activities.o Be aware of slippage creating materials issues.

Be aware of intentional slippage from contractor companies thatforce you to select materials that you are not comfortable with toreach the deadline.

Discussion Period Meeting the Design Intent

A (MS) I have had experience with all the above comments.

A In big organisations, it is possible to loose the key design concept behindspecific materials selection.

A (SP) It is frustrating when contractors allow projects to slip when you haveplaced all the possible safeguards on your side of the project and ordereditems well in advance.

Q (MJ) Is the integrity manager of Shell responsible for projects?

A (SP) It is the responsibility of the project manager to ensure that theproject meets the integrity intent.

Q (MJ) A dedicated integrity manager will have more control/power to makedecisions.A The concept of an integrity manager is to provide integrity managementintegration to projects.


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An integrity management document can give assurance but if you want 100%implementation then a new integrity management system must be adopted.

A In the last two years we have established an integrity assurance engineerposition. We now have much more control over the capture of problems andhow they are addressed.

A (Ron Hewson (RH)) Some clients have systems in place where theproject manager of an installation becomes the operations manager for thatinstallation for the first 3yrs of operation.

A (MS) We have experienced that process it is very effective.

A (RH) The Contractors involved work in an alliance mode and haveinfluence throughout the project.

A (SP) That was a good concept in the past but is now out of fashion. It isdifficult to maintain alliance and can be very costly.


Maintaining the external fabric of an installation also a big challenge, itprovides a bit threat to integrity;

Must ensure that the requirement for insulation is addressed earlyin the design stage and the design is tailored to the needs of theinsulation.

Must enforce good quality of finish on all components and use

appropriate methods of insulation and coatings. Must develop inspections techniques and strategies as part of the

design stage.

Discussion Period Coatings and Insulation Issues

Q (MS) does anybody have any comments or experiences with insulationissues?

A (Graham Gibb (GG)) I have seen CUI and TSA coatings completely

corroded through. The reason for this is unknown so it is worth checking allyour systems.

A (SP) TSA needs to be applied properly.

A (GG) The operators comment was What do you expect; you wouldntexpect it to be immune forever!Is TSA really suitable for these applications?


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A (MS) TSA can be applied differently and its performance depends uponthe standard of its application. Applied to a good standard and it will last 25-30yrs.

A (TC) The lifetime of TSA is dependent upon its location and who applied

it.


There is a number of failure mechanisms in steels used today and one ofmajor concern is stress corrosion cracking particularly at weld sites. There isnow a version of 13%Cr alloy that is suitable for welding and provides verygood resistance to cracking.

The mechanism for Hydrogen Induced Stress Cracking (HISC) is largelyunderstood and mitigation can be achieved by the use of cladding spools.

Failures of lean grade steels due to cracking and not well understood but it ispossible to use a rich grade applied with PWHT.

Duplex stainless steels, 22%Cr and 25%Cr can be applied to short pipesections but is expensive. Failures of Duplex have questioned its use insubsea applications.

It is possible to use Corrosion Resistant Alloy (CRA) to clad stainless steel.

Failures of Asgard and Thunderhorse were attributable to stressed CRA

components.

It is necessary to ensure that welding is carried out to specific standardsEEMUA194 and that a high quality coating is applied to reduce the risk offailure.

It is also necessary to be very clear about the design choice for weld materialand any coatings applied.

Discussion Period Use of Corrosion Resistant Alloys

Q (Gordon Rowan (GR)) What about down-hole materials selection for wellsand well tubulars?

A (SP) you need to design to the specific application.

There is an ASI for the use Alloy 718. Failures of this material have shownthat a very good surface quality is required.


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A (MJ) Metallurgists and materials scientists have developed many alloysthat are used down for down-hole applications to the top-side processes.Some of which have been developed for their weldability.

Q Does anyone have any experience with cladded carbon welds and theissues with monitoring their condition?

A (SP) If it a chemically bonded and not mechanical then inspection ofbonds is possible. It is difficult to inspect the quality of mechanical attachment.

Q Are there any precautions that we should know about in using 65 carbonsteel?

A There have been some concerns with its use on ocean liners.


It is important to ensure that the design is completed with the use ofappropriate standards and that the standards are presented with the design toreflect their importance.

There are several relevant materials selection standards

EEMUA 194. NORSOK M-001. ISO 15156. ISO 13628-1 Subsea ready.

New ISO NP19910 (proposed). Company specific standards.

Discussion Period Design Standards

Q Is a company specific standard specific to one location or is it applicableto all application round the world?

A (SP) It is applicable to the region that you are working in.

A BP uses a global standard system and they are beginning to adopt sitespecific standards for each location.

There are concerns with the looseness of their application. They appear to bevery conservative.

It is a big challenge to make global standards usable.


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Presentation Materials Selection and Integrity Managementin the Design Stage

Thierry Chevrot (TC) Corrosion Specialist, Total

As corrosion engineers we are not doing our jobs correctly!

If we were then the production managers etc would work with us!

Corrosion monitoring - Why do we get it wrong?

We need to address the need to monitor correctly and use the data collectedeffectively.

There is a false sense of security provided when lots of monitoring isconducted. Many monitoring schemes are not very effective and dont providethe correct picture of integrity management performance.

What can we do?

Our corrosion monitoring philosophys need lots of development. They shouldbe addressed before/during the design stage and throughout the project.

We need to ensure that the correct monitoring locations are selected and thatwe do not to deviate from the design.

The pipeline engineer should be given ownership during the engineeringphase and should work full time on the project, briefed on the monitoringrequirements and by sufficiently trained. The equipment requirements have to

be made clear in order to achieve our goals.

Discussion Period Inspection Issues

Q Are corrosion engineers becoming more involved in the design stage?

A (TC) This is the case in our company. The pipeline inspectors arebecoming involved with pipeline layouts and probe positioning etc. Thishowever, is only for large projects and they tend not to get involved in smallerprojects.

Progression in this area is only possible if we as corrosion engineers explainand justify the importance of these considerations.

A (Cliff Johnson (CJ)) It is necessary to explain to managers what you do ascorrosion engineers. You need to convince managers that corrosionmanagement is part of asset management and you should justify it financially.


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Q (SP) Why design corrosion coupons which need to be taken out of theline for inspection. Do these reduce the integrity of the pipeline?

A (MJ) Corrosion coupons provide a baseline measurement.

Q (TC) Do coupons disrupt the flow?

A (MS) you can get flush mounted coupons that dont disrupt the flow.

A (TC) They need to be correctly placed to provide a representative picturein the pipeline.

A (MS) We need to design a more effective system to monitor corrosion inour processes.


There are problems associated with field developments of subsea systemsthat become very technical. We often dont have the technology to cope withthe complexity of these systems and need to adopt a transversal approachthat allows us to understand;

The mixes of metallurgies, Corrosion mechanisms/cathodic protection, Thermal insulation, Erosion due to sand and other solids, Sealed protection boxes.

Failures offshore are often very costly. We have adopted a tendency to learnfrom our failures rather than to ensure our designs will work. Many failures arecaused by the failure of small components such as bolts. There seems to be alack of adequate easy solutions.

Discussion Period

A We need to find time and a systematic way of looking at the projectdesign to ensure it is correct.

A It is very important to consider fully the design of spools and coupons thatare easy to use but will provide the relevant data.

It is easy to fall in to the traps of materials selection for effective design. Atypical example is the selection of steel which is hot galvanised vs. steel thatis zinc coated. The corrosion performance will differ significantly betweenthese two materials. If you select hot galvanised steel then make sure thesteel you receive is hot galvanised!


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Session 2: 13.30-15.30 Causes of Corrosion.

Session Managers:-

Egil Gulbrandsen (EG) - Institute for Energy Technology, Materials andCorrosion Technology.

George Winning (GW) - Integrity Team Manager, Clariant Oil Services.

Presentation Causes of Corrosion

Srdjan Nesic (SN) Professor, Ohio University.

Mechanism of sweet corrosion.

The overall reaction:

Fe + CO2 + H2O FeCO3+ H2

Anodic reaction:

FeFe2++ 2e-

Cathodic reaction:

CO2+ H2O H2CO3H2CO3H

++ HCO3

H++ e- H2

Following de Waard & Milliams mechanism

H2CO3+ e- H2+ HCO

-

In sweet corrosion the pH can be altered by changing the concentration of H+.The carbonic reaction however is independent upon pH so is more difficult tocontrol.

If the concentrations of carbonic acid and dissolved iron are correct thenFeCO3will precipitate on the solid iron surface and for a protective film at thesteel surface. Iron carbonate films can protect against CO2corrosion.

Mechanism of organic acid corrosion

Organic acids such as acetic acid are very corrosive.



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Ac = AcetateFe + 2HAcFe(Ac)2+ H2

Anodic reaction:

FeFe2++ 2e-

Cathodic reaction:

HAcH++ Ac-

H++ e- H2HAc + e- H2+ Ac

-

The binding between H+and Acetate is the corrosion causing step in organicacid corrosion. The corrosion potential is also more powerful than the pHsuggests which shows similarities with CO2corrosion.

Control of the pH in this mechanism will proved some control over the

corrosion caused by organic acids. Corrosion due to organic acids is also veryflow dependent.

Discussion period CO2and Organic Acid Corrosion Mechanisms

Q Does the film caused in the acetic acid reaction interact with films of ironcarbonate protecting the steel surface?

A (SN) Organic acids are very corrosive, they tend to dig under ironcarbonate films causing them to peel off.

Q Are organic acids and CO2behind pitting?

A They have been related to severe local attack. It is possible for 100ppm ofacetic acid to produce a corrosion rate of 50mm/yr. it is necessary to ensurethe measurement of acetic acid is accurate for your system.

Q (SN) How many here today are measuring acetic acid concentration?

How many are monitoring in such a way that acetic acid measurement isaccurate?

Q (GW) Analysis is a fundamental issue. Is there a standard procedure inyour companies?

A (TC) The first step is to check whether your water analysis is correct andrepresentative of your systems and consistent with the pH.

A (SN) As far as I know there is no standard of water analysis technique.


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A (Peter Allison (PA) API 45 does cover water analysis. Organic acids arealso food sources for bacteria so DTI have issued a sampling procedure forthe North Sea sector.

A (SN) Organic acids like interfaces and are often able to interact withoil/water/inhibitor interfaces in a multifaceted reaction.

A (Sadie McNeil (SM)) Corrosion inhibitor interaction with organic acids canenhance the corrosion inhibitor.

A (SP) The corrosion inhibitor that we use was preventing acetic acidcorrosion in the field.

A (MJ) Localised corrosion occurs in the presence of acetic acid in our fieldand we use it as a criterion for inhibitor selection and performance. Bacteria inour water samples can rapidly consume any acetic acid present.

Organic acids can change the pH, surface properties, water/oil mix properties

and the inhibitor action.

It is necessary to control the organic acid concentration and the butyric acidconcentrations. If a molar concentration is maintained then a good estimationof the corrosion rate can be made.

A (EG) Organic acids corrode more strongly in low temperature systems.

Presentation continued

Sour corrosion (H2S) mechanism

When H2S is not full dissociated the mechanism is not too dissimilar to themechanisms or CO2 and organic acid corrosion.


Fe + H2SFeS + H2

Anodic reaction:

FeFe2++ 2e-

Cathodic reactionH2SH

++ HS-H++e- H2H2S + e

- H2+ HS-

The reaction scheme for H2S corrosion is nut fully understood and thismechanism only proposes a possible pathway.


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Sulphur is very reactive and forms iron sulphide very rapidly at the surface ofthe steel.

The Fe2+ion in the steel are able to diffuse easily through the iron sulphide toform layers of sulphide at the surface of the steel. H2S is able to diffusethrough the formed layers to the iron/iron sulphide interface and cause

ruptures and cracking to occur in the film formations. This allows furtherpenetration of H2S and significant corrosion occurs.

Iron sulphide films have been attributable to some degree of corrosionprotection but due to their often fragile and porous structure they can oftenbreak away from the surface leaving corrosion sites exposed. It is possible forfilm thicknesses to range from 10-100m thick.

The film formation is the main difference between the H2S mechanism andtwo mechanisms previously discussed. The controlling factors aretemperature and H2S concentration.

Discussion Period H2S Corrosion Mechanism

A CO2corrosion initially dominates over H2S until the concentration of H2Sbecomes large from 10-1000ppm. At small concentrations of H2S there CO2corrosion mechanism is suppressed.

Q Is the surface exposed to the oxygen where sulphide corrosion isgreatest?

A Where sufficient levels of oxygen are available ignition of the sulphide film

is possible.

A (SP) the conventional thought is that the sulphide films are very adherent,this is however not always the case.

A (SN) Most of the protective film cases occur in low concentrations of H2S.When the concentration is increased, elemental sulphur can be releasedforming detrimental films. The reason behind this is not known.

Q Have you done any studies to quantify H2S protection capabilities?

A (SN) Burt Potts was of characterising CO2/H2S ratio is the best way of

quantification. You should aim for a 1:1 ratio to achieve the lowest corrosionrate. There is however, not much understanding behind this.

Q How strong is the bond between a sulphide film and the metal surfaceand what are the characteristics of any interactions?

A Some sulphide films have semi-conductor properties and form bondsbetween the film and the metal that can be very tight. The strength is howeverdifficult to quantify.


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Q (GW) When do metallurgists get involved in the design of yourprocesses?

A (DJH) Communication with metallurgists is fairly early in the designprocesses. Top-side and subsea modifications are also verified bymetallurgists.

Q (GW) Are design of cladding and coatings considered by yourmetallurgists?

A They are considered to be general design issues.

In the case of CRAs what is the definition of material failure?

CRAs are designed to operate in a specific environmental window. We needto ask if we are managing the change effectively and whether we are tying tooperate outside the envelope for these materials.

Q Are there any identifiers for the causes of CRA failures?

A There are but the message sometimes doesnt get through to the relevantpeople soon enough. It appears that contractors are not very good at passingon the correct messages quickly.

Q (Reg Simpson (RS)) Can the proliferation of contractors investing inoverlay equipment cause a problem?

A CRAs generally withstand corrosion but the melt zone in between thecladding and the CRA can cause phases that are brittle and susceptible tohydrogen embrittlement. It is important to never design the interface to carryload, failure is common in these situations.

A Hot welding can drive the hydrogen out but some deep assets open upallowing hydrogen embrittlement.

A Shell published the information they learnt following the Shearwaterfailures and collaborated with Total and BP to understand the failuremechanisms.

Material testing is the first essential step and from this we no longer useSS316 in instrument tubing.

Q (SP) Why do we still use SS316?

A (TC) We have banned 316 from our designs but contractors could notsupply sufficient fittings in 904. Tubing is now made from 904 and fittings areallowed in 316. However, some of the 904 supplied to us has been of poorquality.


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Presentation Corrosion under Insulation (CUI)

Don Harrop (DH) BP Exploration Operating Co.

Water ponds under insulation can form where pipeline designs have not beenthoroughly thought out. These traps can be the cause of significant corrosion.Local concentrations of aggressive components such as chlorides canbecome very high.

Inspection of CUI becomes a problem as it is difficult to determine a startingpoint. Techniques such as infrared scanning can be employed to locate waterbuild up but this does not always work in complex systems.

It is possible to use the CUI risk pyramid which provides a structure foreffective inspection. It is however generally necessary to develop a tightinspection regime to determine the condition of the insulation and thepipework beneath it.

The management of systems and insulation needs be effective for a longlasting installation especially if there is a possibility for extended usage. Theinspection of insulation can be very time consuming and costly.

There an industrial forum setup for the discussion on CUI by John Thirkettle.

There are some serious issues arising from CUI especially on passive fireprotection installations.

Discussion Period - CUI

Q What is peoples experience of detecting CUI?

A (SP) We are experience continual problems on Shearwater. CUI on thecontactor column was detected and we now use a strategic system for CUIdetection. A risk matrix was developed where those items flagged as mediumor high risk are manually checked.

A - Stripping and replacing insulation however can be the cause of corrosion.You should be careful not to replace original insulation with inferior products.

Q (AD) Are we managing CUI properly? My experience allows me to saythat there is little evidence of maintenance and that often insulation isreplaced and not sealed. The operations system doesnt always coverinsulations fitting.A (TC) The only was to ensure against corrosion is to remove and replaceinsulation. After 10yrs this should be done whatever the state of the insulationand pipework.


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A (MJ) In the arctic area, polyurethane insulation is fitted manually andinspected continuously. 10000-15000 insulations are checked every year.

Q (MJ) Has anyone had experience of polyurethane insulation failing?

A - No experiences offered!

A (DH) It is about getting the resources necessary to manage the problem,this is a major task.

Q (DH) Do we really need insulation? Can personnel protection be sought inother ways?

A (MJ) Expanded metal can be used for insulation but can be seen as asafety issue.

A (SP) Insulation reduces noise driven by HSE and not necessarily forthermal insulation.

Presentation Prediction Success

Srdjan Nesic (SN) Professor, Ohio University.

The prediction model developed by de Waard & Milliams has been used withsome success but is limited by the knowledge level and data built into themodel.

The accuracy of models is dependent on the accuracy of the data used intheir development and the level of knowledge built into them.

Operators using models should be fully trained in their use and in theinterpretation of the data collected. The limitations of any model should alsobe made very clear to all those using it.

Discussion Period Corrosion Prediction

Q Does the de waard & Milliams model take into account the build-up of ironcarbonate films?

A (SN) The key issue is the pH, if the pH is in a certain range then there willbe no build-up of film. The pH must be controlled.

Q (Will Durnie (WD)) Can you explain the term mechanistic model?A (SN) The parameters in mechanistic models for corrosion prediction havemeaning such as Dofor the diffusion coefficient. Empirical models aredeveloped from data and the parameters are coefficients e.g. a, b, c whichhave no direct meaning to the corrosion rate.


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Q (Neil Bretherton (NB)) When testing inhibitors, film domination occurs at50 -60C. In pre-scaled surfaces are models important for inhibitor selection?

A (SN) Sometimes interference of scale/inhibitor occurs where scale andinhibitor both compete for space on the metal surface. We can not predict the

strength of interaction from general knowledge.

A (EG) This is a very poorly understood area.

Q (DH) Cassandra is a BP model for corrosion prediction. We arecommonly asked how to set up arrays in the Cassandra model in excel. Howmuch information are people using to run these models?

A (SN) We need to capture all of what we know within models.


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Session 3: 16.00-18.00 Design of CorrosionMitigation Strategies.

Session Managers:-

Peter Allison (PA) OFC Technical Services Ltd.Karen Christie (KC) Commercial Microbiology Ltd.

Presentation Design of Corrosion Mitigation Strategies

Peter Allison (PA) OFC Technical Services Ltd.

Alternative strategieso Balance capital costs vs. operational costso Use of corrosion resistant materials vs. corrosion inhibitor.o Can you mitigate corrosion by changing the operating

procedures?o Use Life cycle analysis of system for optimisation.o Adopt different strategies for different times in project life.

Internal corrosion strategies.o Need to consider the consequences and likelihood of failure.

Other flow assurance influences.o Production chemistry

Scale/hydrate/wax control.o

Usually one issue is more of a control challenge than others-this is a driver for strategy choice.

Discussion Period

Q (GW) Do limitation of availability of carbon steels force selection of CRA?

A (PA) Depends on the operations/operators solutions available.

A (TC) Sometimes pushed into solutions that are not optimal but necessary.

A (MJ) We have to sometimes take the options that are available due to

cost constraints.

Q (PA) Why take the option of inhibiting corrosion rather than using CRAs?

A (TC) If you have a large field with 200+ wells then material selection isimportant. It could be more cost effective to use an inhibitor. It is easier toinvest in CRAs for smaller projects.


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Presentation Strategy Identification and Implementation

Dan Kirkwood (DK) Oceaneering International.

According to the Hoar Report 1971 the cost of corrosion in the UK was3%GDP. 30yrs later the cost of corrosion according to the DTI 2000 is3%GDP.

The Hoar Report identifies the need to;

o Increase education in corrosion and corrosion protection.o Increase awareness of the hazards of corrosion protection.

It was identified that corrosion mitigation it must be practical!

The importance of painters on installations was highlighted and examples

made with the Golden Gate Bridge. The challenge on installations today isaccess!

There are several top corrosion issues 2007

Source CMWG March 2007.

Boeing Vertol Chinook incident 6 Nov. 1986.

o Route cause Corrosion of gearbox.o A galvanic cell formed in a crevice within the gearbox mechanics

and the component failed due to fatigue cracking.

Synchronisation was lost and the helicopter blades collided.

2ndTay Rail Bridge 120thbirthday opened in June 1887.

o Question Are the materials that we think we are working withactually the materials we think they are?

o Water trapped in the construction bars measured at pH 3.5.There is a 30% lost in thickness at the 6oclock position in thecross beams over 100 years time period.

o Need to make sure the design for corrosion mitigation ispractical and realistic Drilling drain holes in the cross bars willsignificantly compromise integrity of the structure!

Offshore installation with corrosion rate of 12.5mpy Internal corrosion the rogue pit!

o Analysis showed insignificant metal loss (Net) one pit causedthe failure!

o Micro-colonising containing sulphate and nitrate reducers. Thisparticular bug causes harm to humans.


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We need universities, industries and research institutes to research industrialtopics.

How do we ensure that we understand foreseeable future corrosion issues?

Pro-activity in identification:-

Need to face consistency issues How confident are we of these outcomes?

Issues for the conference to consider:-

What can be done to better capture corrosion considerations inpredicted work?

What can be done to influence improvements?

Presentation Design of corrosion Mitigation Strategies

Ron Hewson (RH) Asset Integrity Consultant, ABB Engineering Services.

Industry challenges and trends

o Issues with age profileso Repeating mistakeso Too much reliance on the black box!

Life cycle is very important

o Key principles Materials selection, construction, operations. Maintenance, inspection and communications. All should incorporate failure investigation.

Discussion Period Corrosion Mitigation Strategies

Q What is the subject matter of today?

A Corrosion mitigation.

Need to understand life cycle as a whole company or team.

Q (RH) How do you get to the information back into the system?


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A (SN) There are procedures in place.

A (GW) There seems to be a missing link in the chain!

Q (RH) I think communication is a problem between companies andcontractors.

Training is very important.

A Quality of information is important, needs to be clear and accurate.

Q (RH) How do you ensure correct accurate information is fed back?

A We need to work with operators.

A (TC) Route causes often found but reporting can be hard when people arebusy. Systems in place are very complex.

A (RH) We need to take the time to communicate correctly.

A (MS) NTI is an online question and answer database for addressingissues in industry. The SPE also have an online forum for industrial issues.


Examples of corrosion problems on installations:

E.g. cable trays that have been replaced but instead of being welded on to thetray hangers they were welded onto the integral structure of the pipeline andgalvanic corrosion caused leakage. This was identified as a managementchange issue.

Need to be aware of fatigue factors and ensure that people understand thatthe message of fatigue needs to be addressed early so the message needs tobe sent early and not when the failure has occurred.

Interpretation of data should be done by educated personnel or operators whoare trained. This can increase the life of components by 4xs.

Integrity managemento Competent peopleo Reliable assetso Effective systemso Preventative maintenanceo Driving with care(operators)o Inspection (routine)o Flowing legislative guidelineso Corrective maintenance.


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Discussion topics integrity management tools

Discussion Period Integrity Management

Q What is the difference between vulnerability and critically?

A Vulnerability relates to the probability of a failure happening.

Critically relates to the measure of importance of an item to the process.

A Fundamentally it doesnt matter as long as definitions are clear in theprocess.

RBI Identifying, analysing, inspecting, collection of data, and reviewing thedata collected.

Environmental change review as necessary.

Safety critical is not a clear definition needs to be clearly defined.

A Safety critical includes items that can cause harm to personnel or people.

Lets not confuse people about definitions.

Safe and economic asset life depends on attention to asset care throughoutits lifetime.

Design correctly Operate within design parameters Inspect regularly Maintain.

Need to use experience, best practice, education and training.

Q The integrity management concept is still fresh for industry, to strengthenthis concept we need to put rules in place and make individuals accountablein the workplace.

An asset manager should be responsible for the integrity of his assets. He

should be able to cascade information easily to lower tiers in the system.

Q (RH) Who ends up in court? Who does asset manager answer to?

A The whole group is responsible.

Q (RH) All should be involved in integrity management including the CEO?

Need to have asset manager clear on responsibilities.


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A (AD) You need to sell corrosion management to senior management!

Q When putting strategies together, do people offshore understand whystrategies are written i.e. continual chemical injection?

A (GW) Need to take strategy ideas to the people who operate them.

Q Isnt that our jobs? Why do we develop strategies and then notcommunicate them to the people doing the job!

A Communication is the key.

Q Why do we feel that we know what happens in the field? We need to usethe procedures that are actually used in the field and write strategies that workaround that.

A We dont have answers to all the issues.

A Smaller independents have CE that spends time offshore to increaseawareness.

Q How do you stop operators walking around on insulation?

A You need to be offshore working with operators they dont want theirinstallations to fail either.

A (Cliff Johnson) We need to talk in the operators terms Why operationswork the way they do? We need to use their knowledge to address thechallenge.

The NACE website will have information addressing issues in the next 6-12months.

A (SN) Need to educate new corrosion engineers. Educatingoperators/technicians in not the key, there needs to be future plans to ensurepeople are effectively trained.

A Integrity requires the identification of clear roles. Operators own integrityprogram and operations should take personal safety on board. They need tounderstand the issues for a step change to occur.

A Operators need issues to be explained and it must benefit them for it towork.

A (SM) Samples from potable water are taken every two days. Corrosionsamples are taken every 2 weeks!

Q Does everyone agree that corrosion awareness must be increased?


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A It is done to a limited extent UMIST currently offers the onlypostgraduate course for corrosion engineers. Hence the UMIST Mafia!

There are difficulties in recruiting experienced people. They tend to demandhigher salaries.

Q (RH) We need to address these problems. What are we doing aboutthem?

A (AD) We ask about recruitment when we go on site and the answer issurprising. Apprentice schemes were excellent but they havent occurred inabout 20 yrs.

Maritime graduates are being used to great effect in the North Sea.

A In Abu Dhabi, graduates are selected on their performance and the bestare recruited and then trained up in corrosion engineering.

A (SP) In 24 recent recruits we have 5 graduates. Experienced engineershave been coached in knowledge transfer to young engineers. Education isnot just about training, learning is the key. You retain more knowledge bydoing so we implement discussions.

We like to employ young enthusiastic motivated people. We have in housetraining facilities to increase corrosion knowledge.

A (TC) Training can be done in house very effectively. This is a world widepolicy of ours.

Recruitment of engineers from our contractor companies is now banned in ourcompany. We now tend to recruit 25yr olds and train them in corrosion.

A (SN) I think some basic knowledge of corrosion is required in order toperform well. Good awareness and sensitivity to the subject will allow youngengineers to perform well in time.

Q (GW) how do you teach a subject if people dont want to learn it?

A (GW) Close of session comments:-

Communication is the key factor in a successful future.


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Day Two Wednesday 21stJune 2007

Session 4: 08.30-12.30 Implementation of CorrosionMitigation Strategies.

Session Managers:-

Alyn Jenkins (AJ) Corrosion Team Leader, M-I SWAC.OStephen Maxwell (SM) Commercial Microbiology Ltd.Derek McNaughton (DM) Corrosion Engineer, Oceaneering International.

Presentation Corrosion Mitigation Chemical Selection andTreatment

Mohsen Achour (MA) Staff Engineer, ConocoPhillips.

Corrosion inhibitor selection, how do we do it?

Challenges:

How do we select the correct inhibitor? How much of it should we use? How should it be applied, batch or continuous? How do we know its working?

If there is uncertainty in any of these 4 steps then failure will occur!

Need to understand the system to be treated. This is not trivial. We donot always fully know the system. We often only have a best guess.This is easier on existing fields where data can be used.

Need to work with more than one vendor- time consuming. Provide field fluids for testing easy to say. Perform inhibitor testing in house or assign a lab to perform it for you. Choose appropriate tests to choose correct inhibitor.

Discussion Period How Do We Select the Correct Inhibitor?

A We find that our understanding of the system is ok but we are often forcedto compromise therefore the performance is reduced. The productperformance is often a minor part of the product development.

A It is easy to get a chemical that works but difficult to get one that iscompatible with the other constraints.


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Q (GW) The complexity of testing has increased recently to under deposittesting, weld testing, etc. Does anybody have any concepts for testing in thefuture?

A (MJ) We seem to put more constraints on chemicals. In Sub-sea facilities,we now require hydrate testing. We can start with a much smaller pool of

chemicals. How to select current inhibitor? Start with water soluble vs. oilsoluble. What is implied be this terminology? We are interested in the activesonly, solubility going to affect performance greatly?

A (GW) Solubility is vague. Still large amount of inhibitor in the interface, thisis not good terminology.

Q The majority of testing looks for general corrosion. What tests are therefor localised corrosion?

A Short term testing is required for general corrosion whilst long term testingis required for pitting corrosion.

Q Do you partition test for inhibitors?

A Partitioning is key for inhibitor performance.

Q 1) Is there a feel for the test time for products?2) Where are we in terms of the best product development wise?

A Is there change in the future? The conditions of the reservoirs arebecoming worse (sour). We dont have any choice but to change thechemistry.

A We are limited to the DTI environmental goal posts. There is a blanketwide warning on surfactant use!

Q Do green products mean lower performance?

A I dont think so we need to change but the industry wont accept lowerperformance.

A There are 2 markets. The US is an easier market for chemicaldevelopment. UK market is more difficult is it is costly to register newchemistries. There are more environmental rules in the North Sea.

Q What R&D is required to development of chemistry in the future?

What is the need for new chemicals and how are they best tested?

A We need to know the rules and CFAST regulations for productdevelopment need guidance for the development of realistic systems. It isdifficult to react with out them.


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Q Lab tests are good how can you develop for the field though?

Q New chemistries are expensive. How do you sell a better performingmore expensive product? Operators need to know that there is a costinvolved.

Q Can we come to an agreement on the test procedure, i.e. pre-corroded,test equipment etc?


How much inhibitor should we use?

Adopt a conservative approach money, availability. Take vendors advice depends on what you are doing. Need to find

optimum concentration. Optimise injection rate take into account solids present, partitioning,

scale etc. Rely on corrosion monitoring/lab testing How confident are you with

the results? Vary injection rate operation conditions can change. Adjust based on residual analysis how do you correlate information

from vendor and process?

Discussion Period - How much inhibitor should we use?

Q Our corrosion problem occurs near the injection points. Is this due to thelimit of the injector and concentration of the inhibitor?

A Most inhibitors are very corrosive if injected at 100% concentration.Corrosion at injection points is a symptom if this.

Q Sometimes pumps fail during our normal injection strategies. Wegenerally have to introduce more chemical. Does anybody know why thisoccurs?

A You need to inject through a quill into the turbulent areas of the line.Inhibitor can fall out of gas streams in laminar flow.

Q How much should be injected? How does the corrosion rate correlate withthe amount of inhibitor injected? Is it necessary to conduct field studies? As avendor, we should follow up our applications in the field more often to gainsome correlation between lab and field data.

A (DH) There are often correlation problems between lab and field data. It isnot always possible to conduct field tests and optimisation in the field is


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generally only done if you are lucky with budgets and time. Residual Analysis(RA) is a very dangerous technique as it is a low confidence technique.

A You cant trust the numbers from RA but it can be used for qualitativeanalysis.

A (DH) You have to put more effort into monitoring and developing therequirements so that the correct application rate is used.

Q (MJ) RA is important. We need an understanding of where the activesend up and RA provides an indication tool. There are issues related to RAwhen solids are present but loop testing can be developed to determine if theactives are being held in the oil/water interface or are being used in corrosioninhibition.

Q If the surface of a line is clean then the demand for inhibitor in the systemwill be at the surface. If in the field the line is not clean then the inhibitor maybecome located in the interface.

It is not recommended as a sole technique but if it is used you must ensurethat the corrosion rate and the residuals correlate.

Q (DH) RA from day one is useful to build up a history of the system whenused in combination with other techniques.

It is necessary to use high quantities of chemical throughout the life time if thesystem is of high flow.

Q (MJ) These techniques are easy in sweet systems but how do we copewith sour systems where corrosion products form high surface areas andsolids in suspension?

A (MA) Run corrosion tests on brine. Probes need to be developed for soursystems.

A Need to conduct long term tests for detection of localised corrosion.

A Need to look at inhibitor availability aqueous testing for partitioning. Theresults of some of our testing show that an availability of 95% returns acorrosion rate of 1% thickness per year. This is not acceptable.

500ppm inhibitor can be used to provide some protection against 20% H2Ssystem.

Typically need 100ppm for preferential weld corrosion but it is difficult totranslate this to field applications.

Q (GW) Need 500ppm in water to combat partitioning in the oil phase.


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Q (SN) Testing on partitioning in conservative. Oil coats the surface withinhibitor. Inhibitor mostly in the oil phase can still perform very well testingfor partitioning can be misleading.

Q Could the oil it self inhibit corrosion?

Q Is there an inhibition strategy document in place?

A An oil soluble inhibitor at 90% water cut would be the wrong decision. Theinhibitor selection needs to be based on the system requirements.

A We measure a benchmark and then try to maintain performance withinthat.

A Need to check the system requirements regularly operator needs toperform water-cut tests and deploy the chemical with respect to the results.

A You cant hand responsibility to vendor. The operator is responsible for

deploying the correct levels of chemical.

A Responsibility of corrosion manager. If there is a change in the oil/watercut they should address the options with the vendor. It is a team effort.

A It gets complicated when there is many wells each behaving differently.You cant deploy the same in each.

Q (SN) Lab tests show that inhibitor in multiphase systems can change thephase mix from oil wetting to water wetting. This can increase the inhibition.Does anyone test for this?

A We test using inhibitor free oil from field.

A Only need to inject ppm oil levels into water to observe a significantchange in performance.

A Oil wetting for inhibitor testing can be misleading especially in gas wells.


How should inhibitor be applied?

Batch - What volume, frequency? Continuous Is it getting to the surface? Mixing Do emulsions form? What are the water/oil solubility

characteristics? Persistency film removal by pigs.


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Corrosion & Integrity Mgmt

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