ri scales

The Energy Institute

Corrosion Management Working Group

Project S 911 Development of Guidelines for the management of external coatings

Date: 16th November 2011 Venue: Coatings Task Force Workshop - OGP Office, London

Guidelines for the management of external coatings

Guideline aims to assist industry to better manage the maintenance of external coatings for offshore installations

An industry reference document to fostering a common cross industry understanding of what is involved in todays practice.

Improve efficiencies Good practice document for possible referencing within contracts Compiled for UK North Sea but can apply internationally Builds on EI publications instigated by the CMWG:

Guidance for corrosion management in oil and gas production and processing

External corrosion awareness handbook

Guidelines for the management of external coatingsContents

Foreword

Acknowledgements

1. Introduction

2. Management systems

3. Survey & Inspection

4. Assessment criteria & reporting

5. Development of work scopes

6. Implementation

7. Monitoring & improving performance

8. Data management

Annexes:A. ReferencesB. Abbreviations & GlossaryC. CompetencyD. Surface preparation assuranceE. Key performance indicatorsF. Corrosion degradation scalesG. Generic coating typesH. CLAW RegulationsJ. Survey template examplesK. CBA example

Guidelines for the management of external coatings for corrosion protection

Corporate safety

performance standards:Maintain

equipment

Equipment integrity Hydrocarbon

Containment Structural

integrity:

Inspect and assess condition

Approve scope of

work

All relevant components to be identified & effectively maintained: Control of corrosion Routine survey/inspection Coatings remediation Continuous review

Estimate resource requirements

Coatings remediation scope Mobilisation & ancillary

costs

Corporate budgets Adequacy of scope of work

Yes

No

Identify all elements protected by external coatings

Inspection programmes FM planning

Key activities of an external coating management process


Key activities of an external coating management process (contd.)

Update CM database &

MMS

Risk assessoutstanding

scopes

Generate annual FM

report

Determine any mitigating control

measures

Issue scope of work to

contractor

Compile work packs Plan Implement Inspect & report

Reporting Scope completion KPI criteria Outstanding works


Historical approaches: Fabric maintenance geared toward initial de-commissioning date

determined at start of development.

Economics based upon reservoir knowledge and at the time Changes in technology, satellite field hosting and changes in energy

prices.

Many installations are now in life extension mode Significant coatings maintenance backlogs HSE inspections concern for condition of plant


Costs

Where there has been extensive breakdown of the external coating resulting in defects that breach the relevant performance criteria, the costs involved in identifying, mitigating and/or replacing equipment can be significant.

Experience has shown that coating FM costs will increase disproportionately year on year if mitigation to date has been ineffective.

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0 5 10 15 20 25 30

Coatings Maintenance costs escalationCost increase vs. degradation (time)

Initial cost/m2 = 1

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Management policies key elements:

Defining roles and responsibilities Life cycle management approach Performance requirements Implementation of risk based approach Quality assurance Competency Performance targets and use of KPIs Cost management (including costs of not maintaining)

Guidelines for the management of external coatings from corrosion protection

Management through life of field:

Phase 1 Project: Opportunity to properly specify, correct faults

and develop strategy for Phase 2

Phase 2 Operation Tendency for resource constraints Any deferral should have management

approval

Phase 3 run-down to de-commissioning Condition will influence decommissioning date Overall maintenance reduced Vital utilities, escape routes, critical structures

Guidelines for the management of external coatings from corrosion protection

Management strategies:

Operators have differing approaches (generally risk or condition based) Consider the 4 approaches for management of maintenance:

Approach General Features Basis

Reactive Run-to-Fail: 3 5 year design life; component replacement; large campaigns; decommissioning phase.

Risk

Predictive Specialist databases Predictive models 12+ year design life; spot painting

Risk

Preventative Selective local area management; 15+ year design life.

Condition

Reliability centred

Holistic rehabilitation; 20+ year design life. Large campaigns

Condition

However, management of risk should underpin all approaches


Surveying:

Assessment of condition usually by applying the degree of rusting scale as per BS EN ISO 4628 Part 3

Other important information: Descriptive location of the item. Dimensions. Anomalies which will have an accelerating effect on coating breakdown such as

dissimilar metal contact or water pooling. Coating defects such as inter-coat disbondment, uncoated welds etc. Access requirements. Where applicable Insulation condition. Photographs.

Key activity as reports form the basis of scopes of work


Surveying:

Assessment of condition as per BS EN ISO 4628 Part 3 degree of rusting scale


Assessment criteria & reporting:

Use of rusting scale as per BS EN ISO 4628 Part 3Surface condition failure mode

Classification Surface condition

99 Unknown; unobserved

0 Sound coating protection

1 Sound, although aged, coating protection

2 Coating loss; no exposure to substrate

3 Substantial coating loss; no exposed substrate

4Total coating loss; substrate exposed, substrate discoloured; non-ferrous substrate discoloured

5 Substrate corrosion evident; no scale

6Light scale; minimal metal loss (uniform metal loss not easily measurable; early corrosion.

7 Corroded; lightly pitted (early corrosion with or without scale)

8Heavy scale; metal loss evident (uniform metal loss, measureable advanced corrosion.

9Corroded; heavily pitted (advanced corrosion with or without scale)

Other methods rely on verbal description.

(Example shown extends to condition of substrate)



Quantifying substrate damage or deterioration:

When coating has deteriorated beyond say Ri5, substrate damage may need quantifying.

Operators use a variety of methods Category or Criticality.

NDT will be required if significant and especially pre-surface preparation.



Estimating deterioration rates over time:

Coating use of predicted performance curves

Substrate predictions provided in various references such as: BS EN ISO 12944-2: Table 1 - Atmospheric Corrosivitycategories and examples of typical environments.

NDT will be required if significant and especially pre-surface preparation.

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0 1 2 3 4 5

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Max

Mean

Min

Coating performancePaint system X

Ri Value

Area Corrosion Rate (mm/year)

Splash Zone 1.0

Below Cellar Deck 0.3

`Exterior Lower Decks 0.2

Naturally Ventilated Modules 0.1

Pressurised Module Interiors 0.05

Top Deck 0.2

Atmospheric spray zone 0.5


Developing scopes of works

General criteria:

Safety, environmental and commercial impact of failure of the element Overall risk of safety related elements at their current condition BudgetOthers:

Aesthetics; the appearance of the installation is reflected by the general condition of the external coatings.

Planning - The scopes of work for coating maintenance would strongly shape the FM plan.

Potential for deployment of encapsulation (habitats) and dehumidification to allow all year round FM activities.


Basic examples of prioritisation:

Condition based

Risk based

Typical general external coating remedial criteria

Ri No 1 2 3 4 5

Coating maintenance requirements

NoneAesthetics only

Optimum opportunity spot repair

Large scale remediation programme

Element repairs and full coating replacement

Component Target Intervention Maximum Intervention

P1 Structural Ri3/Re5 Cat B Ri5/Re7 Cat B

P1 & P2 Hydrocarbon Pipework Ri2/Re3 Cat B Ri3/Re5 Cat B

P3 Non Safety Critical Ri3/Re5 Cat B Ri5/Re7 Cat B


Using criticality

Probability Potential of occurrence Impact

Has not occurred

Unlikely to occur

several times over 10 years

Several times over 1 year or

recently

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HSEDamage to reputation

Very low Medium High Very high

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Medium High Very high Very high

>

1

0

0

~

2

0

%

>

1

0

0

M

n

One or more fatalities or multiple permanent injuries.

Uncontained spill with severe environmental impact.

Obligation to Regulator

International:Serious

H

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h

Low Medium High Very high

>

2

0

5

10 30 barg

60to80

M

P

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2

Approval by SIE

If unable to take readings under

scale, assign to 3

Wet blast Bristle blaster

Water/utilit

y

10 barg

60 L

N

o

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1Approval by

OIE

Can take readings

adjacent to scale

Wet blast Bristle blaster Needle gun Grinding disc

Consequence

* Worst case of 1st three columns

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External Scaling

No scalingLoose scale

Easily removed

Moderate scaling

Heavy scaling

Heavy scaling

Strongly adherent

D

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F

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Estimated or measured WT

lossNo loss < 1 mm

> 1 2 mm

> 2 mm CA

> CA MAWT + 3

mm

Confidence in WT

Confident accurate min WT

measure-ment

Fairly confident in

readings

Some confidence in readings

Little confidence in readings

No confidence No readings available or

possible

WT Confidence (Probability of failure)

ri scales

Documents

management systems3

coating fm costs

corrosion degradation

relevant performance

development of work

generic coating typesh

fabric maintenance

industry reference document