Ri scales
-
Upload
diaccessltd17172961 -
Category
Documents
-
view
20 -
download
1
description
Transcript of 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
-
Guidelines for the management of external coatings for corrosion protection
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
-
Guidelines for the management of external coatings
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
-
Guidelines for the management of external coatings
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.
0
2
4
6
8
10
12
14
16
18
0 5 10 15 20 25 30
Coatings Maintenance costs escalationCost increase vs. degradation (time)
Initial cost/m2 = 1
C
o
s
t
e
s
c
a
l
a
t
i
o
n
r
a
t
i
o
-
Guidelines for the management of external coatings for corrosion protection
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
-
Guidelines for the management of external coatings for corrosion protection
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
-
Guidelines for the management of external coatings for corrosion protection
Surveying:
Assessment of condition as per BS EN ISO 4628 Part 3 degree of rusting scale
-
Guidelines for the management of external coatings for corrosion protection
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)
-
Guidelines for the management of external coatings for corrosion protection
Assessment criteria & reporting:
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.
-
Guidelines for the management of external coatings for corrosion protection
Assessment criteria & reporting:
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.
0
5
10
15
20
25
0 1 2 3 4 5
Y
e
a
r
s
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
-
Guidelines for the management of external coatings for corrosion protection
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.
-
Guidelines for the management of external coatings for corrosion protection
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
-
Guidelines for the management of external coatings for corrosion protection
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
C
o
s
t
(
M
n
N
P
V
)
1
y
r
.
P
r
o
d
u
c
t
i
o
n
O
P
E
X
/
C
A
P
E
X
HSEDamage to reputation
Very low Medium High Very high
I
m
p
a
c
t
V
e
r
y
h
i
g
h
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
i
g
h
Low Medium High Very high
>
2
0
5
10 30 barg
60to80
M
P
a
r
t
i
a
l
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
n
e
1Approval by
OIE
Can take readings
adjacent to scale
Wet blast Bristle blaster Needle gun Grinding disc
Consequence
* Worst case of 1st three columns
I
n
i
t
i
a
l
i
n
d
i
c
a
t
o
r
External Scaling
No scalingLoose scale
Easily removed
Moderate scaling
Heavy scaling
Heavy scaling
Strongly adherent
D
e
c
i
d
i
n
g
F
a
c
t
o
r
s
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)