-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
1/15
Copyright Talisman Energy (UK) Limited 2004
AN INTRODUCTION TO
ATMOSPHERIC EXTERNAL CORROSION
by
-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
2/15
Copyright Talisman Energy (UK) Limited 2004
INTRODUCTION
1. Corrosion Under Insulation
2. Atmospheric External Corrosion
3. Stress Corrosion Cracking and localised corrosion of stainless steels in chloride environments
4. Galvanic Corrosion
5. Flange Face Corrosion
6. Carbon Dioxide Corrosion
7. Hydrogen Sulphide Corrosion and Cracking
8. Oxygen Corrosion of seawater and water injection systems including internal corrosion of
stainless steels in chloride environments
9. Microbial Influenced Corrosion and Dead Leg Corrosion
10. Weld Corrosion
11. Erosion Corrosion
12. Fatigue and Fretting
-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
3/15
Copyright Talisman Energy (UK) Limited 2004
INTRODUCTION
External Atmospheric Corrosion
A form of oxygen corrosion. The threat is mainly to Carbon Steelbut some corrosion resistant alloys may also be at risk.
Corrosion is a risk wherever the surfaces of structural, process and
mechanical equipment are exposed to aerated water.
Not to be confused with Chloride Pitting and cracking of Corrosion
resistant alloys (covered in the next presentation)
This presentation briefly covers..
Where does it occur?
Locations and items where Atmospheric corrosion is likely to beseen
When does it occur?
When are you likely to see Atmospheric corrosion?
Why does it occur?
What has to happen for Atmospheric corrosion to become aproblem?
What can be done to prevent it?
-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
4/15
Copyright Talisman Energy (UK) Limited 2004
INTRODUCTION
POLICY Talisman seek to assure thecontinued integrity of all sites minimising risk to
personnel, environment and business from thethreat of Atmospheric Corrosion
STRATEGY Fabric maintenance programmes Risk based inspection schemes Planned maintenance routines Corrosion risk assessments
Coating conditions are reported using RI codes inACET and Metacor Fabric Maintenance database.
-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
5/15
Copyright Talisman Energy (UK) Limited 2004
WHERE DOES IT OCCUR?
Areas open to salt water sprayExposed areasDeluge areas
Items at riskVesselsPipework
Risers
Bolts/Flanges
Pipe supportsDeck plating
Stairs/ladders
Handrails
Mesh grating/cable trays
-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
6/15
Copyright Talisman Energy (UK) Limited 2004
WHERE DOES IT OCCUR?
Specific risks Areas atelevated temperatures
Pipework or vessels that operate
between 40o
C and 80o
C are at
high riskWet, hot surfaces
Areas adjacent to insulated
equipment
-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
7/15
Copyright Talisman Energy (UK) Limited 2004
WHERE DOES IT OCCUR?
Specific risks Areas of
trapped water (Crevices)
Pipework supports
Bolts/Flanges Fixings for nameplates
Supports for Stairs/ladders
Cable trays
Any area where water may pool
Underneath coatings Edges of
damaged coatings
-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
8/15
Copyright Talisman Energy (UK) Limited 2004
Specific risks Bolts & Flanges
Bolts and flanges form crevices
Coatings are often weaker
Galvanic corrosion if dissimilar materials
(presentation 4)
WHERE DOES IT OCCUR?
-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
9/15Copyright Talisman Energy (UK) Limited 2004
WHERE DOES IT OCCUR?
Specific risks Uncleansurfaces
Build up of deposits on a surface
Salt deposits
Corrosion product
Fluid spills
Bird droppings
Residue/remains from tapes
-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
10/15Copyright Talisman Energy (UK) Limited 2004
WHEN DOES IT OCCUR?
When bare steel is exposed on asurface due to..
Coating degradation
Blisters
CrackingFlaking
De-bonding
Constant exposure to water
High traffic wear
Mechanical damage
-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
11/15Copyright Talisman Energy (UK) Limited 2004
WHEN DOES IT OCCUR?
When bare steel is exposed in a crevice by.. Ineffective seals on supports
Ineffective coating within the crevice
Poor design
-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
12/15Copyright Talisman Energy (UK) Limited 2004
WHY DOES IT OCCUR?
Why does the coating fail?Due to age
Due to poor application in field
Due to mechanical damage
-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
13/15Copyright Talisman Energy (UK) Limited 2004
WHY DOES IT OCCUR?
Why do deposits accumulate on surfaces?
Leaks/spills not cleaned up
Surfaces not kept free of debris
Corrosion product not removed
-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
14/15Copyright Talisman Energy (UK) Limited 2004
WHAT CAN BE DONE TO PREVENT IT?
Understand where and why the main
corrosion threats occur
Understand the systems in place toaddress these
Play your part Report any corrosion concernse.g. damage to coating, corrosion exposed when
carrying out routine tasks
Report any corrosion damage
e.g. Integrity Report cards, STOP cards, inform
Supervisor
Report any damage to coatings
Bolts ensure joints are assembled correctly
Clean up spills or debris
-
7/30/2019 Corrosion Awareness - Atmospheric Corrosion Rev1
15/15Copyright Talisman Energy (UK) Limited 2004
SUMMARY
Where does it occur?
Any areas exposed to water
When does it occur? When the surface is exposed
Why does it occur? Effective coating not maintained
What can be done to prevent it?
Effective fabric maintenance to preventextensive coating breakdown
Avoid leaks/spills onto surfaces from
above
Prevent accumulation of deposits/debris