Corrosion risk planning - 2 - Above ground storage tanks - oil and gas- PART 1

Above ground storage tanks

1. Inner walls

Coating degradation
Corrosion due to water/dissolved oxygen
insufficient/damaged cathodic protection system
dissolved sacrificial anodes

2. Outer walls/roof

Atmospheric corrosion
coating degradation due to moisture + UV radiation + temperature
Erosion and wear due to wind and dust particles
biological growth at the bottom areas near soil
soil corrosion near the bottom

3. Pipes

Atmospheric corrosion
Coating degradation
mechanical failure
internal corrosion due to water/dissolved oxygen
crevice corrosion in areas facing away from atmosphere
corrosion at welds and joints
microbial corrosion at 6 o' clock positions
erosion corrosion at bends

4. Railing

Coating degradation
Wrong coating selection based on pure aesthetics
coating damage at joints and bends
corrosion at welds in the railing
crevice corrosion at fixtures
pitting corrosion

5. Breather valve

uniform corrosion/pitting depending on whether it is made up of carbon steel/stainless steel
Galvanic couple at the joining/welding point of valve to roof
corrosion after damage of galvanized layer

6. Spray nozzle

Crevice corrosion at orifices
clogging
erosion and mechanical damage at orifices and bends
crevice corrosion at fixtures

7. Manhole

corrosion at edges of cover
galvanic corrosion at contact points with neighbouring parts
pitting due to chloride ion contact
crevice corrosion at fixtures
pitting corrosion at welds

8. Lagging

pitting due to chloride ion contact
crevice corrosion at overlapping joints
water seepage at insufficiently bonded overlaps

Click here for part 2!

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