Painting the underside of fixed roof tank.

[jfreddy]

Hello guys,

Is it required by API to paint the underside of fixed roof tank? The contents in the tank is Heavy fuel oil (Bunker C).

 

[LittleInch]

Do you mean API 650? API as an institution wouldn't care.

API 650 doesn't state it one way or the other, even for the outside, but it wouldn't look very nice after the first rain storm. API 650 refers to painting as a coating.

7.1.4 just says "Coating or other protection for structural work inside and outside of the tank shall be as specified in the
contract and shall be applied by competent workers."

SO if you don't specify it it won't be done.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[TugboatEng]

Bunker C? You can't even buy that stuff anymore.

Is the tank going to be heated? If yes, there will be less chance for condensation inside and a ceiling coating becomes less important.

 

[rb1957]

how much oil are we talking about ? a 44 gallon drum, or a Florida waste pond ??

another day in paradise, or is paradise one day closer ?

 

[jfreddy]

The capacity of the tank is 400,000 UK gallons and the tank is not heated.

 

[LittleInch]

The contents, size and temperature are irrelevant to the question.

Is it required by API 650? - No

Was it written into the spec or data sheet? Don't know, You tell us.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[jfreddy]

LittleInch, I understand that protective coating is not required by API but it is recommended for obvious reasons. My question now, is it recommended to coat the underside of a fixed roof tank holding 400,000 gallons of HFO? Will vapor be a major concern?

 

[JStephen]

Practices vary, depending on the product, the owner, the usage. Some tanks will be completely unlined. Some will have the lower area lined where water might collect. Some will be fully lined- in some cases, for product cleanliness. Lining may affect length of time between inspections- see API-653.

 

[LittleInch]

I'm finding it difficult to believe an HFO tank of any sort is not heated. This stuff goes like treacle in even ambient temperatures.

Is it recommended? I would say yes it is on the basis that when you're building it it should be fairly easy to do and in the event you get condensation or water in there, the roof is where it is most likely to condense and slowly drip or film and hence corrode. Vapour off HFO is non corrosive and would probably result in a film of sticky oil which would protect the steel surface.

But then thousands of fuel tanks are built and operated without being painted or coated on the roof or exposed walls so it's pretty much a "nice to have". IMHO.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[jfreddy]

A suction heater is being used for pumping the fuel out.

 

[TugboatEng]

Coatings are nice when you have to service the tank, it makes them easier to wash. Coatings at the bottom of the tank are important if the fuel has a high sulfur content due to microbial corrosion. This is true if your fuel is in fact Bunker C. Most of us have to burn ultra low sulfur fuels now which does actually minimize the corrosion problem. IFO 380 has superceded bunker C in the marine industry, it's not so good in boilers.