tanks in cold ambients 1

[timbones]

Consider an insulated oil storage tank operating in a cold ambient temperature. Does the tank material have to be suitable for operation at the cold ambient (in this case -40°C). The choice is to spec A-516-70N or just keep it cheap and go with A-36. Probably the only time the tank will get down to the cold temperature is when it's empty (at which point do I care if it has no impact strength). The rest of the time it will be near the temperature of the oil, which is at 60°C. Of course there is also the impact of filling a frozen tank with oil at 60°C.

Tim

 

[JStephen]

If heating and/or pumping gets shut down due to other problems, will the tank not cool off in a few days?

 

[JoeTank]

Unless the tank contents are heated, API-653 requires that the owner consider the tank as storage at ambient conditions. They use the low one-day mean ambient temperature plus 15F.

Joe Tank

 

[0707]

Tim

I suppose you need to have a material with impact strength at the minimum temperature the tank would be subjected.

luis

 

[timbones]

I think if the pumping were shut-off for a few days, the operators would be forced to drain the tanks to prevent the product from freezing. There is no situation that I can think of where the tanks would be allowed to drop to -40°C with product in them.

 

[0707]

timbones

you have put a question inducting the forum that tanks would be allowed to drop to -40°C. If this is a question of procedures operation that is another thing, which should be ruled in a different way.

 

[arto]

Go for the A-516, that way when something goes wrong, you won't have to explain something like:

http://twi.co.ir/download/case_studies/165 - Schenectady T2 tanker.pdf

;-)

Remember what John Ruskin used to say....

http://www.kirwood.com/jruskin.htm

 

[JoeTank]

timbones,
Is the tank inquestion in the US or Canada? If so, I think you have to follow API-650. You will have no choice but to select a material for a -40C location.

Joe Tank

 

[jrjones]

timbones,
I live in the frozen north of Alberta Canada, and all of our tanks are spec'd to have adequate impact toughness to -40°C. This obviously includes all the nozzles, attachements, etc. For the most part we use G40.21 44W plate. For the thick stuff (>1") we usually go with normalized material and we impact test as require by the thickness as per API 650.
Hope this supports you...
jrjones

 

[timbones]

jrjones,

This helps a great a deal. I too live in the wilds of Alberta and so will these tanks eventually.

It may seem obvious that for an Alberta location, notch tough steels to -40°C would be required but, this project I am working on is the 3rd phase of a plant. All 3 phases are engineered by different companies. Phase 1 tanks are made of A-36. Phase 2 tanks are A-526-70N.

G40.21 44W plate is something I had foolishly not considered yet. I don't normally deal with many tanks, so the CSA standard steels don't usually enter my mind that often.

Any idea what the order of magnitude cost difference bewteen the 44W notch tough normalised plate and A-516-70N is?

Tim

 

[deanc]

I strongly suggest you contact the Jurisdiction.

http://www.absa.ca/

May save you many problems. Dr.Lau is tops.

 

[jrjones]

timbones,
Not sure on the cost difference exactly, but I believe the 44W is cheaper..depends on the thickness you need.
jrjones

 

[AravindSujay]

A-36/44W is sufficient

 

[kenmac777]

Don't bother with ABSA - their jurisdiction is pressure vessels, not atmospheric storage tanks.

For what it's worth, one US Arctic mine I have worked with uses SA516-70 normalized plate for outdoor oil storage tanks.

An Arctic Canadian mine specified: "Material shall be in accordance with CSA G40.21-260WT, normalized and impact tested as per section 2.4.d. of API-650 or approved alternate"

Nozzles were spec'd "In accordance with ASTM A-333 Grade B. [Impact energy 18J at - 45 deg C]"