bitumen storage tank with non frangible roof joint

[geliberman]

In bitumen storage tank seismic design (for SUG III) we have to consider a large freeboard.
this area will increase the explosion risk of the tank.
how can we fulfill the api code without increasing the freeboard.

 

[fegenbush]

You could design the roof and shell to contain the sloshing liquid per Note c in Table E.7 (API 650 12th Edition) and add emergency venting in the form of an emergency manway cover or similar device that will provide adequate venting per API 2000.

 

[geliberman]

Dear Fegenbush,
in E7 table:
1-secondary containment is provided to control the product spill.
2-the roof and shell are designed to contain the sloshing liquid.
could you please send a photo or sketch for containment stated in item 1
what is the exact meaning of the roof and shell are designed to contain the sloshing liquid.

 

[MJCronin]

Just a thought...

Sloshing in a bitumen storage tank only occurs when there is a very slow earthquake........ correct ?

MJCronin
Sr. Process Engineer

 

[JStephen]

geliberman, refer to this paper for one:

http://nebula.wsimg.com/60561cce2d8...ccessKeyId=D06FA9C7F17A7303806A&disposition=0

MJCronin, I assume you're meaning a more viscous product would slosh slower, but if it's heated, it's not necessarily thick like you might imagine. The viscosity, or lack thereof, doesn't enter into normal sloshing calculations.

 

[IFRs]

Excellent article, JStephen - thanks!

Secondary containment can take the form of an impervious dike ( earthen, concrete, etc ) around the tank, or a slightly larger steel tank outside the tank in question, in either case an impervious floor of the space between the tank and the dike, etc. Think - the tank leaked all of it's liquid out and we don't want that liquid to get into the aquifer or be a risk to anything else, so the spilled liquid must be contained from leaving the immediate area.