API 650-Bottom shape selection
API 650-Bottom shape selection
(OP)
Dear all,
I have seen storage tanks (crude oil, diesel, kerosene,..) which have different bottom types: some of them have conical shape (slope approx. 1:120) with the tank center being the highest point and a drawoff sump near the shell but in other cases the bottom has inverted conical shape with the tank center being the lowest and a drawoff sump in that center.
Does anybody knows the advantages/disadvantages of each solution?
Best regards and thank you
I have seen storage tanks (crude oil, diesel, kerosene,..) which have different bottom types: some of them have conical shape (slope approx. 1:120) with the tank center being the highest point and a drawoff sump near the shell but in other cases the bottom has inverted conical shape with the tank center being the lowest and a drawoff sump in that center.
Does anybody knows the advantages/disadvantages of each solution?
Best regards and thank you





RE: API 650-Bottom shape selection
Edge sumps require less piping, and don't have to dodge the center column. Center sumps should help avoid corrosion around the shell, and drain to a single point better.
RE: API 650-Bottom shape selection
RE: API 650-Bottom shape selection
This particular issue is discussed in detail in Phillip Myers fine book "Aboveground Storage Tanks" (McGraw-Hill)
You will find different opinions by different "tank experts" on this issue. The best choice depends a lot on the liquid stored, the tank coating system and the expected design life of the tank.
In my understanding, for storage of crude, cone-up or flat bottom is preferred because corrosion is not concentrated in the center of the bottom. Corrosion there is harder to detect and repair. A downside is multiple water draw-off points on the tank perimeter
For storage of less aggressive liquids,...your choice
-MJC