API 650 Bottom

[djgiles07]

First, I'm new to API 650 and the forums, so I apologize if this has been addressed in the past. A customer has requested a shop welded, stainless, API 650 tank with a 20-degree slope conical bottom. When we've built this tank in the past, it has been built on a frame, i.e., without the bottom being uniformly supported. I've seen some conflicting information as to whether or not API 650 covers conical bottom tanks. Is there an acceptable tank support structure, or does the tank need to be sitting on the ground?

 

[fegenbush]

Per paragraph 1.1.1 of API 650, the bottom must be uniformly supported. There are many ways to accomplish this including, but not limited to, ground support.

 

[fabtank]

djgiles07,

For API 650 the bottom must be uniformly supported as fegenbush has pointed out.
This type of tank could be designed to API 620 or even ASME SEC VIII Div 1.

 

[MJCronin]

Dj....

This can be accoplished by installing a sloped bottom "up inside" the shell of the tank.

From the outside, you cannot tell that the tank bottom is sloped...

The void beneath the tank bottom is then filled with grout. Vent holes through the bottom of the tank skirt have to be located to ensure that the bottom is supported.