API 650 - Distance between T-joints and columns

[papuryan11]

I need your advices.

API 650 States that three-plate laps in tank bottoms shall be at least 300mm(12 in.) distant from each other, from tank shell, from butt-welded annular plate joints, and from joints between annular plates and the bottom.
But, it does not say anything about three-plate laps and columns inside a tank to support its roof. Seeing the said distance between T-joints and its shell, i quess columns shall be 300mm distant from T-joints.
are there any differeces between shell and columns?

 

[IFRs]

Columns do not matter in this regard.

 

[JoeTank]

API650 does not specify a spacing requirement for three=plate laps vs. roof column base assemblies. While is is considered good practice to avoid placing a column over a three plate lap joint, there are probably thousands of tanks with this condition with no general problems observed.

Joe Tank