Bottom weld

[JoseAcevedo]

Does anyone could tell me. Why is it recommeded, for API 650 Vertical tank, to make a buttweld joint for the bottom's plates with thickness of 3/8" and thicker?

Is There any trouble in having lap weld bottom joints?. Why?

 

[JoeTank]

3/8 is about the limit of a fabricator's ability to field form the breakdowns and three plate laps for a lap welded bottom. They have learned the hard way that it is very difficult to build a fully lap welded tank bottom at thicker than 5/16. That's why you normally see a butt welded bottom when the thickness exceeds 3/8"

Joe Tank

 

[JoseAcevedo]

Well Joe.

Could you clarify if is it possible or not to build a 3/8" plates lapweld bottom.

 

[archimedez]

It is most certainly possible to build a 3/8" lap welded bottom. I have seen it done more than once. But as Joe said it is difficult and presents several challenges for the fabricator. It might also turn out to be more economical in the long run to build a butt welded bottom. Is there some reason you want to use a lap weld rather than a butt weld?

 

[BJaffa]

Our experience is that the difficulties with the "breakdowns" on 3/8" floors is minor compared to greatly reduced time for lap fitup and welding. I would think 3/8" is the practical limit.