distance between two longitudinal seams if they are in the same shell

[taba94]

The distance between two longitudinal seams in the adjacent shells shall not be less than 5t where t is the thickness of the thicker joint as per API-650, I wanna know what should be the distance between two longitudinal seams if they are in the same shell? off course it depends upon the available sizes of the plates but how much at least it should be ?
ASME or API does not give any referrence regarding this issue.

 

[SnTMan]

taba94, I'd go 5t min, for the same reasons. Even that would be nasty. Otherwise, they should be spaced such that they miss any nozzles or other attachments. I am not aware of any other guidance on the issue.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[JStephen]

Is this an API tank or an ASME vessel?
Generally, the issue with the API tank would be weld distortion, with several feet preferred. Basically, you're asking, how short can a shell plate be.

 

[taba94]

i havnt found any code source for this issue.
but from my view point it would be desirable to separate two weld joints ass long as prevent their HAZs to overlap each other.

 

[SnTMan]

I'd kind of take that as a minimum

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[BJI]

Similar to the distortion mentioned by JStephen, weld peaking and flat spots or out-of-roundness would be another concern when constructing with such short pieces. Have a look at the tolerance limits in the code, otherwise you might see fatigue cracking after relatively short operating periods.

 

[taba94]

so this means we have to consider it from u-1(g) BPVC and our engineering judgement.

 

[BJI]

Since you mentioned API 650 I am assuming it is a tank, so you should follow the tank code not the vessel code. I think you mean U-2(g) but this is the vessel code, so what is it? Maybe you should start by clarifying this question asked twice now before going further.

 

[r6155]

Min. distance : 5 t
Prior to rolling no undercuts, PT or MT and RT spot.
After rolling and prior to weld the second seam: RT 100%.
PWHT must be considered.

This is good engineering practice for pressure vessels

Regards
r6155