UW-9 (d) of ASME Section.VIII Div.1

[Vattappilly]

Thanks metengr for the reply to my last question about blue brittle range

I do have a question about UW-9 (d) of ASME Section.VIII div.1

We typically separate the longitudinal seams on a shell with 2 courses by 90 degrees. As per the above paragraph we do not need to do that when we radiograph the seams at least 4" each side of the circumferential weld intersection, right?

Can anyone think off any technical reason why we have to separate the seams in the event of not doing radiography.

Is it because when you have a continuous seam, may be a defect like crack or something could propagate right through the entire length of the seam?

 

[tmdixon]

To put it in very simple terms; for the same reason that bricklayers stagger bricks and dont just stack them one on top of the other.