Poor Fit-up and Welding

Date 09-26-2013 17:03

We delivered an SS304 round section to a client for their own fit-up and welding to their existing vessel sections.
Diameter about 2 metre and wall thickness 10 mm.

Before welding, I was at their site to inspect the fit-up, with the sections tack welded together.

The numerous issues encountered included the following.
1. Diameter of client's section is bigger by about 10 mm.
2. Butt joint not level at most points round the circumferential grooves. Misaligned by half wall thickness or more.
3. Gap distance varies between 2mm to 5mm.
4. Suppose to be single V groove joints but at many places can see transition from single to double V grooves.
5. Bevel angle not uniform and varies greatly.

The welding process is SMAW.
I have not seen such poor fit-up before and when asking client's contractor about the gaps, the reply was "no problem can build up".

My question is: if the joints are welded and passed RT, is there any concern with weld integrity and good for long term service?
Vessel is operating under full vacuum condition.

Boon

By welderbrent (*****)

Date 09-26-2013 19:32

Loaded question Boon.

It is really going to depend upon the end use strength required, any codes involved, any jurisdictional involvement from a gov't agency, type of support, etc.

Under many circumstances it will work. It just depends upon what they want and/or need.

There are many ways they could compensate for the diameter difference, including leaving it and making sure there is a good transition so thickness is not an issue.

The gap can be ground out for more clearance in the tight spots. 5mm should not be too wide.

Safety is always more of a concern than some of the other factors. But with the right welder on the job it would probably be fine.

So, any codes or jurisdictional issues?

Have a Great Day, Brent

By Boon

Date 09-26-2013 23:18

I recalled code is according to certain section in ASME.

"Good transition" is going to be the weld itself, not another section piece.

Boon