Socket weld bevel

[brendan10]

We are currently in fabricating a project that consists of about 5000 socket welds. Recently the client have X-rayed abot 60 welds to check the gap. The results for the gap were 100% clear. However they found a "lack of penetration" right in the corner of the weld on about 30 welds.
On further examnation it was noted that over 50% of the fittings have an inside bevel of about 2mm top and bottom.It looks like the bevel is tohelp putting the pipe into the fitting. Can someone please advise if this bevel could be the cause of the lack of penetration.

 

[stanweld]

The ID bevel on the socket fitting could be a cause of the bridged root (lack of root penetration) or the illusion of same when viewed under RT. Was the ID bevel 2 mm deep into coupling or 2mm added radius around the circumference or both? Have you checked a cross section through one of the sockets?

 

[brendan10]

The ID bevel is on both surfaces and we have a cross section. You can see a 0.5mm hole right at the corner where the pipe meets the fitting. Inside this hole what you have is the void / gap between the pipe and fitting.

 

[Ballbearing1]

Brendan10,
That will be a perfect spot for slag to get trapped if your welders are not welding hot enough.
Give the edge a quick grind to remove the bevel and bring it to a square edge and turn the amps up a bit and see what the RT is like on that.
We have had welds in the past that have been RTed to ensure appropriate gap and they have failed due to LOP on the fillet due to the welder welding too cold.
Hope that helps,
BB

 

[vesselfab]

That's why we use GTAW for all socket welds in our shop.

good control for penetration and no trapped slag and no pin holes.