SO flange facing welding
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For the technical improvement project, the design documents specified WN flanges; however, once they were used up on site, a PL flange was found and was welded in place directly. During the pressure test, there was a leak; it turned out there was a gap on the flange. Let’s try another one.
This is what they call making do! You’ll be stunned when something goes wrong
During the second welding, I was on site and didn’t pay attention to whether it was a WN or PL flange. I saw that they didn’t move the valve underground before starting to weld it. After welding, they asked me how it turned out, and I nodded.
PL flanges can’t be used just as one wishes; it depends on the pressure level specified in your design
During the first welding session, there was a very small crack on the body of the PL flange; I took pictures of it, but the images weren’t clear. Perhaps the welder didn’t notice it, or some people say that they are paid based on the amount of work done, and they didn’t report it since they saw no weld defect. During the pressure test, we found that there was a leak.
The pressure is not high; it’s 4 kg, with a PH of 10. I checked, and using WN as per the original design represents an overkill – using PL is sufficient. The problem lies with the PL welding: during flat welding, both the inner and outer sides of the flange need to be welded. However, the butterfly valve located beneath the flange was not removed, and it’s clear that the inner side of the flange wasn’t welded at all – only the outer side was welded. Doesn’t this essentially turn a flange that is to be welded flat into a flange that is to be welded butt?
SO refers to socket welding, while BW refers to butt welding. Who told you that SO involves butt welding?
SO refers to socket welding, while BW refers to butt welding; please do not mislead people. . . . . .
Common flanges: SO is flat welding with a neck, WN is butt welding, SW is socket welding, PL is plate-type flat welding