Partial Bevel Weld on Nozzle

[OnG_Engr]

All,

Today I had a situation where I was over-ridden regarding the use of a full-pen weld on a high pressure (6000 psig) nozzle versus a partial-penetration bevel weld with a small fillet weld on the opposing side. The computer program said a partial-pen weld was okay, so management decided to go with a partial penetration weld. One reason I've always used full-pen welds on high pressure applications in the past was out of concern for corrosion getting behind weld. However, the counter argument would be that it's sealed off with a fillet. I still don't like going with anything less than full-pen because of potential unknowns (fatigue?). Given it's over 3000 psig, I think you'd want to over-design anyway due to U-1(d).

Since my industry experience isn't a sufficient answer, does anyone have a more documented reason not to do it?

 

I am not a designer so I cannot answer your technical question, but my gut feeling agrees with you that at 6,000 psi the prudent approach is full penetration.

However I do detect an issue with your management, who will challenge an engineer who presents valid reasons, but not challenge a computer program whose output comes out of a black box.



"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[SnTMan]

You got that right...

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

 

[r6155]

Example: NPS 2 nozzle in 300mm thick shell that can be fillet welded inside and outside the shell. I saw something similar for Reactor Pressure Vessel (Nuclear).

Regards

 

[JStephen]

I've seen it both ways. I would not expect the corrosion in the sealed area to be a problem, though.

 

[OnG_Engr]

After digging through UW-16.1, it look's legal; however, I think they're going to have trouble with U-1(d) since a full-pen would have been an easy "addition"(ABSA lists full-pen as meeting the U-1(d) requirement).

I wonder if there is a weld requirement in 49 CFR 192?