ASME PCC-2 6in welding distance requirement

[abehong]

As per the 3.8 Article 2.1 in ASME PCC-2, it requires to maintain a minimum distance of 6 in between the nozzle attachment weld and the nearest edge of the insert plate butt weld. I am wondering what is basis to select the 6” spacing, not 8 in or 4 in. It seems not to include this requirement in ASME VIII Div 1 code.

Thanks
Abraham

 

[DanTh3Man]

I've got a question along these same lines. I had a weld on a nozzle fail and am looking to repair it according to article 2.1 however there is another nozzle 6" away from the first. I am worried that installing a patch so close to the other nozzle weld will lead to another failure.

A little more info: the nozzle being patched is a 1-1/2" pipe and the other close nozzle is a 6" pipe. The vessel was originally built to the 1977 edition of ASME Code for Unfired Pressure Vessels Division I.

Perhaps someone could recommend another repair method?

 

[metengr]

When you say nozzle failure this is not descriptive enough. Why not perform local weld repair versus replacement of the entire nozzle? Why not replace the nozzle if it failed?

 

[DanTh3Man]

I got it all sorted out, I had missed the part about the patch for nozzles under a certain size not needing to be any larger than twice the diameter of the nozzle.

We had the weld between the nozzle and the shell crack. The crack really turned into a hole as it was more than 1/4" wide in some parts. A weld repair was made but our policy classified it as a temporary repair so now I have to go back and get it fixed. I have questioned why the existing repair cannot be permanent but I suppose those decisions are made above my pay grade.

 

[chicopee]

What I would like to know is the cause of the weld failure; is it perhaps an undue external loading?

 

[racookpe1978]

Draw that geometry please: That some one "above my pay grade" made a (bad) decision does not mean you are right in following it.

However, having said that, I do not see any reason why a "patch" would be - or even could be! - safer or more correct.

 

[Ripz]

racookpe1978

Repairs, in this case, the patch, made according to ASME PCC-2 are considered safe solutions and the majority are considered permanent repairs.

...

The patch in this case, is a solution if the problem was wall loss. Not a crack, as it turned out not to be. Grinding out the defect and rewelding is an acceptable repair. I also don't understand why Danth3man's company doesn't consider it permanent.