Code Repair Requirements

[meister]

I have several new coded vessels. The outlet nozzle is actually quite long (6 feet) due to fit up requirements. I need to weld on this "pipe" prior to the first flange/nozzle. Is this pipe considered to be part of the vessel falling under code repair requirements, or can it be treated as pipe B31? There are several existing circumferential welds closer to the actual vessel where my weld will be. I need this weld to correct fit up problems. Please reference code paragraphs when responding. THANKS

 

[jte]

meister-

Oh, what a can o' worms this one will be! This issue comes up frequently with outlet nozzles which extend from the bottom head through the skirt. You may have a vertical length of pipe welded to an elbow (arguably the "first circumferential seam&quot welded to a horizontal length of pipe welded to a flange. This can lead to confusion in interpreting VIII-1 U-1(e)(1).

At my location we (the engineers) have come up with a position that if it was supplied by the vessel fabricator, it is a part of the vessel. Code forms these days are much more complete than they were years ago. If the nozzle is listed on the U1 or U2 form and includes info on the pipe and flange, you'd have a hard time getting our local AI's to believe that it's B31 piping.

You say that these vessels are new. In this case, you should have calc's for them provided by the fabricator. Did the fabricator perform any B31 calc's or did they only do VIII-1 calcs? If they did B31 calc's, then you stand a chance of convincing the AI that its just a chunk of pipe which happened to be supplied by a vessel fabricator!

jt

 

[meister]

The flange and pipe are part of the vessel. We should have specified up front when we purchased that the vessel ends at the first weld but did not do this. We will modify the pipe that connects. Thanks for your help!

 

[chili]

Our practice has always been that the vessel includes everything up to the first flange or fitting....which agrees exactly with what JTE is saying. Another way you can look at this is "how can you do a hydro test with an open hole?" Obviously you can't, so either a plug must be screwed in or as in your case, a blind flange will have to be used. This act identifies the pressure boundary.

I hope that helped.

Chili

 

[engatwork]

I agree with the other post - I would consider it a part of the "pressure vessel" that falls under the pressure vessel codes.