Nozzle Opening on Knuckle Area (Head)

Hello, I assume you are installing the nozzle on an ASME pressure vessel . On a new ASME vessel you can install most any nozzle anywhere you desire as long as the calculations are done to check that all the parameters such as proper wall thickness, size, re-enforcement requirement etc. are checked and approved by your AI, the ASME code and your own company QC manual. Also you must have the proper fabrication stamps (probably a U stamp in this case) required for this type of vessel fabrication.

If you have the original drawings and documents for the existing vessel then you may just need to check that they are compliant with the current ASME NBIC code edition/addenda. If they are still in compliance you could revise the documents with information for the new vessel and use these documents instead of starting over with everything for the new vessel as long as your AI agrees to it.

If you were Installing a new nozzle per ASME NBIC code in a different area on the head of an existing vessel it would usually be treated as an alteration. Doing an alteration on a ASME vessel will require you to do calculations similar to calculations required on a new vessel to check if the wall thicknesses of the shell and nozzle is adequate and also if you will need a re-enforcement plate around the nozzle

On the other hand if you are just replacing the old nozzle exactly like it is on the original drawing and the same location it should be treated as a repair and it could possibly be treated as a repair of a routine nature if it is below 5" NPS and your AI allows it. Either way a repair does not usually require having new calculations done because it this was covered in the original design and you are not changing anything.

Good luck with your vessel,

Pipewelder,

You said: "On the other hand if you are just replacing the old nozzle exactly like it is on the original drawing and the same location it should be treated as a repair and it could possibly be treated as a repair of a routine nature if it is below 5" NPS"

The 5" maximum size for routine repairs is for pipe & tubes...Not pressure vessel nozzles... Check the NBIC interpretations...

OLD A/I.....