We are having a Contractor install new nozzles into exiting columns and vessel at Shell .
We are under the impression in order to stress relieve the nozzle attachment, a circumferential band would have to be heated all around the vessel. This is according to ASME Section VIII, Div. 1, Paragraph UW-40(5).

The Contractor though is telling us instead of heating a band they can heat a 'donut' around the nozzle. According to them there are ASME Code cases where this has been allowed. Of course they can't show us or tell us which Code case(s) they are. It is also quite difficult to find a specific ASME Code case.

I know API 510 allows a 'donut' instead of a circumferenital band but this repair/alteration is being completed to the Code of Construction, ASME Section VIII, Div. 1.

Should we do PWHT between entire band or donut ?
Thank you so much .

I believe you mean UW-40(a)(5)..... Please read UW-40(a)(7) and if that does not apply, then read UW-40(a)8 which discusses all other configurations not listed in (a)(1) thru (a)(7) and may be the "catch all" for situations such as yours.

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You have to PWHT the entire girth band of the column in way of the nozzle. Mauro

Same discussion two years ago with many opinions here is the link......
http://www.eng-tips.com/viewthread.cfm?qid=97307&page=68

_________________
A question properly stated is a question half solved.