I required to use 10" #150 Sch10 WNRF in U stamp vessel. My supplier has 10" #150 Sch40 WNRF and he had machined the ID to Sch10 and supplied to us. My query is
1) My supplier or as a U stamp manufacturer(we) are allowed to machine the ID?
2)If yes, is it required to modify marking on Flange & certificate.

Yes. Issue a NCR whose resolution is: Machine to size and correct stamping and MTR.
mauro

Mr Gonzaga

The flange at first place was supplied or procured in machined condition to meet the job requirement. There is a marking on the certificate modified to suit the required size. Received material meets the requisitin and job requirement with note on the mtr or with an addition certificate of compliance. Then what will be the basis for issuing the NCR.

Secondly not being the manufacturer of the Flange how can I change the marking and material test report.

Regards
Prashant

I do not understand the problem. Is the MTR corrected by those who machined the flange and marking remained with old entries? If yes then you have a NC because of the discrepancy between marking and MTR.
Mauro

Mr Gonzaga,

Please find the following interpretation from B16.5
Interpretation 2-24
Subject: Welding Neck Flange Bores and Remachining
Date issued: May 28, 1991
File:B16-90-32
Question (3): Does B16.5-1988 prohibit the machining of a welding neck flange which was originally manufactured with a smaller bore to produce a flange with a larger bore?
Reply (3):No
Question (4): According to B16.5-1988, when a flange is remachined by an organisation other than the original manufacturer, is it neccessary for the original markings to be rteplaced with new markings?
Reply (4): B16.5 does not address remachining or replacement marking of flanges

Hence how it will be a Non Conformance?

So, if you are happy, why are you arguing?
Apart from the interpretation I would argue about a flange marked with the wrong sch.
But I am considering another possibility: why not machine the welding preparation only? Just to fit the pipe of lower sch. Pipe spec. only requires min. tolerance of 12% on pipe thk. and no tolerance for excess thk.
Mauro