weld overlay for flange (standard B16.5 or non-standard)

[ksquare]

Hello, can anybody please tell me if the B16.5 welding neck flange permit to be weld overlay? i don't find it documented in the code (maybe overlook by me). And, How about those custom flanges designed base on App II in ASME sect VIII div1 or App III in Div II.
Thanks for any answers.

 

[SnTMan]

ksquare, Apx 2 flanges first. No problem weld overlaying them, weld overlay and any facing is additive to the calculated thickness. PWHT as required by the base metal.

B16.5 flanges are not so clear cut, but a common practice is to machine a counterbore in the facing area, typically 3/8" deep and fill with overlay, then remachine the raised face to original dimensions. I am not aware of any standard or code that specifically permits this but it is done all the time.

Regards,

Mike

 

[unclesyd]

I will admit no guilt to 50 years of weld repair to flanges of all descriptions. We try to do the weld repair and remachine in place for the larger flanges. We have in house face facing tools to 60". Welding tools to 48".

We have several hundred pipe spools with Class 2500 A105 Flanges that have undergone several weld repairs and remachining. The main area of interest is the spotface on back of the flange, nut landing area. It is the usual practice to to rework the gasket seating area, raised face, at the same time. We have at times weld repaired the bore and remachined to the proper diameter.

We try not to take any material from the flange proper that would affect it's strength.