U- Stamped Equipment - Machining of WNRF Flange to WNFF Flange 1

[Sajeev P]

Hi,

One of our projects, the contractor machined the WNRF Flange of U-Stamped Static Mixer to Flat face to match with the connecting piping. The equipment is new and the design code is ASME Sec-VIII Div. 1. Is it acceptable to convert the flange face of U- stamped equipment without following R-stamp procedure? Your expert reply/ suggestions are highly appreciated.

Thanks in advance,

Regards,
Sajeev

 

[SnTMan]

Sajeev P, assuming a B16.5 flange, that standard permits conversion from RF ot FF by machining off the raised face as long as tabulated thickness dimension "tf" is maintained. See 6.3.2.

Again, assuming B16.5, if this were done before hydro I'd see no need for an R stamp, afterwards I'd still say not, but it'd likely be up to the AI.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[LittleInch]

Even after hydro I can't see an issue with this. The RF bit is not part of the structural strength of the flange as SnTman explains, but agree that the decision isn't ours to make, but the AI. I would hope sense would prevail here.

You haven't changed or repaired anything and it remains a compliant ASME B 16.5 flange so long as he doesn't remove too much of the flange material....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[NBrink]

Have machined a ton of flanges on U-stamped equipment without ever even thinking about an R-stamp. Always assumed if you're still within B16.5, you're good to go.

NB Interpretation 98-30 seems to back me up on this

Addresses damage during operation, but I've machined damaged flanges all the way down to FF (as allowed by B16.5). I don't see how converting it wouldn't fall under the same interpretation:

Question 1: A pressure-retaining item has its surface ground or machined to remove imperfections caused during operation. Is the resulting reduction in outside diameter, length, and thickness caused by such grinding or machining considered an alteration as described in Appendix 6, Item C4?

Reply 1: No, unless the changes affect the pressure-containing capability of the pressure-retaining item.

Question 2: A pressure-retaining item has its surface ground or machined to remove imperfections caused during operation. The grinding and machining reduces the item’s thickness, length and outside diameter. Must such grinding or machining be performed by a holder of an "R" Certificate of Authorization?

Reply 2: No.

Nathan Brink