Dear Sir,

I would like to know whether B16.5 permit to use Standard flanges with Metric Bolting instead of inches bolt, Vessel is constructed as per ASME SEC VIII DIV-1.

Can B16.5 flanges with Metric bolting be considered Standard or Non-Standard flanges?

If Vessel is code stamped "U", whether Metric bolts for B16.5 flanges are OK? Whether AI accept it?

Sunil Agrawal
Tecnimont ICB

Hi Sunil

That is an interesting question. I was employed by a South African inspection company, and we had this issue all the time. Metric bolts were the standard, and all the flanges were assembled with metric bolts. I allowed it without ever questioning it.

In the United States, the Authorised Inspector seems to have the last say. I cannot see any reason why he would have a problem with metric bolts, but first check with him.