ASTM Vs SAE Fasteners

[TBP]

I've tried asking this on the ASME (mechanical) part of this site a couple of weeks ago. Nothing so far, so I'll try it here.

Is substitution allowed for B7 bolts/studs & 2H nuts with the much more readily available SAE Gr 5 and/or Gr 8 fasteners for pipe flanges under codes like the ASME B31.1 Power Piping Code?

All of the codes and reference material I can find ONLY refer to ASTM A-193 bolts/studs and ASTM A-194 nuts. I can find no "equivalents" for these, yet I continually see SAE Gr 5 & Gr 8 (usually Gr 5 because they're cheaper) used for flange bolts on piping in a lot of general industry plants (all of the steam systems I'm referring to are below 300 PSIG, most are 250# or less, and the compressed air systems are typically 125#).

I don't think that the substitution of ASTM fasteners with SAE is proper, but I've been wrong before. And I cannot honestly say that I'm aware of any catastrophic flange failures due to SAE fasteners being used in these pressure/temperature ranges. The inspection authority is unable or unwilling to give anything like a clear answer.

Does anyone have an opinion on this? Can you point me to some specific documentation?

 

[ghillis]

An air system is not power piping, yes it may have a lot of potential for release of energy, but it is not covered. I believe that small piping is exempt from the requirements of B31.1.

 

[TBP]

In Ontario, compressed air systems where the safety valves lift over 15 PSIG, fall under ASME B31.1 if they are over 3/4" (any pipe size if they are welded or brazed).