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[billybedeveril]

I have a system where the predicted metal temperatures of carbon steel flare piping are lower than the MMDT of -29°C.  I'm trying to figure out the allowances given in ASME B31.3 Chapter III to see if I can reduce the allowable minimum temperature.

 

The material is type 3 in Table 323.2.2 (carbon steel), therefore it seems that the material must be heat treated as per A333 then impact tested, however:

ASME B31.3 then goes on to say in Section 323.2.2 paragraph d that impact testing is not required provided that the stress ratio as defined in fig. 323.2.2B is <1.  OK, I get that, in this case stress ratio is <1, as the MAWP is far higher than the operating pressure at the minimum temperature predicted. 

 

Question is, does the material still have to be heat treated, even though impact testing is not required?  The code doesn't specifically say whether this is the case. 

 

ASME is a bit confusing around this point.  Any help much appreciated!

 

Thanks! 

 

Jim