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PWHT for -43degC in A333 GR6 pipe

PWHT for -43degC in A333 GR6 pipe

PWHT for -43degC in A333 GR6 pipe

(OP)
Do you need to PWHT fillet welds in A333 gr6 pipe
for propane duty down to -43degC (-45degF)?

As material has P No.1 pipe does not need PWHT unless thicker than 19mm (3/4") according to B31.3, but I think this might be a bit simplistic due to the low temperature?

RE: PWHT for -43degC in A333 GR6 pipe

a333 Employed frequently with Fillet Welds and Socket Weld Fittings at temps Lower than this....Contents would be Ammonia and Carbon Dioxide, and the CO2 would be at a considerably higher pressure than Propane in most cases.

Weld Engineers will tell you there is not such thing as a well designed fillet weld, and PWHT will resolve some of the circumferential residual stresses...Course the reason for using 333 is not the non-dynamic, standing pressure concern but transient pipe conditions, mainly associated with phase change or rapid acceleration of the contents.  

PWHT is going to recover some of the original fracture toughness in a localized sense, but the comparison between Charpy testing and pipe rupture or joint degradation mechanisms is not quite a closed loop.  These mechanisms have been well studied by the refrigeration, cryogenic and oil pipeline folks, and they reccommend against PWHT for field pipe welds.

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