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[MW:2650] Welding after PWHT

By Materials & Welding
Friends,
 
While fabricating pipe spools as per ASME B31.3, A pipe welded with an Orifice flange was undergone PWHT in the furnace ( the branch nozzle on the orifice flange was not welded before PWHT ) and the contractor wants to weld the branch nozzle on the Orifice flange after PWHT & doesn't want to carryout local PWHT.
Is it acceptable???????  or the preheat & inter pass temperature shall be minimum 150 Deg Celsius.
Regards,

Tulasi Ramu

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