I am welding a 2" 300# Studding outlet (Normalized) on an existing vessel. The vessel shell material is SA 516-70 Normalized, 1.25" thick, but not PWHT as it is not in severe service. The Studding outlet wall is 2.25" thick and it is "Set on" with a 7/8" fillet weld on the inside and 1/2" fillet weld on the outside.

PVElite says that due to the geometry, the nozzle must be PWHT, I specified that the vessel shell was not PWHT. The client does not want to do PWHT on at 144" Dia. vessel. My explanation was that PWHT was specified solely on the Studding wall thickness and not weld size. I proposed Method 1. Higher preheat temperature as an Alternate to PWHT per NBIC R-1000. He still questions why PWHT was even specified since we are also welding other nozzles "set-in" with full 1.25" groove welds.

Can anyone shed any light on this PWHT requirement based on geometry?

Hello Mr Carter

We are going to have to look into this, as you appear to be correct, in that PWHT is not required for that configuration. I have added your concern to the list of future features to be considered.