Pre-heat temps for B31.3

[RUD8]

What is the applicable code and requirements for pipe temperatures prior to welding for B31.3 and B31.1?

 

[metengr]

ASME B31.1 and B31.3 are Power Piping Codes issued by ASME. These piping codes provide the necessary guidance for weld preheat and post weld heat treatment requirements based on the pipe material you are joining.

 

[DSB123]

metengr,
Just a correction to your post. ASME B31.1 is the Power Piping Code and ASME B31.3 is the Process Piping Code.ASME B31.3 is not Power Piping.

 

[TBP]

I believe the preheat requirement should be spelled out under the WPS registered under Section IX, shouldn't it?

 

[metengr]

TBP;
The WPS may have only a minimum preheat temperature used to qualify the procedure. The preheat actually specified could be higher, and this is permissible (elevating preheat) by Section IX without having to re-qualify the WPS.

 

[1969grad]

250 F seems to be the temperature used in most welding specs for high strength CS. To my knowledge the pre-heat temperature is not listed in the B31 codes but is part of the qualified welding procedure.

I have always understood that this temperature was determined based on experimental tests long ago rather than any type of analytical method.

Pre-heat is not normally required for Grade B pipe and fittings.

 

[metengr]

1969grad;
Preheat requirements are provided in B31.3 (see Table 330.1.1), and see 131.4 Preheat Temperature section in B31.1.