Preheat temperature of A335-P5 1

[DBreyer]

Hello all,

in our company's internal standard until now a preheat temperature of 300°C for welding P5 piping is required.
Now a disucssion is started weather a temperature range of 250-300°C is also acceptable.
In every case PWHT is required so I don't worry over much about remaining martensite.
Also Asme B31.3 requires an even lower preheat temperature.

Does anybody know of a standard (api, nace,..) requiring at least 300°C preheat temperature?
Pipes are used in corrosive (mainly sulfidation) refinery service.

Thank you for your advice.

Daniel Breyer
Inspection Engineer

http://lnkd.in/dFcQA-w

 

[metengr]

For SA 335 P5 alloy steel, a proper minimum preheat temperature is 200-220 deg C. Having a preheat of 300 deg C is of little benefit and places you up against the interpass temperature limit. What was the basis for my recommendation? - ASME B31.1 for P-No 5B materials, which is conservative.