For applications where you have no Codes or Standards for guidance, the typical preheat for this material is about 200 deg C (about 393 deg F). I like to go with a slightly elevated preheat, and PWHT is 705 deg C to 732 deg C. I would go with a PWHT time of 1 hour per inch of weld deposit thickness.
I have been told my interpass is 150 centigrade for the first two runs then 300 after , with the maxium interpass temp being 400 centigrade. Striaght after welding has the PWHT have to be done .The company we use is 35 minutes away willi have to maintain the temperature or do I have to wrap it and let it cool graduially before PWHT.
Whose requirements are referring to? Not B31.3's, but is your customer dictating?
If it is acceptable per the Code of reference and or to your customer, you can slow cool the weldment prior to applying PWHT. Some specs though, require preheat maintenance, and or it may be part of your WPS?
I have just got the drawing for the job the procedures I need to run are for 21/4% Cr 1 Mo to A106 C/S , 2 1/4% Cr 1 Mo to 1 1/4% CR 1/2 Mo , 1 1/4% Cr 1/2 Mo to A106 C/S.
If a run a Procedure for 2 1/4% Mo 1 butt will this cover me for the 2 1/4% Cr 1 Mo to A106 C/S.
Yes it will, per ASME Section IX welding guidelines. If you qualify a weld coupon that is P-No5A to P-No5A material, the corresponding WPS can be used for P-No5A to itself and to P-No 4, P-No 3 and P-No 1 base materials.
