Preheating temperature in ASME IX

[Hang Suin]

Since I have to qualify procedure according to ASME IX for welding plate SA-204 Gr B in full penetration design, thickness 20mm and GTAW/ SMAW combination of processes, and given that this type of material needs preheating, I am reviewing the ASME IX, par. QW-406(1)(2)(3) in order to find the specific preheating temperature but the only one that I have found is if and when the preheating is considered as essential, supplementary essential or nonessential welding parameter. Please advise me where I could find a table that shows the specific preheating temperature for such a material.

[wgadmin]

Please note that ASME IX is not a code for construction but a code that gives instructions how to qualify a welding procedure. Preheating is a variable (as all of other welding variables like groove design, base metal grade, filler metals, electrical characteristics, etc) and thus the preheating temperature is upon the manufacturer (as are all of other welding variables) and it depends on a number of factors, such as the chemical analysis, degree of restraint of the
parts being joined, elevated physical properties, and heavy thicknesses.

Usually the construction codes (ASME VIII, B31.1, etc) give some practices that used for preheating as a general guide and thus if we consider that your construction is under the scope of ASME VIII then you could use its nonmandatory appendix R that suggests (as a general guide) preheating at 79 deg. C as you could see by the par. R-2(a) that matches to your case.