Clause no. 8.4.8 and 8.4.9 are talking about the reduction is maxi. 50 Deg.C and addition of 50 Deg.C for preheat and inter pass temperature. Suppose, I would like to qualify a WPS and the welding test temperature is say 40 Deg. C(Ambient) for a thickness of 10 mm thick butt joint and the inter pass temperature was 200 Deg.C . In this case, what will be the range for preheat and inter pass temperature to be written in WPS.