Following the D1.2/D1.2M2003 aluminum structural code do i have to requalify a procedure and retest my welders if i want to start using preheat on an application that was not qualified with preheat. Base material is 1/2" T6-6061 using a 4643 filler,1/4" to 5/16" fillets with wire feed and tig processes. I'm telling these guys we have to use preheat to control their distortion probs and need to know if we're going to get put on hold for retest and the whole 9 yards.. Thanks ahead for any help in this case!!