As for your question, I'm not sure that you will find the wording " calibration of welding machines" in the AISC audit requirements. They slip it in as requiring "all equipment, and or gages used in inspection, that can effect the quality of the product must be calibrated"...or some such wording. They can lump a whole bunch of equipment into this as the auditor sees fit...I think the wording is too loose and vague because they could really expand it to mean everything between the front door and the back door needs calibrating as it effects the product in some way.
My memory isn't what it used to be but I think it falls under Audit policy #15...I will try to look it up for you when I get a few minutes.
OK Look in audit policy # 15, 15a and in the Building Standard Element # 14...this deal with the calibration of equipment and tools used for inspection.....