Every so often the EOR will specify a standard that, for one reason or another, is not appropriate. Most of the time it is simply that they don't know the fine details. I would point out the error to your customer and see what they say. Most of the time, since you know more about the welding than they do, they will ask for a recommendation.
I would look at the two codes you cited and, using the same approach, suggest qualification in accordance with the most appropriate parts of both codes (ie - thickness from D1.3, base and filler metals from D1.6). When it's said and done, qualification of a WPS is pretty similar from code to code, so you shoulkd be able to come up with a sound recommendation.
One time our customer specified that we needed to qualify a brazing procedure in accordance with ASME Section IX. The problem was they also specified the filler metal, which in this case was solder. They were inflexible on the filler metal and refused to accept that we were going to solder the joints. This went back and forth for a long time before the finally understood the difference between brazing and soldering. In the end, we used some of the guidelines of Section IX to qualify our soldering procedure.
Charles
Noel
You might want to have a look at ANSI/AWS B2.1 Standard for Welding Procedure and Performance Qualification
Techstreet describes B2.1 as follows :
"This universal qualification document is an excellent tool to ensure economical quality. Covers all welding processes and an exhaustive array of materials used in metal fabrication. Indispensable for those who design and manufacture non-code products but who may also be performing to ISO 9000. Experience shows Specification for Welding Procedure and Performance Qualification adapts to the requirements of ISO 9000. Spells-out requirements for the qualification of welding procedures and the requirements for the performance qualification of welders and welding operators for manual, semiautomatic, machine and automatic welding."
http://www.techstreet.com/cgi-bin/detail?product_id=91You might also consider AWS D17.1 Specification for Fusion Welding for Aerospace Applications,
http://www.techstreet.com/cgi-bin/detail?product_id=957620