D1.3 is not contained in D1.1, but it is referred to, and D1.1 is referred to in D1.3. D1.1 is limited to steels less than 1/8" thick, and states that when metals thinner than 1/8" are to be welded, the requirements of D1.3 should apply. As far as I can see, there would be no basis for procedure qualifications for sheet metals in D1.1.
D1.1 further states that when used in conjunction with D1.3, (meaning using materials thinner than 1/8" with materials thicker than 1/8") conformance with the applicable provisions of this code shall be required.
D1.3 states that the specification is applicable to the welding of sheet or strip steels, or both, including cold formed members 0.18" or less in thickness.

Excellent information Thank YOU!!!!!!! I am currently reviewing and possibly re-specifying some in-house certs. I am using D1.1 as a guideline (material welded range is between 14 ga and 1/2") but was confused when the original weld spec/ WSP called on D1.1 mainly, but refered to D1.3. Not having a copy of either of these specs is holding me back even further but can be worked around for now.
In D1.1 Macroetch Criteria (4.8.4.1) it states for PJP fillets that "thorough fusion" must be present. I am a little taken aback by this as it does not call it out as 20% of Thickness or similar (.2*T). How is "thorough fusion" quantified?
Also, what it a proper menas of DT for Tee joints 3/8" plate? The outside CWI is breaking them with a hammer to see if there is root penetration. No guided bending, just folding it over with a sledge to expose the root. If this method is alright please confirm, if not I will continue with other means. Can this test be replicated for 1/8" and 3/16" plate?
Thanks again for the replies!!!!!!!!!!!!!!!!!

My lord, does this software need to be worked on. It's constantly asking me to login. WTF?