I'd try either D1.3 or 9.1. The main difference between D1.1 (and most other codes) and D1.3 and 9.1 is the testing.
D1.3 has destructive tests. The test is to weld, put test into a vise, and pull it apart with vise grips. There's no tension readings or measurement of the remaining nugget as far as I see.
D9.1 is simply weld and look. No destructive tests at all.
I've had customers who want thin sheets (0.049 wall tube) tested to D1.1 standards.