Contact the Engineer to see which code he wants you to qualify to.
Al
Not knowing any specifics, I could make a guess that the code may be AWS D1.6, but it would be only a guess.
Farmin,
If you are looking for a document to exactly tell you how to weld them together, I think it'd be better e to search in handbooks or references in the library. You know there's no standard to tell you what to do, it just tells you how to do.
Regards,
Ehsan
John's suggestion of using D1.6 has an advantage of requiring no volumetric examination of the test weld. Fillet welds must be qualified separately from the groove weld, but the groove weld is required to verify the mechanical properties.
Still, it is the Owner's responsibility to state what welding standard is to be used. Usually, that responsibility is delegated by the Owner to the Engineer when the application is structural.
When in doubt, ask the customer.
Al