greek,
First, Welcome to the forum. Haven't seen you post anywhere else so suspect you to be fairly new here.
The first place I would check is in your print pack and contract documents. That should give you a break down for structural, decking, etc as to the code they expect 'ALL' various phases of the welding to be done to.
Then, see if they reference anything in particular from IBC especially sections 12 or 16. No codes for weld completion are called out but there are regs for stress, loads and other factors to be considered.
Also, what part does DSA play in this job or in the railings? Is there anything in their requirements as to the codes applicable for welding railing.
Question, are you talking about a 'grip' rail or just a barrier or gaurd rail. More than likely you are referencing barriers along an elevated walkway or balcony from the sounds of it. But your description still leaves something to be desired. And I don't think that size material will meet any of the load requirements from IBC Section 16 especially for public areas.
I believe if you qualified your people to D1.1 with small diameter pipe you could get engineers approval for what ever you do on the railing. Would obviously need an RFI to document approval.
Good luck.
EDIT: My bad. Just noticed the thread title. There will not be a D1.1 for GMAW-S. You would have to do a PQR then test all your people to it. Now, if your people are already qualified to D1.3 with GMAW-S then you may be able to get an engineer's approval for the railing welds even if they did not "pipe" qualify. Again, RFI. And, as Al said, may need to use backing rings for any butt joints. But if you are doing fillet welds in a square bar to round pipe, picket to horizontal bar, connection then you would not need any backing and several of the other D1.3 qualifying tests would work as well. Just my two tin pennies worth.
Have a Great Day, Brent