D1.5 requires single pass fillets of a certain size for base metals of a certain thickness unless low hydrogen requirements are met. The table, Table 2.1 found in AWS D1.5-2008 requires a minimum fillet size of 5/16 inch for materials thicker than 3/4 inch.

D1.1 has similar requirements as found in Table 5.8 of D1.1-2000 (its sitting here on top of my desk). There is a footnote that stipulates that the single pass requirement does not apply if low hydrogen practices are used.

Since I am signing the welder's test record, I can take some latitude in how I test the welder. It is my humble opinion that it makes little sense to test a welder using a procedure that does not demonstrate the welder's ability to meet the requirements of the code as a production welder. In this case it makes little sense to test a welder using 3/32 inch diameter E7018 if he will most likely be using 1/8 inch and 5/32 inch diameter electrodes on the job and he will be expected to deposit 5/16 inch fillet welds on thick plate. Likewise, it makes little sense to test a welder with 0.045 inch diameter FCAW electrode if he will be using 5/64 inch or larger when he works as a production welder. 

I try to test the welders using the conditions he is most likely to encounter in production. That may or may not be possible in all cases, but in my opinion it make little to give a test that allows a welder with marginal skills to pass only to see him fail when he takes on a production job. If he will be taking a position in a steel fab shop where he is expected to deposit 5/16 inch fillets as single pass welds as required by the structural code, then the test should require him to demonstrate the skills needed to do so. If he is taking on a position in a sheet metal shop where he will be making small welds on thin materials, the performance test should reflect the requirements of the applicable welding standard. The ability to deposit a 5/16 inch single pass fillet is not going to demonstrate the welder's ability to weld on thin materials.

I am straying from the original question, but I believe the question deserves more than a single sentence answer. There has to be a thought process behind the test given and the procedure that will be followed by the welder taking the test. The person administering the test should have a working knowledge of the welding standard that applies and he should take into account any technique requirements or limitations imposed by the construction code or code sections when developing the procedure used for performance qualification.

The bottom line is that for structural welders, I require the 5/16 inch fillet weld be deposited in a single pass.

Best regards - Al