Ok mraschis, I understand what you are saying and D1.1 also has similar wording giving limitation on the maximum size single pass weld to be placed, but where in the Qualification of a Welder does it say or imply that the 5/16" called out in Fig 5.21 says that the 5/16" fillet weld has to be placed in one pass? Why can't the welder use several small stringers to get his 5/16" (what I'm saying and/or asking is that the welding symbol shown in the Fig 5.21 only says 5/16", and nothing in the tail to say it has to be done in one pass)...
I think the confusion is that you're getting the WPS and Welder Qualification testing requirements mixed up.
For Fillet weld WPS qualification:
D1.5:2008 Clause 5.10.2.2 Fillet Weld Qualification Soundness Test. <snipped first para> (1)"A fillet weld macroetch test shall be made for each WPS and position to be used in construction. One test weld shall be the maximum size single-pass fillet weld and one test shall be the minimum size multiple pass fillet weld to be used in construction. The two fillet weld tests may be combined in a single test weldment or assembly."
Does this make sense or am I all wet?