Good Day,
You are correct: 1) that joint cannot be used with FCAW in the Horizontal position; 2) that is the test to use for welder qualification; and, 3) you are missing something.
You are three for three. Looking good.
To the issue, Keep Welder Qualification Exams Separate from Production.
Once the welder is properly qualified to D1.1 standards they are qualified to weld any APPLICABLE PREQUALIFIED joint within the limitations of D1.1. There are limitations to position and joint design and electrode size, and welding parameters, and many other factors within the Prequalified WPS limitations stated in D1.1.
All of that has nothing to do with the welder being qualified for the work using that particular weld joint in the 3G and 4G positions. And, if a fabricator HAPPENED to qualify a WPS in the horizontal position using FCAW then they could indeed weld in that position using FCAW. It just is not prequalified.
Sure, Prequalified WPS's MUST be written and welded to within all of the applicable limitations of D1.1. And yes, the welder qualified per that test IS qualified to weld in ALL positions with FCAW. It all works together perfectly. You just have to keep certain parts separated from other parts when trying to understand how it all works.
Hope I cleared that up. Hopefully others with better communication skills will chime in.
Have a Great Day, Brent
Not sure actually what you are asking.
So I'll try to help Brent and toss out some information and hope it sticks.
You are testing your guys with Vert and overhead... So there is no need to do horizontal test right?
The Prequalified Joint (Figure 5.1) that is closest to the test assembly is B-U2a... Which is not prequalified for horizontal welding with ANY PROCESS. It's not just Flux Core. Gravity is mean, and a V-groove like that will have issues ...
So typically for horizontal grooves used in production a WPS is produced with a single bevel. (See B-U4a) or something similar.
So the moral of the story is this: If your welders qualify on Vert and Overhead with a V-groove, they are qualified to weld horizontally on a prequalified B-U4a without further testing.