The answer to the first question, as has already been stated is yes.
As for QW-409.11: That variable is not applicable to GMAW or FCAW. If you look at QW-255 (the applicable chart for GMAW & FCAW) that variable is not listed; so it's not applicable.
Charles.
I have to agree with most of the responses. Hopefully my two cents won't confuse the matter for you.
If you look at QW-255, as you were doing, it references QW-409.2, which states that a change in trasfer mode is an essential variable. However, unless you know QW-409.2 off the top of your head, the table itself doesn't say how it applies, so you have to go look at QW-409.2 to see what it says. I think that a lot of people get confused there. The table is just shorthand for what the paragraphs referenced address. They aren't actually addressing the variable or limitations in the table itself.
I also agree with those that said that only a change from or to short-circuit transfer from any other transfer mode is an essential variable, but changing among any other transfer modes besides short-circuit (including pulsed) can be done without requalification.
There are a lot of things that Section IX doesn't address, so you just have to know that if it isn't addressed, it isn't prohibited. So QW-409.11 isn't addressed in table WQ-255, so you could do anything you want with regards to power sources, and ASME IX wouldn't care (for GMAW). WQ-409.11 (as far as I can see) only applies to Stud welding.
This is just to state what has been said already. I look at spray arc, globular arc and pulsating arc as a group of one. Any change among this group does not require requalification. A change from this from this group to short circuiting arc requires requalification. To change short circuiting arc to any one of the group also requires requalification.
GRoberts makes a good point about QW-409.11 as a variable for QW-255. Not a reason to requalify.
Regards, Donnie Mann