asme ix welder qualification

huangyhg

asme ix welder qualification
hi,
i require to qualify submerged arc welders to asme ix using process single wire (121) and tandem wire (123. although the process and filler will remain the same does changing from single wire to twin wire become an essential variable. if qualified on twin wire does it automatically qualify him on single wire?
thanks
i'm not sure what the 121/123 designation indicates if the filler is the same.
but it looks to me like the heat input, preheat, and possibly polarity would vary, which are all supplementary essentials.
my apologies for not making it clear,  121 & 123 process as defined by en iso 4063.  
looking at this again, i see i mis-read the original question- my response was concerning qualification of weld procedures, not welders.
qw 401.3 will explain the requirements for changing supplementary essential variables.  number of electrodes for saw is a supplementary essential variable.
my mistake, i did the same thing as jstephen!
qw 300.1 limits welder qualification based on essential variables, and gives no mention of supplementary essential variables.  i would not think the welder would have to qualify for single electrode, but i would be curious to hear if anyone has a more definitive answer.