prequalified welds

huangyhg

prequalified welds
ok, i hear the phrase "prequalified welds" and understand that the typical welds most engineers regularly specify fall under this category.  these are welds that have performed well historically and fall under a precisely defined procedure of execution.
however, i curious if any structural engineers on this board have had to deal with welds that were not prequalified.  what was the specific instance and how was it handled??
any general insight on this topic would be greatly appreciated...
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we always purposefully stay away from welds that are not prequalified because the testing required to qualify a weld is a pain and can be expensive. there are so many prequalified welds that you should always be able to find something that will work for your situation.
if you are reasonably careful, as seit noted, you shouldn't have to get outside the prequalified weld joint procedures given in aws d1.1.  most are prequalified for smaw, gmaw, and fcaw processes (stick, mig, and flux core).  if you specify a weld joint that is not prequalified, the shop will have to develop a welding procedure specification (wps) and have the physical testing done to qualify the procedure.  it's not difficult, just a pain to get it all pulled together.
take a look through the prequalified joint procedures and pay attention to thickness limitations, process limitations, and configurations that might give you problems.  tubular structures with t,k,y joints and some very thick sections can lead to issues as well.