You hit upon an important point Brent, nearly every welding standard used by industry here in the US require the WPS to be qualified before it is used for production. There are several methods of qualifying the WPS. The one most frequently recognized is by welding a coupon that replicates, or nearly so, the conditions required for production. The sample is examined visually and possibly some NDE before it is sliced and diced for mechanical testing. If the mechanical properties meet the requirements of the standard, the WPS is qualified for production. Then the welders, to be qualified, have to weld a sample using the qualified WPS. If they pass, they are good to go.
Folks in the cross country pipeline industry use downhill progression on a daily basis with acceptable results. After all, those pipelines don't blow up that often. All joking aside, they have a pretty good track record of successful welding considering the thousands of miles of pipeline that crisscross this country and others around the world. Actually, I think the "space race" is a waste of time and money. The government should simply put out a RFQ for a pipeline to the Moon or Mars and it would be built soon enough!
I often poke fun at the the acceptance criteria of a "quality" weld per API 1104, but one must recognize the hoop stress in the pipe is usually two times (or more) than the axial stress of the girth (circumferential) welds. So, if there is some incomplete joint penetration, porosity, etc., it is survivable. Downhill progression can meet the requirements of the acceptance criteria of API 1104. Downhill progression is acceptable to AWS or ASME if the contractor cares to qualify the procedure and the welders using that technique. However, the acceptance criteria is considerably more stringent when compared to API 1104, so the effort to meet the mechanical properties and soundness requirements are less likely to be obtained when testing to AWS or ASME.
Best regards - Al
I did a test last year on 1", vertical and overhead. When talking with the inspector at the end of my testing, paperwork complete we were talking about downhill in AWS and he showed me welder qualifications of a guy that did a 1" vertical downhill. Want to say it was using FCAW. Never knew of such a creature.
On a side note, when you get done testing do not chit chat with the inspector, hang out talking shop, run like the wind as soon as you find out you passed. I was charged for an hour while we talked about fishing, different weld horror stories and other non billable stuff. He was a talker too. Now when I test, "everything good?", Inspector, "yep", 2 seconds later truck throttle is on the floor rolling coal!
E71T-11 works well downhill. There are some not so good things about it, but not being able to weld downhill isn't one of them.
Hobart Fabshield 21b and Lincoln NR211 both E71T-11. Yes, that light slag on those and running downhill is good. Downfall of both of those is according to AWS they are only good for 1/2" and below. Although, Hobart says that their 21b is good for up to 3/4". Also believe it's not for seismic use. I do enjoy using that wire though, up or down.
No Seismic stuff, they stink if they ever have to be welded over with another process, and the thickness limitations.
Some of the mgfgs limit the deposit thickness based upon wire diameter.
But for what its good for, its good for it. Reminds me of a never ending 6010. 5/64" is my diameter of choice.
Hate the smell of the smoke. Im sure there is some bad stuff in there.
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