Sour service application. Amine and some hydrogen. Welding up in the racks where you may not be able to TIG or out in a cotton field welding up a compressor bottle. Several of the mid-stream companies use this procedure. I test about 10 -15 welders a month. Fail rate around 90% the first time. The company I work for requires a 2 inch sch 80 and a 8 inch schedule 80. That qualifies you for all thickness and all diameters. With a SA200 somewhere on that machine is a place the 7018 will run. If they let you put in a 3/32 7016 bead. Kobe is the one most of the guys out here run. You want the land and opening to be a little wider than the bead rod. If you are running a 3/32 you want to be able to drop the 3/32 through the gap. Same with a 1/8. On the 6 or 8 inch sch 80 a 1/8 will be faster and the fewer starts and stops you have the better. Putting your tacks at 12, 3, 6 and 9 you should be able to run from tack to tack with one rod. Change the rod run to the next tack. A hint on the gap. If it scares you it is so wide, then you are about right. As for the land, some welders leave a smaller land and put the bevels closer. Others take a wider land and open the gap. On every welder I hav tested who passed this test on the first try, they all took a fat land and a oh my god opening. For 3/32" start at 130 and 45 and work down first then up to find out where the machine runs the best. On 1/8" 190 and 50 again work down then up. Most welders running SA 200 seem to be 190 and 40-45. Also be aware if there is a time limit on the test. The company I work for has one and it gets about as many as IP on the welders first try. If you are a fairly proficient welder, 3 or 4 coupons and you should have it down. It is more mental than anything when you get the heat figured out. And the heat on a SA 200 is the key. Let me stress again, somewhere on that SA 200 is a sweet spot for running a open root bead with 7018. Find it and master it. The welders I test, when they pass it, know how special they are. Good luck and let us know how you do. And dont be afraid to bust this test. There are some #1 welders who cannot do this. Again, a big part of it is mental.
BABRT's
Really detailed info, Big K. I do not know why they would have you run that procedure except to see IF you really can weld. I know alot of guys say how good they are welding pipe using tig root or 6010 root and you bring up 7018 as a root option, honest people let tell you if they have ever tried it and acknowledge it is tough. I had a State pipe certification where it was mandatory to run 7018 all the way out, so I learned how to do it...............now the same state gives you the option to use 6010 or 7018 for the root. Go figure. Some times I'll burn thru a 6010 root with my 7018 hot pass because I ground it too deep, but if the key hole does not open up too drastically, I just carry on. Usually passes x-ray.
It's not like I would want to run a 7018 root simply because it is harder to do especially when a tig root using E70-S rod is a sure thing, imo.
If you have to do a weld with PWHT you can either tig the root or 7018. SAMW offers some flexibility you cannot get with TIG. If you work where there is a lot of sour service or amine piping this will make sense. If does separate the welders form the weldors though. ANd it is nothing but heat control. You can fight it and fight it, and when you settle in, it almost runs itself.
BABRT's