Here is my experience, I am currently employed as an inspector at a medium sized petroleum refinery, and I have also worked pipelines and new construction in the petrochemical industry.
To begin you want to make sure you are a proficient plate welder in all positions; SMAW (Stick) is probably the most common process for pipe. A double vee groove, open root with approximately a 1/8” gap and a 3/32” land on 3/8” carbon steel plate with a E6010 root pass & hot pass and E7018 fill in a is a good place to start.
When I started in 1985 with the exact question you are asking our instructor had us weld many different sizes but mainly we practiced on 6” sch. 80, E6010 root pass & hot pass with E7018 fill in a 6G, (45 degree position), the smaller diameter sizes are more difficult to weld in the beginning because you are always changing positions as you weld.
Practice, practice, practice, that’s the key to success, once you get good at a process/size change to a smaller diameter until you can weld 2” sch. 80 at a 6G proficiently, a local community college or shop with a good instructor can save you allot of time and show you many tricks of the trade.
Most all of the pipe tests I have witnessed are in the 6G position so you will want to master that position, where I work most of the shop welds are rolled on pipe postioners and the field welds are usually 5G or 2G. We also do quite a bit of GTAW (TIG), FCAW (Flux Core) and GMAW (Solid wire feed) on 9 chrome, 300 series stainless, Monel, inconel, etc.
You motioned high pressure piping, are you talking about pipelines, boilers, petrochemical, nuclear? Pipelines are mainly larger bore; 6” and up, if you are talking about boilers and/or the rest it is range of sizes and processes but mainly SMAW and GTAW, if you learn to weld the smaller stuff you will have no problem with 6” and up.
Good luck!
Thank You, I have tried 2" pipe with 6011 root and 7018 fill and liked it alot,I didnt have much trouble catching on. I've had lots of experience with plate in the same set-up you mentioned.I am mainly concerned withoil and gas lines (I live in Nova Scotia and a large natural gas plant is going in shortly, part of the sable Natural Gas project) But thanks for the answer, And I will be sure to start focus on that process more and like you said pratice,pratice,pratice.
If you get really good at stick you might try and see how you like small bore TIG, start on 4” or 6” pipe and work your way down to 2” or smaller, get to where you can TIG 100% completely out a 2” carbon steel schedule 40 or 80 at 6G. After that start into stainless, 100% TIG. It might be hard to find someone with good TIG skills to show you how but keep looking for someone, ask every question you can think of.
If they are building a NG plant near you there will probably be quite a bit of TIG small bore, most of the top hands will do the TIG work. I personally would want to be in a booth welding small bore than in a ditch on a pipeline.
Good Luck to you!
Actually I have done some Tig and actually did a test coupon (3/8th plate,1/8 root opening) just messing around in shop. I did root ,fill ,and cap 100% Tig and it turned out well...and passed a bend test. Thanks again for your responce.
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