Anyone have experiance welding Low temp carbon pipe with ER70S-2?

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G'day all.I've just started a new job constructing a liquid natural gas plant, I'm struggling with the ER70s-2 wire we're using, or maybe it's the pipe material (all we are told is that it is carbon steel pipe, no specs what so ever).the weld i've just done is an 18 inch sch40 pipe, TIG root and hot pass, 7018 fill and cap, specs here for pipe fit up are 2.5-4mm gap, no landing, all hand prepped (in other words the prep can be all over the place), as a welder i'm not allowed to modify the prep.on the bottom section (4-8 o'clock) it seems very difficult to get a fluid, stable weld pool on the root run, i managed to scrap through this weld by welding hlf an inch, stopping, feathering and starting again, and to use 3.2mm (1/8th) wire on about 90 amps, and to walk the cup with the tungsten at around a 45 degree angle, it seems to continuously want to drop out of the prep with any more then a 3mm gap, normally i weld copper nickel alloy pipe with B3 Chro-Mo TIG root and hot pass, with 9016 fill and cap, and i haven't had this problem before.With the limited information i've got, anyone have any tips?Last edited by ttoks; 06-12-2014 at 04:38 AM.
Reply:No one has anything?Sent from my LG-P716 using Tapatalk
Reply:I have no personal experience with ER70S-2 but if it is anything like ER70S-3 I can understand your problems since I have the same with S-3.The weld pool is not fluid enough and the only way to get any sort of reinforcement is to up the current but if you feed a little too fast you get little pieces of rod that have not melted. This happens not only overhead but even going uphill.I am still trying to find out a consistent way of welding with this rod and it is starting to get on my nerves since I normally can lay down a decent root with ER70S-6.
Reply:Try S-6, runs a lot cleaner. Reduce your angle on the bottom,  drop a few amps, Sent from my SGH-M919 using TapatalkLong after the price is forgotten, the quality will remain.Both of my Poppy's 1954 Short Hoods -Third generation to weld with it and teaching a fourthSA 2## - Bought and sold more than I can remember or care to list, 8 in the shop right now
Reply:If he is welding on a project then he would not be allowed to switch to S-6 or deviate from the approved WPS.
Reply:Wps can be changed. It also depends on the language in the specs on what rod can be used.Sent from my SGH-M919 using TapatalkLong after the price is forgotten, the quality will remain.Both of my Poppy's 1954 Short Hoods -Third generation to weld with it and teaching a fourthSA 2## - Bought and sold more than I can remember or care to list, 8 in the shop right now
Reply:Agreed, however he would have to discuss the matter with the welding coordinator and then he would decide if and what changes are to be made.We both agree that the S-6 rod is a lot easier to work with.
Reply:Definitely, but most contractors I work for won't buy it. Save pennies now to spend dollars later in bad xraySent from my SGH-M919 using TapatalkLong after the price is forgotten, the quality will remain.Both of my Poppy's 1954 Short Hoods -Third generation to weld with it and teaching a fourthSA 2## - Bought and sold more than I can remember or care to list, 8 in the shop right now
Reply:Really? In Greece ER70S-6 is by far the most common carbon steel rod.I used to work at the Greek office of a very large welding consumable manufacturer and we did not even stock ER70-S3 unless we had a customer that required it.
Reply:All I ever see is er70s-2 unless I can talk someone into buying a sleeveSent from my SGH-M919 using TapatalkLong after the price is forgotten, the quality will remain.Both of my Poppy's 1954 Short Hoods -Third generation to weld with it and teaching a fourthSA 2## - Bought and sold more than I can remember or care to list, 8 in the shop right now
Reply:ER70S-2 is even more rare in Europe.For example Boehler and Esab (the 2 biggest European welding consumable manufacturers) do not even list it in their welding catalogues.
Reply:Okay, so I intend to bring up the use of -6 with the welding engineer's (probably pissing into the wind, but worth a try i guess), from what I understand the wire has to be low temp impact tested as it's being used in cryogenic lines in an LNG plant at temps as low as -168 C (-270 F), as well as everything else in the plant (up to around 550F), it's all done with -2, I've done some research, and I can't find impact test value's of -6 wire, except for one article stating that -6 achieves better test result's in low temp situation's, with no test result's included.So for those in the know, is this the case, does anyone have access to some information pointing to either -2 or -6 being better suited to a cyro pipe line?At this stage, the weld procedure states the use of -2, so that's what we use, but it's very difficult to get enough root reinforcement with the current fit up specs (and most pipe fitter's go more towards the 4mm root gap to save more prepping if they stuff up they're measurement's) particularly since there is ZERO allowable root suck back, and as we know the hot pass tend's to suck the root out a little on the bottom section of the weld.This is the first job i've been on where -2 has been used, everywhere else uses -6 in Australia from what I've seen for mild steel welding, and honestly if I could have 2mm root gap at the most, the -2 wouldn't be a problem.Last edited by ttoks; 06-14-2014 at 02:51 AM.
Reply:I am a welding engineer and there is no freaking way carbon steel is used in -168C.
Reply:Originally Posted by taz00I am a welding engineer and there is no freaking way carbon steel is used in -168C.
Reply:Although low temp carbon steel exists it does not go down to -168C.You are probably welding in some other classification which is still categorized as low temp but surely not -168C. At these temperatures it is either austenitic stainless steels or 9% nickel.Anyway according to SFA 5.18 the minimum requirement for S-2 and S-6 is the same and it is 27J @ -30C.
Reply:Parts of the plant may see -168, not necessarily what ttoks is welding on. Sent from my SGH-M919 using TapatalkLong after the price is forgotten, the quality will remain.Both of my Poppy's 1954 Short Hoods -Third generation to weld with it and teaching a fourthSA 2## - Bought and sold more than I can remember or care to list, 8 in the shop right now
Reply:Yes, maybe I was not very clear but this is what I meant.
Reply:Taz, i think your a bit of a keyborad jocky trying to prove how good you are by finding a detail you have minimal info on, and going full bore with your " expertise" just like 80% of the "welding engineers" ive had the plessure of having to work with, somone, somewhere decided to spend 17 billion building this place, im goi.g to place some faith in them knowing theyre ****, your credentials on the otherhand, are your claims that you know whats going on.Sent from my LG-P716 using Tapatalk
Reply:I could answer that but it seems I would be wasting my time.For me this discussion is finished.