Question about stainless steel pipe welding.

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I am trying to weld 6” schedule 10 stainless steel pipe without coloring it. I was told that I need to set up the purge to flow large amounts of argon. The person telling me this also said that he has seen people using oxygen regulators in place of the flow meter so that they can flow enough argon. Is this the way it is really done or is someone feeding me a line. Does anyone have experience welding stainless steel without coloring it and could give me a few pointers Thanks
Reply:Colors of stainless comes from the fact the material is still hot when it looses it's shielding gas. How hot it is determines the color you see. Often one possible solution to color with SS is simply deceasing the total heat input. That can be done some times by upping the amps and moving faster. It sounds backwards, but more amps and less time equals less total heat input, thus the area surrounding the weld doesn't get heat soaked and allows the bead to cool faster.  Another option is increasing the shielding gas coverage. If the weld stays covered in shielding gas until the area cools below that critical point, you won't have those oxidation colors. That might mean going to a larger cup or a gas lens. Just upping the flow at the torch can some times cause turbulence and different issues..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Pretty sure the only way you'll get one without any color at all is if you weld it inside an argon tent.Are you talking about no color at all, or just not dark red or grey?
Reply:Originally Posted by TimmyTIGPretty sure the only way you'll get one without any color at all is if you weld it inside an argon tent.Are you talking about no color at all, or just not dark red or grey?
Reply:Originally Posted by skipweidnerI am trying to weld 6” schedule 10 stainless steel pipe without coloring it.
Reply:Originally Posted by MikeGyver..why?
Reply:If possible do it in a argon tank or chamber then it will be pretty.12v battery, jumper cables, and a 6013.I only have a facebook page. https://www.facebook.com/pages/VPT/244788508917829
Reply:Standard practice is not with an oxygen reg, but with an inert gas regulator calibrated for argon so that you can purge with 8 times the volumn inside the pipe. You need to calculate that volumn, fill at high speed, then reduce to a maintenance flow while welding.It is inside the pipe that you need to keep within color, right?Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Originally Posted by zapsterEasy..Because nobody knows how to operate a wire brush.......zap!
Reply:This is a short informative article on heat tints (temper colors) on stainless steels.   http://www.bssa.org.uk/topics.php?article=140Last edited by HT2-4956; 11-26-2014 at 09:25 AM.
Reply:Colour Formed Approx Temperature Cpale yellow 290straw yellow 340dark yellow 370brown 390purple brown 420dark purple 450blue 540dark blue 600 What about crusty gray?12v battery, jumper cables, and a 6013.I only have a facebook page. https://www.facebook.com/pages/VPT/244788508917829
Reply:Ive used an oxygen reg for long  large bore (12"+) runs on chrome and stainless. For 6",  a flow meter should be good.Long 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:I've always understood those temper colors (on stainless) to be a pretty reliable indicator that the stainless was not over heated (and there by sensitized to subsequent corrosion) from welding.   I can't recall ever hearing or reading any thing about them degrading the materials corrosion resistance.   Crusty grey on the other hand indicates that way more heat than necessary has been put into the piece and there's a high likely hood that you've caused the chrome to form other compounds (like carbides) which will tie it up and make it unavailable to form the normal chrome oxides that give the material it's corrosion resistance.   When it comes to general industrial process piping or structural work I don't brush my welds to get rid of them.   And I can't recall ever catching any grief for doing so.   If nothing else I look at it as adding a little color to what would otherwise be a drab thing.   When I see those colors that MikeGyver leaves on those manifolds he does I take it as one more indication that he's doing some really high quality work.
Reply:Originally Posted by zapsterEasy..Because nobody knows how to operate a wire brush.......zap!
Reply:You should purge enough to displace 3 - 10x the air inside the pipe.  After that, you only need to purge at a rate to replace any leaks.  Argon tends to be heavy so bleed it out the top.  I do a quick back of the hand calculations.  Shoot for 5x purge, then, If its something like a pipe, with joints temporarely taped, I might turn the purge down to 5-15cfh.3x is typically acceptable, 10x if you really want the insides looking clean.  Really depends what the insides look like.  A simple piece, like a pipe, where you ware welding near the bottom edge, 3x.  If the insides are "complicated" you need to purge a bit longer.  Imagine filling the object with water and getting all the air bubbles out.As far as the front side coloration, there's plenty of discussion about it.  In a pure argon tent you will have nearly zero coloration.Typically, a more practical thing is to polish or passivate afterwards.  There are some portable passivation tools that you can use if you can't dip the whole thing.Walter SURFOX is one such tool.  Expensive... Budget $2000 - $4000.  http://www.surfox.com/Polishing stainless is a royal pita.  Maybe a 120 grit flap wheel to get you close.  More than that and you will leave big scratches.  Walter also has some pretty cool polishing tools (outside of pipe).  Again, Walter is like Metabo and Fein.  Expensive German stuff.  Mercedes, not VW.If you are going to polish, polish first, then weld, then blend and polish the welds.  Or better yet, buy the pieces with a polished finish, then weld, then blend and polish.Wirebrush.  It had better be clean stainless steel wire brush.  A cup style one on a grinder works well enough.  I believe scratching stainless can reduce some of the 'stainless' qualities.  I'm not sure how well stainless recovers from scratches (needs to rebuild a passivation layer).  I do have wire brushed stainless exhaust pipes that have held up perfectly.  So, it might be OK.The rule is to keep carbon away - that includes carbon steel (drill bits, wire brushes, steel wool etc.) and carbon dioxide (in air)Con Fuse!Miller Dynasty 350Millermatic 350P-Spoolmatic 30AMiller Multimatic 200Hypertherm PowerMax 1000G3Miller Maxstar 200DX
Reply:All our stainless pipe is pickled before shipping. everything is a nice pretty silver, no matter how hot you run.
Reply:Originally Posted by Showdog75If you were to wire brush my stainless tig welds I'd knock you into next week, lol. Proper stainless welds need no brushing tig or stick. As far as looks go brushing usually makes for rookie ugly welds.
Reply:Originally Posted by con_fuse9I believe scratching stainless can reduce some of the 'stainless' qualities.  I'm not sure how well stainless recovers from scratches (needs to rebuild a passivation layer).  I do have wire brushed stainless exhaust pipes that have held up perfectly.  So, it might be OK.
Reply:Thanks for the replies a friend told me about a job that requires no color or brushing. I can lay down a good weld but I always have a light gold color in my welds. I guess that running a large amount of argon in the back purge helps reduce heat. I think I will order a high volume argon regulator and see if it will help.
Reply:I'm curious what such a job would be...Welding/Fab Pics: www.UtahWeld.com
Reply:You're chasing unicorns. I've been welding stainless pipe for a living for 30+ years, you can put all the purge in there you want, it's not gonna affect the color on the outside.  Maybe if you put a couple of trailing argon cups on your TIG rig like they do with titanium...I would also like to know about this job your friend talked about.
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Reply:Originally Posted by MikeGyverWorrying that much about the color is a FAD, brushing it doesn't make the weld uglier or change the metal deposit in any way... it's still the same weld. The color of the weld is not a property of the weld, it's a property of the oxide on top of it. Sure it can be an indicator of problems, but that's all it is. Any exhaust parts are going to look entirely different after little service anyway.Going to great lengths to get pure silver welds is pretty nonsensical. If you need that you'll need to argon chamber weld it or just electropolish it afterwards.Now my solution isn't to brush it, it's to accept realistic coloring. But if gold or any other normal color isn't good enough for you for some strange reason then electropolish it or brush it.
Reply:Originally Posted by Showdog75I agree with you but my point is properly done stainless tig needs no brushing and imo it looks worse after brushing.
Reply:Originally Posted by MikeGyverRight, and again, accept the normal coloring you get. Silver holds no merit above a normal color like gold. Requiring silver because you think it looks better is nonsense.By the way many industries do require that you brush all welds clean (or otherwise remove all coloring).A weld's purpose is not solely to look good and be some specific color, it's to join metal. Small scratches from a brush don't effect a weld's purpose of existing. Worrying about stainless coloring this much is a fad for Instagram and all the ricer/fabrication groups (take it from a guy who's been there but was also into welding before doing stainless exhaust work and before that all became a thing).I think you might be the one who is mixed up about the stainless/titanium mix up because specific colors of titanium welds actually fail the weld under certain welding codes, while these same colors do not fail stainless because it is not nearly reactive or as prone to embrittlement due to atmospheric absorption.Experience, size of pipe, thickness, travel speed, cup size, amps. Just to name a few factors that affect the color of stainless. Get your puddle started fast and start moving, I personally use big cups on stainless for the color,  I am no pro nor do I weld for a living, just sharing what works for me