SCH10 1 1/2" pipe weld critique

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This is for a hobby and I have never taken welding classes and I don't do this for a living. I'm waiting for a new turbo for my audi so I'm finally gonna ditch the cast log manifold and build myself a tubular. The old one didn't let me run a real filter and I had some close calls with the mesh so this gives me an opportunity for a better turbo placement. I didn't take too many pictures. Things that i did. At first i was worried about sugaring the inside so didn't do a full bevel on the pipes. The welds looked cold and i was only using 55 amps and 3/32 filler. I thought the 3/32 was too large and cooling the puddle too much. I went with .030 mig wire and it was nicer, but the penetration was obviously no good. I don't have a back purge set up for the tubes and this is going in my own car so I didn't go for full penetration. I still wasn't really happy with the welds or the consistency or color. Next day i cut some more pipe and did a knife edge bevel. I did a few test passes with out filler to see that ceiling of where my current should be until you see sugaring on the inside. 80 amps seemed right on the money. Then i worked with the filler. at 80 amps, if i kept the .030 wire in the argon, i heat starts to ball up the wire. I went back to 3/32" 308 and was more aggressive moving it in and out and i was almost jamming the filler in. This seemed to work really well and helped with my consistency by actually moving faster.Should i crank up the amps some more? Adjust my torch angle? Do i need more post flow? The weld looks great but as soon as the argon flow stops, it blues up. I'm maxing out the post flow setting on my eastwood tig. I'm trying to get away with not back purging.  here you can see the inside sort of. Opinions?Last edited by Poopie; 05-02-2013 at 11:40 AM.
Reply:What's your gap?  I think 80 amps is tad hot. Try quatering the pipe, what I mean by that, do a 1/4 of the pipe at time, this way it doesn't heat up and sugar on you.. How big of gas lens you using? What's your CFM at?   I think 3/32 is fine for that, that's what I would I use.
Reply:How long are the pieces you will be welding for your car? If you can clean the inside of the weld area after welding, you can use Solar B weld flux for a back purge. Thats all I use for a backpurge on stainless pipe and it works well. In your case however, you will more then likely want to clean the inside of the welded joint after welding to remove the left over solar flux.If you use the solar flux, you can achieve full penetration on the welded joint which would be my goal.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:I would definitely listen to shortbus, don't camp out on one joint or you will get terrible results.  I prefer to tack most pipe 4 places, lets say 12-3-6-9 o'clock.  Weld from 3 to 6 then 9 to 12, then 6 to 9 and finish on 12 to 3.  Starting on the tacks makes it easier to get a nice puddle quick.I typically run 10-13 seconds of post flow and 1.5-3 seconds of pre-flow, a few more seconds of gas is much cheaper than having to redo stainless pipe because of insufficient flow.  The dark dark blue/purple makes me think you are too hot and/or going to slow and when the gas stops flowing it snaps to that color, also if the welds behind that are basically colorless that's a sure sign your too hot/slow. Whenever I tig I draw up a spreadsheet type thing on scratch paper and record every variable: heat, filler rod size, pre/post flow times, cup size, tungsten size, dabs of rod per second, etc. and only change one thing and note any differences.  Keep welding stringers on some scrap pieces until you get everything dialed then and it will be much easier .
Reply:I'd suggest wider bevel, knife edge land or close to it, autogenous root at lower amps, with full back purge or solar flux; then cap with second pass at 70 amps or so.  You will find it very difficult to get full penetration with your setup and one pass, and if you do, you'll overheat the rest of the joint.
Reply:Like Mr. Moose and snoeproe said, you need a backpurge so keep the inside contaminant free.  You can either use solar flux or gas, I prefer gas because that's the way I was taught and that's the way the owner prefers as well.You only need a 5-7 cfm flow to keep the inside clean.  On 1 1/2' pipe I would just tape over both ends, poke a hole large enough for the hose to go in, and put scotch tape over the joint.  When you are about to weld peel off the tape on that 1/2 or 1/3 or however much of it your going to weld.  I know its probably not the exactly correct way for some but it works just as well as anything else I've heard and tried myself but is very cheap, easy, and fast.Just make sure everything is clean, clean, clean before you start.
Reply:Thanks for the suggestions. I will work on getting a purge set up. in the meantime i made a little beveler. its quicker than getting the pipe pieces centered and cut on the lathe. I have a slot that i can adjust for angle and depth.
Reply:Nice jig!Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer