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Up Topic Welding Industry / General Welding Discussion / 8" SCH10 316L Welds
- - By wolfram (*) Date 06-18-2009 04:13 Edited 06-18-2009 05:55
Hi all,
I am going to have a series of questions about welding 8" sch10 316L SS.
First question: how would you joint prep to produce a CJP weld? What I have done is use a slight v-groove, butt up tight, purge then fuse (autogenous) first pass at about 90 amps. Second pass (cover) is at about 75-80 amps with 3?32" 316L filler.
1/8",2% thoriated, 25/CFH.

Thanks,
Scott
Parent - - By Joseph P. Kane (****) Date 06-18-2009 11:35
Sounds good.  Are you going to purge?
Parent - - By Shane Feder (****) Date 06-18-2009 13:21
Scott,
It will depend on the position you are going to weld it in.
If you try and weld autogenous around the botton on a 5G weld you will have concave root - gravity is pretty unforgiving.
Regards,
Shane
Parent - - By wolfram (*) Date 06-19-2009 00:37
Welders,
Thanks for your comments.
Yes, The piping is purged. We would weld in 1G,2G and 5G positions. Pre-fab and installing. The issue I had was that when running the second pass that the weld color and appearance was poor. It hand brushed up OK but, the appearance was like it was overheated, slaggy looking. Base metal was blackened in areas. That is what did not brush out completely. The fusion root pass went in good with good appearance.

Scott
Parent - - By spgtti (**) Date 06-19-2009 02:04
  Make sure all the color is brushed off and you can hold your hand on the root (doesn't have to be completely room temp, just to where you can stand to hold your hand on it) before capping. 316 likes to be welded hot and fast, if it's going down dead and black your amps are too low and/or travel speed is too slow. Try using a larger diameter filler wire as this will give you more of a heat sink being that sch 10 is thin to begin with.
  If the wire balls up and runs away when you 1st strike up this is a good indication that its too cold. Thinwall 316 is a little tricky at first, I end up welding it more like an alloy than a stainless and it took me a few months to work out a technique when I first got around it.
Parent - By pipehog (**) Date 06-22-2009 14:21
pics please
Parent - - By Kix (****) Date 06-23-2009 14:47
Are you sure it's 8" and are you sure it's sched 10?  I'm not seeing that one on my pipe chart to check wall thickness.  Anything thicker then an 1/8" wall thickness I would v-groove and do it in more then one pass, but I wouldn't butt it up tight and autogenous weld it.  1/8" wall and thinner, you can but up tight with no groove prep and get it in one pass.  THis will help with the out of position welds and keep the bottom half from sucking back on ya.  If you v-goove and autogenous weld a 5g pipe, it will suck back on you in the lower quadrant no matter what the wall thickness is.
Parent - - By Shane Feder (****) Date 06-23-2009 23:31
Kix,
I think you are looking at the wrong chart.
B36.19 has 8" S/S Sch 5, Sch 10, Sch 40 and Sch 80
Regards,
Shane
Parent - By ZCat (***) Date 06-26-2009 20:36
Make sure you have a large 10 or 12 jumbo gas lens cup and you will have to use plenty of argon to get any good color on your cap.
Up Topic Welding Industry / General Welding Discussion / 8" SCH10 316L Welds

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