Sanitary Stainless Steel Welding

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Anybody out there have experience doing sanitary welds on stainless steel?Thanks in advance,Joe
Reply:What do you need to know and on what grade and thickness stainless are you going to weld.Brett
Reply:I am going to be welding some fittings on a couple of my homebrew kegs ...and will be doing the same on a conical fermenter.  The conical fermenter is where a sanitary weld is very critical.The stainless will be 308 or 316Thanks,Joe
Reply:What do you need to know I've built a couple of these. I recommend TIG if you can and a inside purge to get out all of the O2 or weld from the inside.Let me know what your exact question is.Brett
Reply:Yes, I have a TIG welder.  I guess the real question is: How do you go about creating a sanitary weld?Do you simply have to purge all the O2 out with Argon? ....or is there more to it than that?Thanks,Joe
Reply:You need to be able to control your heat and puddle so as not to get any sugar in the weld or on the backs side. The weld should clean up with a wire brush or a light acid paste. If you weld shines and has rich colors you should have a weld that would pass as good. If your going for 100 penetration I would purge with Argon. If your going to weld from the inside out then you shouldn't need a purge.I hope this helps and I answered your question.Brett
Reply:Brett,  thanks for the advice.The wall of a keg is thin (0.050") compared to the wall of the fitting being attached.  So I had to really learn how to control the heat. What I did notice was that the wall on the inside of the keg gets goobered up if i allow the torch to puddle the keg wall.  To alleviate this, I would lay the filler rod where the joint will be, start my heat on the fitting and then slowly move the heat over to the filler rod without actually touching the keg wall with the torch flame.  It seems to work pretty good that way.  I get very little goobering that way.  I don't require a lot of penetration on the keg.I am a little nervous about possibly screwing up the conical fermenter weld.  You don't want to have any crevices or cavities where bacteria can sit and harvest.  Also, the wall on the conical is 0.100".Thanks,Joe
Reply:Back purge is the way to go with this stuff. In the Navy all of the nuclear pipe butt welds required testing to ensure the back side of the joint was inerted to prevent what you are talking about. We typically used N2 as a back purge gas. The key point is getting O2 out of the pipe or container.
Reply:I dopn't do any stainless work but the term "sanitary" refers to making a smooth bead inside and out to prevent bacteria clinging to any notches or crevices.  When the bacteria count goes up for example in a dairy pipe or tank they have to sterilize more frequently.  For the welder this means that there must not be any grapes inside pipe joints!