[TheForge] tig welding, 18 gauge 316 stainless steel, chemical fume hood

[Ries Niemi]

On Jun 29, 2012, at 11:44 AM, terry l. ridder wrote:
> 
> 
> 0. just how difficult is it to work with 18 gauge 316 stainless steel?
> need to be able to make bends, roll it, etc.
> 1. knowing that it depends on the individual who would be learning to
>  tig weld, what is a good average length of time for the training?
> 2. would taking a community college course work in tig welding be
> sufficient for what needs to be done?
> 3. what training would members of theforge recommend?
> 
> please feel free to provide insights that you may have.
> 
> -- 
> terry l. ridder ><>
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Stainless steel is tough, as opposed to "hard", but its pretty hard to work with as a result.

18 gage SS is a LOT harder to form than 18 gage mild, and you really need some pretty beefy machines to work with it.
Many of the sheet metal tools, like brakes or rolls, that are rated for 16 gage mild, theoretically will work 18 gage SS, but in reality, are usually too lightweight.

When you double the thickness of sheet metal, you quadruple the force required to bend it. 

I frequently work with 18ga stainless- and I use a 12gage brake to do it, and a similar rated set of rolls. Both of which are 4 times the weight, mass, and price, of those cheapo chinese 16 gage brakes and rolls. Actually, 4 times is probably not enough, in terms of cost. 

So, unless you are going to be doing a lot of stainless fab, for quite a while, you are going to want to outsource the bending and rolling and punching- The basic tools to do this are just too big, and too expensive, to justify for one job. A good 4' 12 gage finger brake can easily run 4 to 7 grand, the rolls more like 6 grand and up, and on down the line.

As for the tig welding- 
Tig welding is a hand/eye art. Some people take to it like fish to water. Some people NEVER learn. 
You either can, or you cant. 
I have hired probably 20 guys and gals over the years as full time tig welders. I prefer to have somebody with a 2 year welding degree- those people, of course, are fluent in oxy-fuel, stick, mig, and plasma cutting as well as tig- but the skills all buttress each other, and are all complimentary. That said, a "natural" could probably learn tig welding from a cold start in a 3 month, full time class.

18 gage stainless is very tricky to butt weld. Its thin, and easy to melt. Newer technology machines help a lot, though- for somebody who doesnt have a few years of tig welding under their belt, I would absolutely recommend a very good welding machine- preferably a new Miller with pulse, like a Dynasty 200DX. Yep, them puppies cost around 5 grand, new. But for thin stainless, that pulse feature is the bee's knees. 
It makes a huge difference. 
I have recently been helping a buddy doing brewery work- all the welding is on 16 gage, schedule 10 stainless pipe, and every weld must be perfect. He is a certified sanitary pipe welder, and he does amazing welds with the Dynasty. It still takes us a long time, is expensive and fussy, and we still screw up from time to time and have to scrap stuff. And between the two of us, we have been working with stainless for well over 25 years of accumulated experience.

Now, all that said, if you have somebody who is a good welder, and can weld oxy-fuel well, they can probably pick up tig welding stainless in a class. How long depends on the quality of the instruction, and the natural ability of the welder, but I kinda doubt its gonna be a few days.

And if you buy a good tig welding machine, and use a design that uses overlap welds, backing plates and angles, you should be able to fab up the 18 gage. It wont look beautiful til you do it for a couple of years, but it should be fume proof and sturdy.

But send out the bending and forming and punching- thats another 2-5 year learning curve, and cheap tools are only going to drive you crazy. A decent sheet metal shop to fab 18 gage SS can easily run 30 to 50 thousand dollars in tools. 

ries