TIG backside purging advice? - Lateral-g Forums

funcars · #1 11-23-2010, 10:24 AM

After doing some stainless exhaust welding without back purging I know I need it for the next effort. Would probably be very good for aluminum tubes as well. Doesn't seem to make as much difference for mild steel. I don't want to invest a ton of dough, but I need something functional. I do have an extra flow regulator/meter if that helps. Ideally I would like to have the flow turned on and off by the welder. One other issue is that I am constantly turning and moving the tubes to get torch access so the faster and easier to connect (or rotate without disconnecting) the better.

Any ideas, pictures or links I could check?

Thanks

The WidowMaker · #2 11-23-2010, 11:06 AM

the extra flow regulator will work perfect if you can hook two up to your bottle or you have an extra. my single regulator had an extra port and i pulled a line off of that for my purging. although it is regulated by the single regulator, i installed a valve to cut down flow once the inital purge is done. i leave it cracked during welding to make sure its good.

ive seen some cool plugs that would make swapping between tubes really easy. i didnt want to invest a ton of cash so i just taped up the ends. i just poked a couple small holes in the opposite end from the purge line, and started welding when a lit match would extinguish itself. worked really well and the difference was huge. it made the biggest difference when i had to fill a couple small holes that i couldnt do with a fusion weld.

just an opinion from a novice. id love to hear what the experts do.

417 Motorsports · #3 11-23-2010, 11:02 PM

I have got to try this setup, i have seen it done many times but always seen to forget to try it.

**GregWeld** · #4 11-23-2010, 11:36 PM

Nothing worse than "sugar" on the backside of a stainless weld... ALWAYS back gas when welding SS... no matter what it is if at all possible. You can make up a variety of back gas attachments - tubes - traps etc. - or just purge it if it's a tube like a header etc. It's best to use a dual flow meter... or you loose control and waste gas...

funcars · #5 11-26-2010, 10:43 AM

Does a dual flow meter have two separate circuits? I'm trying to understand how it is set up. I have one gas line that runs through the welder and my regulator/flow meter is between the gas cylinder and the welder. Would it work to have a separate tee and 2 flowmeters after the welder gas valve? Are there any schematics of set ups that would work?

Thanks

**GregWeld** · #6 11-26-2010, 11:05 AM

Go to your local welding store, take your current rig (just remove it from the bottle) with you.... tell them what you're trying to do. They'll help you set it up. Most all the welding stores I go to have lots of plumbing and adaptors for different regs etc. Since none of "us" can see what you're working with it's pretty hard to try to design something for you and tell you what you need. A quick trip to your local experts is going to get 'er done and save you lots of time and hassle.

funcars · #7 11-26-2010, 03:42 PM

Thanks - I'll try the local shop where I get my gas. It's a good idea and they are probably very familiar with typical syncrowave machine set-ups and may have some other good guidance for me.

RS_Customs · #8 11-26-2010, 08:54 PM

I setup a back-purge on my buddies welder when we were building a turbo manifold that was very crucial. I looked at a lot of thread and ended up using 2 regulator and a t-fitting like this one. It allowed us to completely flood the part without affecting out regular flow rate on the tig torch. We would crank it up and then depending on the amount of un-welded areas turn it down to anywhere from 5-15. Remember, argon is heavier and will settle and push air out. You don't want a large amount of flow past where your welding so as to suck air in through a vortex like affect. Tape works in a pinch if your welding far enough from it that the heat won't turn it into goo. We used stainless sheet metal and tacked it on both ends and one had a hole for the hose. We used 3/8 id fuel line from the auto parts store. Handled the heat good and is cheap. Practice on something first. I spent a week learning how to do this, but we were also working with thicker metal and penatration was hard to get without overheating it.

Weldingweb is a great place for welding info. Here is a link to a back-purge topic.

Here is a picture of the almost finished manifold.

Good luck on the project and again.....practice first, lol.

Robert

Big-Head · #9 11-26-2010, 09:21 PM

If its 16ga stainless, you wont need to back purge. Just make sure you use .045" filler and keep the machine at 55 amps. Its all about the heat in the weld. Use 347 stailess filler. You can accomplish this without crystallizing the back side. I do back purge collectors because there is so much heat in that one area.I also use stainless filler for ALL my mild steel headers and exhaust. 309L filler.

Hope this helps.