TIG weld stainless exhaust purge
 

So getting close to a point where I will need to build my stainless exhaust.
I dont really have a way to easily setup a purge.

Since its not structural - If I tig without a purge - any issues ? Thoughts ?

This thread says --- yES .... NO ..... lol

https://weldingweb.com/showthread.ph...out-back-purge

Re: TIG weld stainless exhaust purge
 

Back when I was working, if it was a certified sanitary piping system as used for dairy or pharmaceutical applications it was purged. Otherwise every other general use weldment was tig welded without worrying about the inside of the piece.
I wouldn't worry about it.

Re: TIG weld stainless exhaust purge
 

Thanks - kind of the way I was leaning.

Re: TIG weld stainless exhaust purge
 

We have miles and miles of piping at work....every piece is purged while welding...on stainless it will "sugar" on the inside if not purged...may not matter on exhaust

Re: TIG weld stainless exhaust purge
 

Thx mongocanfly ....

I havent welded much stainless ...... but the stainless I have joined I do see the sugaring .... but figured on the 3" exhuast going out --- should be strong enough with the amount of weld to hold up ...... just wanted to see if there was a consensus .... seems most guys in trade say backpurge and do it right ...... but most guys how just hobby say they have had no problems for just exhaust .....

Re: TIG weld stainless exhaust purge
 

I did the maintenance purchasing in a fruit juice/apple sauce plant that every sanitary stainless tube weld was purged. The guys doing the welding and the outside contractor's welders had plugs to plug the ends of the tubes with one plug having a hole for the hose to connect to.

I'd say that both Gippetto and Mongocanfly will say that it is far more to prevent contamination of the product that the line carries than appearance. Sanitary stainless welders (the people) lay down some of the prettiest welds you will ever lay eyes on though.

Re: TIG weld stainless exhaust purge
 

IMO:: If your gonna go to the expense to use Stainless, do it right..
A brass y at the bottle, little bit of hose, roll of tape, bam your done..
JT
From
SC

Re: TIG weld stainless exhaust purge
 

As a retired millwright/welder in a brewery.....when welding stainless that product went through it was purged, If it was for other then human consumption, it was not purged. Nobody sees the inside of exhaust pipe and the strength of the weld is not effected. Extra effort is often wasted effort.

Just my humble opinion....

Re: TIG weld stainless exhaust purge
 

I just finished mine. I did it in 409 stainless not 304. I did not purge it at all. Almost no sugaring inside ( you won’t see it anyways) I did my research like you. You do need a tri gas( not cheap) if you are doing it in 304. All the supply shops would have to order it for they did not have it at hand. I was happy with the 409 ss , should last 20 years probably more for most of us do not use as a daily driver. 304 ss should have been about $500 more. But it all depends on you on which route you want to go. Don’t get me wrong I love 304 ss . But I put the extra $500 to other things for the truck. Hope this helps

Re: TIG weld stainless exhaust purge
 

I build dry ice manufacturing plants. Almost all the piping is stainless. Some up to 3' in diameter. It is not practical to back purge such a large pipe. I will have as many as 30 TIG welders on site at a time. They all use Solar flux on the inside of the weld. It's not super expensive and goes a long way.
https://www.amazon.com/Harris-S0FB01...Sn5QhoCH8EQAvD

Re: TIG weld stainless exhaust purge
 

you do not need trigas to tig 304 ss. I use straight argon wit a cerrated tungsten and it works fine. I do not purge its too much hassle and the sugaring is minimal if your fit up is good. fit up in the joints is much more important. I have done quite a few ss exhausts in streetrods. a compression bender puts more restriction in the pipe than not purging.

Re: TIG weld stainless exhaust purge
 

Thanks for that info about the tri gas. I did not know that. I learned something today.

Re: TIG weld stainless exhaust purge
 

Always use a as brush designated just for SS. If you use it on carbon steel then on ss it will rust because it will deposit carbon on the surface. I will second a good fit and straight argon. Also I brush my tacks and weld while it is hot, it shines much easier. Keep a sharp tunston and clean surface with flapper wheel or wire wheel and the weld will flow much better. Purge is not needed for exhaust, yes it will sugar, but not necessary. The sanitary tubing (.065 wall I think) is only washed together, no rod needed with a perfect fit. If you have a gap on one side, more than likely it will pull to that side after welded. Here are a couple pics of 2" sanitary tubing I welded up last week and just hand brushed right after welded. Good luck
Mac

Re: TIG weld stainless exhaust purge
 

:metal: Good enough for me.

Re: TIG weld stainless exhaust purge
 

Awesome. Yes will be the cheapest SS 3" I can get on ebay. Just something a bit better that other options.
Nice setup.
I wont be able to run twin tubes at least down each side.
Ill either have to cross over behind trans and join tpo a single pipe ..... or run both down the drivers side.

Any thoughts on that ?

Re: TIG weld stainless exhaust purge
 

Compression bender ? Just mean the bend of the tube ?

Re: TIG weld stainless exhaust purge
 

Nice ..... Im really enjoying TIG ...... when I finally get the truck built Im going to put more time into TIG - stainless or aluminium fence gates ... so on.

Re: TIG weld stainless exhaust purge
 

409 ss is what you look for if your not going with the 304 ss its the only 2 choices for stainless ,as for the way you want to run either way is fine , going 2 into 1 you lose performance especially with a performance motor , but no one says you cant. Iam just trying to figure out your set up with out a picture to see why you cant run one exhaust tube on each side. let us know how you do.

Re: TIG weld stainless exhaust purge
 

Fuel tank on the passenger size takes up all the space ..... only 1" of clearance between fuel tank and hwere driveshaft will go .... only option would be outside of frame that side.

Re: TIG weld stainless exhaust purge
 

How about running the pipes along the underside of the running boards....like lake pipes and dump in front of back wheels. depends on ground clearance of coarse.

Re: TIG weld stainless exhaust purge
 

Had to google lake pipes :)
I think ground clearance should be ok unless I bottom out hard ... fuel tank is lowest point currently ... but still well above bottom of rims without tires ...

I'll find a pic ....

Be mostly concerned about noise. When I start it up with just the short headers on - sounds like a bomb.

https://www.jalopyjournal.com/forum/...pipes.1100132/

Wonder if t hat would help ..... #post6.

Re: TIG weld stainless exhaust purge
 

Dont have a great pic from backside ...... but this will give an idea

https://i.imgur.com/uPW0Yhjl.jpg

Re: TIG weld stainless exhaust purge
 

if you go to the local exhaust shop and they bend pipe for you, they use a compression bender. That bender wrinkles or reduces the pipe diameter in the bend, because the internal diameter is not supported with a mandrel. the mandrel bends you buy are bent with a internal mandrel or "pig" that follows the bender thru the bend and supports the diameter for smoother bends.

Re: TIG weld stainless exhaust purge
 

Gotchya. Thanks.
Was just planning on buying 3" straight and mandrel bend SS on ebay :) Cheaper than anywhere locally.

Re: TIG weld stainless exhaust purge
 

Yes that is exactly what I was referring to. You should have enough clearance for a resonator in front of your pipes or an internal baffle as was suggested on the hamb.