im planning to build my turbo manifold and im planning to make with my mig welder, do you need purge and using mig or is it only when you tig welding?

 

you only purge, when you weld stainless pipe and you want a perrfect bead!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boostedh22n770 &raquo;</TD></TR><TR><TD CLASS="quote">you only purge, when you weld stainless pipe and you want a perrfect bead!</TD></TR></TABLE>

Ok thanks for that.

You only need to purge stainless pipe so it doesn't suger on the inside of the pipe. Suger being the crusty black **** that looks like burned suger.
If you are making a stainless manifold I guess purging couldnt hurt. I wouldnt mig weld stainless though. Stainless is not very fond of being mig welded btw. I do it like every day and it's a pain in the ***.

 

What wire/gas are you using mr bear pig?

 

your welcomed! you must be a certified tig welder!

btw you dont backpurge mig welds.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boostedh22n770 &raquo;</TD></TR><TR><TD CLASS="quote">your welcomed! you must be a certified tig welder!

btw you dont backpurge mig welds.</TD></TR></TABLE>

No I'm not.

Duh because no one mig welds ss pipe Purging would probably help flatten out the bead on the inside of the pipe though. I just weld sheetmetal and plate all day what the hell do I know?

Burnthrough/suger on stainless is a no no where I work so I'm in experianced at full penetration ss mig welds


I'm using .035 308 wire with timix gas. Mostly outside corners and groove welds done vertical down on 11-18g.


Dont bother suggesting a different setup lol. That's all they give us where I work.




Modified by ManBearPig4silly at 2:49 PM 3/18/2007

 

ss with trimix sucks! your boss is a dummy

 

Yes you can weld mig on ss pipe, but mig is only used as a filler! not for bead or root, because of (lack of fusion) in the bead with (mig). I'm 6g certified in four different processes and currently in journeyman status! So you dont have explain to me what causes stainless to suger up! What causes stainless to suger is the pressence of oxygen,on the backside of the weld where this is no gas coverage.





Modified by boostedh22n770 at 2:27 AM 3/19/2007

 

There is a reason you don't see wirefeeds on pipelines....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boostedh22n770 &raquo;</TD></TR><TR><TD CLASS="quote">you only purge, when you weld stainless pipe and you want a perrfect bead!

</TD></TR></TABLE>

Are you saying you only purge stainless tube even with TIG?

Just we purge T45 tubing at work when making the rollcages..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bailhatch &raquo;</TD></TR><TR><TD CLASS="quote">ss with trimix sucks! your boss is a dummy </TD></TR></TABLE>

We use Lincoln welders. Make your own assumptions

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boostedh22n770 &raquo;</TD></TR><TR><TD CLASS="quote">Yes you can weld mig on ss pipe, but mig is only used as a filler! not for bead or root, because of (lack of fusion) in the bead with (mig). I'm 6g certified in four different processes and currently in journeyman status! So you dont have explain to me what causes stainless to suger up! What causes stainless to suger is the pressence of oxygen,on the backside of the weld where this is no gas coverage.

Modified by boostedh22n770 at 2:27 AM 3/19/2007</TD></TR></TABLE>

Awsome. Your first post was about as helpful and informative as this though.

Poop.

See? not so helpfull.

Anyway. Lay down some knowledge on us about the ins and outs of backpurging.

 

what you call welding i call that overlaying.





Modified by boostedh22n770 at 7:24 PM 3/19/2007

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boostedh22n770 &raquo;</TD></TR><TR><TD CLASS="quote">what you call welding i call that overlaying.

Modified by boostedh22n770 at 7:24 PM 3/19/2007</TD></TR></TABLE>

what are you, a union worker?

telling everyone how good you are doesnt help them a damn bit.

 

and youre just another heckler!

 

im done with this thread!

 

How informative.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ManBearPig4silly &raquo;</TD></TR><TR><TD CLASS="quote">How informative.</TD></TR></TABLE>

He's a journey man, thats all we need to know

 

Back on topic.

If I were mig welding a SS exhaust manifold should I backpurge? Tri mix? Argon?

How should a SS exhaust system be approached?

 

i have never heard of anyone backpurging when mig welding. but if it will work anything like tig welding it will only make the weld stronger. if you dont get any more info on it from any one else i would say that all you have to loose is some welding gas.

 

You near Kalamazoo?

Anyways here is my 2cents:

You can mig weld it if you want. I hope you have a machine capable of pulse welding or you will have a lot of spatter especially with SS.

Backpurging is a great idea and you should try it. Everyone here is obsessed with backpurging and I am not sure why. I don't do much pipe welding but this is only for strength under high pressure. Even the highest boost sytems are going to be like 50 PSI. That is not going to bust a joint. unless the manifold is under a lot of stress from weight.

If anything the full penetration is going to slow the flow down. NASCAR exhaust systems require no penetration cause of this.

Half of the strength comes from the size of the weld legs. The other half is how much penetration ther is.

 

I think half of the hype about purging is about the remote possiblity of the suger breaking off and getting thrown though the turbo.


THe other half would be weld strength since there are tons of problems with manifolds breaking caused by vibration, thermal expansion and the weight of the turbo. Keep in mind these are not balanced v8 engines with systems designed to have a very short life span.

 

I didn't think of any sugaring getting into the turbo, this would be bad.

I don't know much about manifolds how they are engineered but it seams that if you put a nice weld without any penetration than it most likely won't break at the weld. I have seen a few cars that their factory headers are known for cracking like the Grand National. The header and manifolds that I have seen broken are everywhere but the welds.

I definatley doesn't hurt to backpurge, I just don't think that is all that necessary.

This is coming from someone who doesn't know that much about the subject, jsut my 2cents.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RCautoworks &raquo;</TD></TR><TR><TD CLASS="quote"> He's a journey man, thats all we need to know </TD></TR></TABLE>

Journey ******* rules, I've got the greatest hits CD in the car right now. Any man that is a Journey man, is all right by me...

Backpurging is always a good idea, mostly for weld strength (ManBearPig had a great point about vibrations). However, if you don't believe strength to be an issue, there are ways to get rid of sugaring. For the outer areas of the mani, a mini-flap or carbide bit for a dremel works great. For the inner areas, a light media blast inside the piping will probably knock away any thing in danger of falling off.

For most of these home-built setups, yes, flow is important. But, these aren't highly engineered things, tuned to pulses and such. What is more important than flow is just getting the gas from Point A, to Point B. In such, if you don't have a purge setup, I wouldn't take a lot of money from your budget to make one.



Modified by Goullish at 1:42 AM 3/26/2007

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by arcboy &raquo;</TD></TR><TR><TD CLASS="quote">I didn't think of any sugaring getting into the turbo, this would be bad.

I don't know much about manifolds how they are engineered but it seams that if you put a nice weld without any penetration than it most likely won't break at the weld. I have seen a few cars that their factory headers are known for cracking like the Grand National. The header and manifolds that I have seen broken are everywhere but the welds.

I definatley doesn't hurt to backpurge, I just don't think that is all that necessary.

This is coming from someone who doesn't know that much about the subject, jsut my 2cents.</TD></TR></TABLE>

Part of the problem on a turbo application is that the manifold gets so damn hot. If there is no penetration the edges of the seam on the inside of the joint heat up faster than the rest of the piece. No pentration tig welds on schedule pipe manifolds typically split right down the middle because of this. Plus vibration is a bitch.