butt welding exhaust system

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Darren

Darren

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Hey guys I got a flowmaster 2.5 exhaust system that will need some welding is it ok to butt weld the joints in a few spots? Thanks
 
I butt welded some of my last system but I always wondered about for my new system. Good point about the header welding Dave
 
Shouldn't be an issue. I've done it with MIG and oxy acetylene and the weld is almost always stronger than the parent material.
 
I make rings of the next larger size pipe (1/8" larger) or "C"s (cut off a ring, then slice the ring to make a C of it so it slips over the pipe) of the same size pipe because I suck at butt welding............
 
Wow, all this full weld this and that makes me feel like a chump.

I didn't weld mine fully; from header reducer to 2' after full welded x pipe, so I can drop it out as an assembly when/if the trans explodes; or something else changes like it always does; it's clamped the rest of the way to and after the muffler 4 tacks on each tube after and exhaust hangars hold the rear exits. No fume issues.

Butt-welding exhaust is hilarious to me, but whatever. So is painting the underside of the car so it can get rock rash. I'm worn out from my build thread no one looks at because it's 'body work'; so I won't feel like I haven't "put in my time".

Good luck, hope you have a lift, and be ready for pinhole chasing all day. I'd advise doing the system in two parts tacked up so you can remove it and weld it up, and service the front section without having to struggle.
 
I don't clamp it, I weld on flanges so the exhaust is in sections...............
 
So I see no one on this thread knows how to butt weld correctly.
 
RustyRatRod said:
So I see no one on this thread knows how to butt weld correctly.
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I got the complete system tack welded in place. I have 5 or 6 butt joints to weld. I Grounded a slight point at both end of the pipe for the weld, and tried to get it as close as possible. " doing my best laying on my back with the car on stands.

What are you holding back Rusty?
 
Proper butt welding requires a very small gap to be left between the two pieces being joined for best strength and proper weld penetration. I have argued this before, but all the "experts" came out in force and said I was wrong. It's in any first year beginner's welding handbook as well as all over the net. It's no trade secret.
 
Makes sense.. I have heard that in the past also
 
RustyRatRod said:
Proper butt welding requires a very small gap to be left between the two pieces being joined for best strength and proper weld penetration. I have argued this before, but all the "experts" came out in force and said I was wrong. It's in any first year beginner's welding handbook as well as all over the net. It's no trade secret.
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When butt welding exhaust, a gap is not needed. I'm far from an expert, but from my experience, having a tight joint makes it a LOT easier for me to weld without shooting through and leaving whiskers on the inside or leaving pin holes. Doing it this way may not be as strong as welding a joint with a tiny gap, but we're talking exhaust here, not a roll cage or a multi-pass pipe/structural weld.
 
i vote that RRR is correct. BUT, correct butt welding also takes skill to do correctly!???
my welding??? weld it, pound it with a hammer to see if it falls off!!!!!
 
I keep my joints as tight as possible. wire speed up, heat down.....no hurry. Always have beautiful joints that can be ground off or left as is. Aluminized exhaust pipe can be tricky. If you leave gaps at the joint you will get a kind of "sugaring" on the inner surface.

Buy some pipe and practice before you start on your project. Something else MAY work better for you.
 
The best way to weld the two pipes together is to create a beveled groove weld joint. This is done by grinding a bevel on the ends of each pipe, then fitting them tight together.
 
To really do nice butt welds it should be done with a Tig torch and backed purged with argon. But most don't have the welder or the expertise for this. Also very time consuming.
 
I do not grind mine off. They look too damn good. I use a MIG. TIG is definitely best if ya got one and can do it.

My point is, if you have a good MIG welder and know how to use it you can do some pretty nice exhaust pipe welding. It does take time, patience and practice.
 
Ironmike said:
I do not grind mine off. They look too damn good. I use a MIG. TIG is definitely best if ya got one and can do it.

My point is, if you have a good MIG welder and know how to use it you can do some pretty nice exhaust pipe welding. It does take time, patience and practice.
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mig welded mine, tacked it, pulled it out in the floor, very small grinding to dress up. used the stitch method to keep from overheating .
 
67cudafb said:
To really do nice butt welds it should be done with a Tig torch and backed purged with argon. But most don't have the welder or the expertise for this. Also very time consuming.
Click to expand...

Voted best answer.
Some things are matter of opinion in my opinion. Ha.
 
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