header pipe-pipe butt welds
 

Hey, I was watching the show Musclecar. They had these cool lil inserts to help the butt welds they used for their custom header they were making for Dana White from ufc mma. ANyone seen it? Know where to get those?

like this, but not at 90 degrees?

http://www.northerntool.com/images/p.../153807_lg.jpg

I meant they had these insert that go between 2 pipes that would be butt welded together. It was there for more strength. It was pretty cool, I wonder where they got those

this is the only thing I use. any kind of insert will screw with flow more than a weld will and will not add much strength as the weld is still just in the one place, just practice and they will be plenty strong.
http://www.icengineworks.com/1625TTWCS72dpi.JPG

Edit,
backing rings are also an A+ idea as you dont need to back purge,
like this

^^ Those were what I was looking for.

They are for people who don't know how to weld (ie. those on MuscleCar). Consider that they restrict the internal diameter of the pipe and cause a disruption in the airflow.

Just tape the seam together with masking tape, tack it in a few places, and then weld around it. Keep your current low so you don't penetrate into the tubing.

Darn, have you guys seen this episode i'm talking about? I'm not a big fan of american muscle cars, but I see the work they do on there, and it looked real good to me

Yeah, well, the restriction didn't seem too bad for the added rigidity of the manifold. I thought it was pretty cool. A well penetrated weld could have restricted flow more. I guess it's the line you draw of having a good sturdy manifold vs a well flowing one. I'm thinking of over reinforcing it when you could have a better flowing manifold that still holds up . I'll post it if I ever find the part I am talking about

Only excessive penetration will cause issues with flow, not a "well penetrated" tube. That is where some of the skill comes from in welding; knowing how to control heat and filler to get the correct amount of penetration. There will be no problem with strength if the manifold is welded correctly without any inserts.

I've seen that episode of Musclecar a few times and do enjoy the show. But some of the stuff they do makes me wince. Other stuff they do is amazing.

They are not for added rigidity, they are to prevent slag inside the pipe. if you are new to welding stuff like this you are likely to use to much amperage like arron said giving you a lot of slag on the inside. They also make it so you do not need to back purge.

If you want to avoid backpurging, then use Solar Flux. It's a whore to clean off afterwards, but I guess that wouldn't matter for exhaust tubing.

Its actually extremely difficult to match the perfection of backpurging or using flux on the back side of the tubing. Even if you use extremely low current, there are some spots that have only slight "full penetration." In this case, if the other side of the weld is not protected, even a very small amount of "sugaring" of the weld occurs, or oxidation. This is porous and has thousands of tiney stress risers. Even if it is a small section, that is all it takes for a crack to form, and crack propogation is just a step away. If you're looking for something that is reliable, protecting the back side of the weld is the only way to go. There are too many variables between tube manufacturing, fabrication, weld preparation (including deburr), to the actual welding process to ensure with 100% confidence that you will not create something that is too thin to not "fully penetrate."

I have personally created very nice looking welds on the surface, and even at a good glance at the back side, but when I cut the tube apart and stared *really* closely, I saw evidence of sugaring. Only the smallest amount is what it takes; its like a tiny little chip in your windshield.

Just my $0.02. Maybe I'm just an anal fuck.

Yeah, but we're talking a set of headers, not necessarily the space shuttle. I'd rather accept a tiny bit of imperfection on the back of the weld then stick in a sleeve. Or, just backpurge or use flux.

But you're forgetting not every one has the skill you do. I don't but I'm working on it. I have used Backing rings on steal pipe, pipe as in ¼" thick steal pipe I was told by some one who has done that as a job for the last 26 years that he still uses them. but then pipe is a lot different than exhaust tube.

I think the point here is that there are better methods, like back purging or using flux on the back side of the weld.

If you are MIG welding, there is no hope, you are probably going to get slad or over penetration anyway, because the wire is pushing the molten metal in.

There is always more than one way to complete a project and these clamps are a good alternative to welding. I wouldn't worry about decreasing the maximum flow rate of the exhaust. I would worry more about protecting the bare steal finish to increase the life of your creation. VHT makes a nice bake on ceramic spray paint.

Wrapping a pipe to hold the heat in decreases the effective inner diameter of the pipe and reduces the flow rate. It also causes the metal to fatigue faster, carbonizes the steal, and retains moisture. Wrap isn't used by any professional racers.