Tips for butt welding exhaust pipe

[Can'tWeld]

Hi

I'm building a downpipe out of mild steel at the moment and hoping someone could give me some tips on how to make my welds better.

Pics:




Machine is a Clarke 135TE on 1 MAX, wire speed about 5 and a third, co2/argon and 0.6 wire.

I'm having problems in particular with maintaining a constant angle on the torch as I move around the pipe.

Also, should I be welding downhill or uphill? Finding that if I move downhill I can't see the joint very well because the torch is in the way

Any tips would be appreciated, I feel it's 'nearly' there but i'm not happy with it yet. Ta!

 

[windingroads]

To make it easy, hold the torch in one hand, use the finger and thumb of the other hand
to balance and guide the tip of the torch, ( ensure you use a welding glove )
weld down hill for about 3/4 of an inch starting near the top of the pipe,
then rotate the pipe so you can weld another 3/4 of an inch down to meet the first run,
this will let the pipe cool as you rotate and set up again.

If you can't get a 3/4 inch run that looks good enough, then try on some scrap pipe until
you get your welder set up to accomplish this first.
You can also weld as above on the top of the pipe, rotate and repeat, what ever you are
most comfortable with.
I takes practice, you need to know what your welder will produce at a given setting too.
Rollers are handy for production work,
so you just rest the torch on platform and rotate the pipe, straight pipes are required though a little bend is ok.

 

[HughF]

Downhill, overlapping hot tacks. You need to practice on plate of the same thickness

 

[Can'tWeld]

Thanks guys

Did some more on it tonight using the "Weld a bit, stop, rotate pipe method"...

Getting there I think, maybe I need to practice my torch movements to make it neat and tidy.

 

[Richard.]

A completely useless comment from me but it would be far neater with Tig.

 

[Can'tWeld]

A completely useless comment from me but it would be far neater with Tig.

True, but it'd also be neater without a 200 pound gorilla operating the machine, to quote AvE

 

[Sparkey]

If you have trouble seeing where to weld try angling your torch slightly to right so you can see where you're going...also when welding exhaust pipe like this you can weld with a bit more wire stick out wich improves visability too and yes you should move downhill...it makes it easier to weld and lets your weld flow nice and easy...maybe tweak the settings a bit so you will be able to produce a smooth continous bead
Sparks

 

[octo0072000]

what kind of mask are you using also do you wear glasses

 

[Can'tWeld]

what kind of mask are you using also do you wear glasses

I have an autodarkening one (and yes I do wear glasses). I think I've solved the visbility issue now by putting a bit more light on the work area and also by welding a bit at a time so I'm not covering the weld with the torch.

Leak-tested the new pipe today, it doesn't hold water (literally). Am I right in thinking that if I'm doing this right I should be able to turn out a leak-free seam every time with a single pass?

Gonna practice on some scrap tomorrow... noticed the penetration is still poor. Maybe it needs more power.

When it comes to re-doing the downpipe I think I'll end up cutting the sections out again and getting the fit-up perfect, rather than trying to grind back and reweld what I have, never had much luck with that.

Cheers guys, I'll go away and practice a lot more and come back if I'm still sucking

 

[octo0072000]

I have an autodarkening one (and yes I do wear glasses). I think I've solved the visbility issue now by putting a bit more light on the work area and also by welding a bit at a time so I'm not covering the weld with the torch.

Leak-tested the new pipe today, it doesn't hold water (literally). Am I right in thinking that if I'm doing this right I should be able to turn out a leak-free seam every time with a single pass?

Gonna practice on some scrap tomorrow... noticed the penetration is still poor. Maybe it needs more power.


When it comes to re-doing the downpipe I think I'll end up cutting the sections out again and getting the fit-up perfect, rather than trying to grind back and reweld what I have, never had much luck with that.

Cheers guys, I'll go away and practice a lot more and come back if I'm still sucking

you can buy cheater lens to fit on your mask i have one works better for me
as you have found more light is good
http://www.ebay.co.uk/itm/Magnifier...hash=item4ae8e75481:m:mIENNOCdlAjSBH4j0kGgk-w

 

[cliff366]

I've always found more power than needed and tack pause technique on exhuast pipes just done one for a mate when his fell off should have taken some pics but got another to do soon wi try and remember and post for you

 

[Sparkey]

I always find going uphill easier with less chance of blowthrough...

Really? That doesn't make sense to me...cos when you're going uphill you can't go as fast as downhill so you should have more chance to blow through...
And yes when it's done right your welds should be leakfree in just one pass...the ones i do at work are tested with air pressure and leaks are tolerated under 0,8 l but i always want to go as low as possible...just for the fun of it

 

[Richard.]

I would also try keeping it in position. The reason down hill welding isn't acceptable on a structure joint is it's a low penetration weld which for an exhaust is exactly what you need.
My personal way of doing it would be from the top to stop gravity doing what it does best.

 

[Richard.]

I'm no Mig welder though and I'd probably keep the Mig away from the job altogether to prevent me making a hash of it.

 

[trewjohn2001]

Are you leaving it too long between tacks? It should be possible on new good clean metal to stack a long bead of hot tacks without much of a pause. For patching bodywork it's almost like stacking cold tacks to stop the panel warping. After doing that I can pretty much guarantee having to go over the panel again to fill in pinholes.