Hello all, I'm making a new downpipe but i'm unsure how to weld the pieces of the tubing together, should I just butt them up against each other and weld around it, or is there a better way? I'll be using my cousins MIG welder (with gas). The metal is aluminized steel. I've never mig welded before but I have Tig welded some and have a pretty good Idea of what I'm doing, and of course I'll be practicing first on scrap metal from the left overs. Any tips? I plan on using the method where you do a number of spot welds on top of each other. Thanks in advance for your help, the search engine didn't result in much.

 

Nobody has any suggestions? Will the butt joints be strong enough? I've heard some people grinding a fillit along the edges to form a v cutout, and then weld in there, also, slip joints would probably be strong, but I don't think i'll have enough room to do that... Any help from anyone that has made a downpipe before? I'm making a downpipe, and welding a cat and 22" resonator on it before installing it on my car.

 

Thickness of the metal? What machine?

If the metal is 16 ga or so you shouldn't have a problem doing a butt joint. If you grind the edges and the metal is too thin you will just blow right through. The only reason you'd need to grind one or both of the pipes is if you weren't getting full penetration. On thinner metals you want to go as fast as possible while still getting good penetration. Too slow and the weld will blow through, too fast and it won't join the metals. The whole tack on top of tack thing is pointless. A mig weld is supposed to look like a mig weld, one continous smooth bead. Though you might need to do one stringer and then flip to the other side and do a stringer and do like four or five of them to weld the whole pipe.

If you can tig weld, learning to mig is like learning to walk when you run a marathon every other day.

 

Haha, ok, thanks for the tip. I've only Tig'd a few times, but I was pretty good at it so hopefully this goes smoothly. The metal is just those aluminized u bends from jc witney, 2.5 ID, I don't know about the thickness, but it is pretty thin. I guess I'll just do a small sample piece and make sure I'm getting full penitration. I'm not sure on the brand or model of the machine I'll be using, it is my cousins. Unfortunatly I will not have access to the TIG for a month or so, So i'm stuck with the MIG.

Thanks again for your input, it is much appreciated.

 

You will definitely get full penetration(or you should anyway). I usually weld them on either #2 or #3 on my HH140, depending on the joint. Sometimes on 3 it will burn through. That aluminized tubing is softer than regular steel of the same thickness.

 

Also make sure to get the tubing down to bare steel where you will be welding it. If you breath in the fumes of galvanized steel while welding it can make you throwup.

 

I thought alumanized steel can hurt your lungs not just make you throw up....anyone got a link about it?

 

alumanized and galvanized are tottally differant. I've never had a problem with welding alumanized at all. just make sure you grind it down to the bare steel before welding. the coating will contaminate the weld .

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by silly4lude &raquo;</TD></TR><TR><TD CLASS="quote">alumanized and galvanized are tottally differant. I've never had a problem with welding alumanized at all. just make sure you grind it down to the bare steel before welding. the coating will contaminate the weld . </TD></TR></TABLE>



If you ever put any flame/weld to galvanized make sure you go home and drink some milk. no bullshit.