What I mean is, If I want to make sure I am getting no leaks from my intercooler pipes, would it hurt to weld the pipe together then run a bead over that? I do V the pipes ends now.

Using a MIG.

 

Not sure what you mean tbh. Do you mean can you put a tack where the pipes join, then weld over the tacks, and then put another run over that?

You dont want to put any tacks where you are going to weld if you can help it as it wont have penetrated properly so is likely to crack or leak when you weld over it. Try using a scrap bit of angle and a couple of hose clips to hold the pipe together. Or at least weld a section of the pipe that has no tack in it and then grind the tack out

 

Ok, I got ya. I was talking about taking it all the way around, But I guess that would be a bad idea.

 

Why cant you just fully weld it? is it really thin stuff your using?

 

No, it's 16G. I was just thinking of ways to make sure I get no leaks at all.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CBURKE &raquo;</TD></TR><TR><TD CLASS="quote">I was just thinking of ways to make sure I get no leaks at all.</TD></TR></TABLE>
just make sur you get purfect beads all way arounhd the pipe

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybrid2007 &raquo;</TD></TR><TR><TD CLASS="quote">You dont want to put any tacks where you are going to weld if you can help it as it wont have penetrated properly so is likely to crack or leak when you weld over it. Try using a scrap bit of angle and a couple of hose clips to hold the pipe together. Or at least weld a section of the pipe that has no tack in it and then grind the tack out</TD></TR></TABLE>

all of this is completely incorrect info. you can certainly weld over tack welds, and your welds will be perfectly sound if you weld correctly.

 

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

all of this is completely incorrect info. you can certainly weld over tack welds, and your welds will be perfectly sound if you weld correctly.</TD></TR></TABLE>


thats what i was taught

 

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

all of this is completely incorrect info. you can certainly weld over tack welds, and your welds will be perfectly sound if you weld correctly.</TD></TR></TABLE>

IMO its bad practice to do this. Yea you might not come across problems with light guage pipe, but when you build something structural its not a good idea to just weld over your tacks.

Not looking for a fight just getting my point across

 

thats fine, well ive read 3 welding books and ive never heard something that absurd. thats the only way to get the tubes held in place 100% right. tack welds also limit the amount of distortion the final piece will have. you need to make a lot of tacks, then weld over them, they melt and become part of the weld. with proper heat, theres no way they wont penetrate properly when welded over. and theres really no way they would crack either. if you clean, tack, and let the postflow work there will be almost zero contamination.

grinding out the tack is really bad practice as well. this will surely contaminate your bead, especially with aluminum.

so im not trying to argue either, but your point is not really very valid so far as my research or experience shows.

also if you were to hold things together by tacking a plate across the joint then this would also be bad because you would be messing with the crystal matrix of the metal, making it discontinuous somewhere it doesnt need to be when welding happens(HAZ is obviously somewhere it has to happen) so please dont do this either.

 

Ok, so I can tack weld the pipe together then go over it with a full bead?

Like I said, I just want every pipe air tight!!!

 

yes. you will be disappointed if you dont tack your workpieces first. On a regular tube, i give it 4 tacks, evenly spaced. On a collector i give them 4 tacks when buidling it in halves, 3 on the big side, one on the short inside side.

If you dont do this the end you are not welding will open or close depending on fitment.

 

agreed. I tack wel 4-5 times on maifold material to ensure its all in place and tight. I used to tack 2-3 times and on the final weld, that damn runner was completely distorted and would fit the jig! learners mistakes!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dfoxengr &raquo;</TD></TR><TR><TD CLASS="quote">thats fine, well ive read 3 welding books and ive never heard something that absurd. thats the only way to get the tubes held in place 100% right. tack welds also limit the amount of distortion the final piece will have. you need to make a lot of tacks, then weld over them, they melt and become part of the weld. with proper heat, theres no way they wont penetrate properly when welded over. and theres really no way they would crack either. if you clean, tack, and let the postflow work there will be almost zero contamination.

grinding out the tack is really bad practice as well. this will surely contaminate your bead, especially with aluminum.

so im not trying to argue either, but your point is not really very valid so far as my research or experience shows.

also if you were to hold things together by tacking a plate across the joint then this would also be bad because you would be messing with the crystal matrix of the metal, making it discontinuous somewhere it doesnt need to be when welding happens(HAZ is obviously somewhere it has to happen) so please dont do this either.</TD></TR></TABLE>

Ok i see your point, and i've realised taking techniques from what i do and expecting them to be the same in this sort of stuff is pretty stupid now i think about it.

From the pipe work i've done, i still wouldnt weld over tacks when using MIG but thats just me. TIG on the other hand, i wouldnt worry about it

Down at work we get a royal bollocking for tacking in weld areas unless its totally nessecary, but everything has to be tested and inspected so its a little different.

So if you were welding up Alu pipe with MIG you wouldnt even grind out the starts of your weld to weld into them?

 

I think everyone may be missunderstading what I am saying.

I don't me tacking them so I can make sure they stay, I mean like run a tack bead all the way around it so it's like TIG welding it, then running a full bead like a MIG does.

 

Why would you want to do this?

 

To be 100% sure it is air tight. This is for charge pipes. I know it's easy when tiging them.

 

Mig welding it one run should be more then sufficient. As long its a clean and welded properly. Running two beads will make it THICK as hell. Not necessary.

Unless your welding something REALLY thick. Then beveling and welding it multiple pass would be the correct way.

 

Ok thats what I wanted to know.

 

when he says THICK he means wall thickness of 0.25"+ Something like 16 guage (0.0598") tubing is pretty thin and definitely only requires 1 pass.

As far as your terminology, tack welding is joining metals together at a single point. A root pass is the first pass of a multi pass weld. The root pass provides the penetration and any further passes are primarily to fill the remaining area of the V groove

 

Thank you, that helped..........

 

yes, just weld it once, and then check for leaks.
i do sometimes use a similar technique of a full weld being multiple tack welds however, with my mig. I only use it fot non structure of course, and it is only to make a better appearance with MIG. it does end up looking like TIG welds with a large electrode and filler, which is the point of it. Again for non-structure only.

Process involves fitting the pieces with a few regular tack welds, then run a bead almost as fast as you normally would, but you press and release the trigger a lot during that time, so you basically have a bunch of tacks on top of eachother like the coin effect. you should try that sometime for something non-structural that you would like to have a little better appearance.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CBURKE &raquo;</TD></TR><TR><TD CLASS="quote">I think everyone may be missunderstading what I am saying.

I don't me tacking them so I can make sure they stay, I mean like run a tack bead all the way around it so it's like TIG welding it, then running a full bead like a MIG does.</TD></TR></TABLE>

If you're talking about tacking over and over again until you get all the way around, and then going over it again steadily, don't do it. You'll end up with way too much material and it will be obvious it was done by a rookie. It is possible to do a series of "tacks" that look like a good bead, like the previous poster wrote, but that's not how it's normally done, and for good reason. It's a lot slower and not as good. I'm currently somewhat out of practice migging that type of material, but it's not that hard, you just need to get the right settings and movement. If you set your wirespeed and arc voltage (or amperage, if you have a constant current machine) correctly and have a steady hand, you will be able to make a nice weld around the entire tube in one steady pass. (Although in reality you'd probably move the tube a couple times to get at it)

However you do this, be sure to accomodate the movement of your motor with some flex sections somewhere..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dfoxengr &raquo;</TD></TR><TR><TD CLASS="quote">
Process involves fitting the pieces with a few regular tack welds, then run a bead almost as fast as you normally would, but you press and release the trigger a lot during that time, so you basically have a bunch of tacks on top of eachother like the coin effect. you should try that sometime for something non-structural that you would like to have a little better appearance.</TD></TR></TABLE>

That is what I was talking about.

 

yeah if you get good at it then you can do it and itll seal. will work alright for exhausts so long as theyre supported well when installed. but be careful youre not trying to use this method to make structural things.
and you dont need to weld over it.