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carbon steel headers

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carbon steel headers

Postby fab9racing » Fri Nov 10, 2017 12:05 pm

I am building a set of headers out of 18 ga carbon steel , when i butt weld the pieces,i can get them to weld up ok , however i have used a pipe ex pander on 1 end of the pipe so that i can slip them in and then tig them up , the problem i am running into is when i start my run it goes pretty good on the pipe when it approaches the stretched pipe it just peels it back and i can chase if fast enough to catch it , any ideas what i am doing wrong would help
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Re: carbon steel headers

Postby noddybrian » Fri Nov 10, 2017 2:39 pm

Welcome to the forum Fab9racing.

I would say the likely causes are torch angle - you need to direct the heat at the inner piece & only " wick " the heat toward the edge of the outer - not getting the filler rod in quickly enough to bridge the joint or too thick a filler & possibly reluctance of the puddle to bridge if there is any contamination from the expander rollers - there are guys here that do plenty of header work who hopefully will chime in with possibly more insight than I have as I don't do much of this type work.
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Re: carbon steel headers

Postby Oscar » Fri Nov 10, 2017 9:08 pm

18ga is what, 0.050"? That's very thin to begin with as most headers are 16ga, 0.0625" material. The part that underwent expansion is now, depending on the expansion, 0.035-0.045" or so? That's VERY thin and leaves no margin for error. Torch angle, arc length, have to be correct and tight, respectively. Amperage has to be spot on; pulse might help if you have practice pieces, which I hope is what you're already practicing on. Filler rod also has to be the correct size. You will not be able to easily do this with 1/16" filler. Try ordering 0.030-0.035" filler, with a max of 0.045". Right now Amazon has really good pricing on INE wire in that range in the 10lb pack. Weldingsupply.com has it by the pound (their house brand) at really good prices as well.

If you're TIG'ing like this:
Image

...you're doing it wrong, with regards to arc length. You need to be like this:
Image


That's a 1/16" tungsten by the way, so you can use your mind's eye as to how close you need to be. Otherwise, that's why you're trying to chase the curling edge. Don't start the arc on the other pipe then try to run into the expanded one. You need to use a tight arc and get the miniature lap joint to fuse right from the start. You also can't have any gap, since at this size regime, any visible gap is considered to be huge if you can see it. I've only done this a handful of times in the past, but as you can imagine, I struggled with the same thing you did, until I discovered what works for me. Note that my actual torch angle in the pics is wrong, I am merely trying to depict arc length. The actual torch angle is more like 12-20° off the vertical, not much different from doing a standard butt-joint weld.
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Re: carbon steel headers

Postby fab9racing » Mon Nov 13, 2017 2:56 pm

Everything you said was spot on , just wish i would have seen this friday , Trial and error finally got me close and gap was the most critical thing , i ended up using the pulse feature with a 36a max and gas around 8c , used the wire from my mig for filler , i will order me some small filler this week and hammer on it again , thanks for the input .
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Re: carbon steel headers

Postby mpete53 » Tue Nov 14, 2017 11:48 am

On light material I find that I like to use the smallest tungsten I can for the amperage. The smaller tungsten seems to me to lights up better, gives a more directed arc which is easer to control and are much quicker to sharpen.
Most of my welding is on thin material so I mostly use .040 and 1/16 tungsten. The photo is of a .025 wall tube from an old Ikea deck lamp done with a .040 tungsten and .023 mig wire.
There seems to be a trend here to try and do every weld with the same size tungsten, why I don't understand. Changing tungsten sizes in the torch takes only a minute and I fine using the smaller size tungsten makes thing work so much better. I use old medicine bottles' to hold one of each size gas lens and its collet with the top marked in sharpie with the size. I find this make changing size a snap
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Re: carbon steel headers

Postby LtBadd » Tue Nov 14, 2017 6:38 pm

mpete53 wrote:On light material I find that I like to use the smallest tungsten I can for the amperage. The smaller tungsten seems to me to lights up better, gives a more directed arc which is easer to control and are much quicker to sharpen.
Most of my welding is on thin material so I mostly use .040 and 1/16 tungsten. The photo is of a .025 wall tube from an old Ikea deck lamp done with a .040 tungsten and .023 mig wire.
There seems to be a trend here to try and do every weld with the same size tungsten, why I don't understand. Changing tungsten sizes in the torch takes only a minute and I fine using the smaller size tungsten makes thing work so much better. I use old medicine bottles' to hold one of each size gas lens and its collet with the top marked in sharpie with the size. I find this make changing size a snap

Good job mPete, I do agree with what you said about tungsten size, depending on what's being welded. There's a time and place when you could do a weld with 3/32" but 1/16 or .040 can be an advantage, bottom line is the weld got done correctly and we all have different ways to get to the same place
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