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Thread: Cutting torch pops on shut down

  1. #1
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    Cutting torch pops on shut down

    Hey everyone. I'm getting started with oxy acetylene welding. I bought some used Victor gauges and torches, but upgraded the main torch handle to a new Victor H315FC so I would have flashback arrestors. The cutting attachment is a CA2460 with a #2 tip.

    Everything is working fine when I'm cutting, but when I shut the torch down it always pops. I am shutting the oxygen off first and then the acetylene. From what I've read, shutting the acetylene off first is usually what causes popping. So what am I doing wrong?

    I thought the tip might be dirty, so I removed it cleaned the holes, but it still popped when I shut down.

    Any suggestions would be appreciated.

    Thanks.

  2. #2
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    Re: Cutting torch pops on shut down

    I shut down acetylene first myself. The main cause for popping is generally a poor seal somewhere that introduces outside air into the system. Least likely is hose to torch connection. Second most is where cutting head attaches to mixing body. Third would be leaks at the valves to adjust your gas. Most likely is the seat of the cutting tip. Sometimes just loosening the nut, rotating the tip and retightening the tip will correct that. Sometimes a new tip is needed, worse case would be the seat in the cutting head needs to be refaced.

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  4. #3
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    Re: Cutting torch pops on shut down

    As MJD said, probably the tip to torch seal. Try loosening the nut and rotating the tip a couple of times while pushing in on the tip. Sometimes if it's only a minor leak that'll fix it but burnishing the seat.............Mike

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    Re: Cutting torch pops on shut down

    Thanks for the quick replies. I'll try your suggestions and let you know how it goes.

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    Re: Cutting torch pops on shut down

    Here's a dedicated thread to using a cutting torch that maybe helpful.

    https://weldingweb.com/vbb/threads/6...-cutting-torch

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    Re: Cutting torch pops on shut down

    Quote Originally Posted by BD1 View Post
    Here's a dedicated thread to using a cutting torch that maybe helpful.

    https://weldingweb.com/vbb/threads/6...-cutting-torch
    Thanks for that link. I did see that while searching for answers about torches popping. I'll definitely look at it more later.

    I tried rotating the tip a couple of times while pushing in on it and tightening the nut, but it still popped when I shut it down. I have a 00 tip that looks new and unused, so I tried that tip and it popped too. I also have a CA1060 cutting attachment, so I'll guess I'll try that next and see what happens.

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    Re: Cutting torch pops on shut down

    I have always shut down acetylene first for 40 years plus and never had a pop. I have 2 older torch manuals from the 80's (Victor and Purox) that showed that as SOP, explanation was that would blow out the flame and purge the torch passages of acet.
    I doubt there is anything wrong with your torch, the pop is from acetylene burning back into the torch and leaning out as it burns off.

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    Re: Cutting torch pops on shut down

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    Re: Cutting torch pops on shut down

    I've always turned off the gases in the reverse order that I turned them on -- acetylene on, oxygen on, oxygen off, acetylene off -- and if the torch ever popped, it was always because the nozzle or cutting attachment wasn't tight enough. Sometimes I'll hold the torch handle in my hand and tighten the nozzle with a wrench (rather than just hand-tightening it) and that stops the popping. If you have an old rig, check the o-rings for dirt or nicks.

  12. #11
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    Re: Cutting torch pops on shut down

    Is it possible that the oxygen valve isn’t closing up
    tight ,creating a sort of a “fuel turned off first” pop
    situation?
    Miller a/c-d/c Thunderbolt XL
    Millermatic 180
    Purox O/A
    Smith Littletorch O/A
    Hobart Champion Elite

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    Re: Cutting torch pops on shut down

    Quote Originally Posted by jpump5 View Post
    Is it possible that the oxygen valve isn’t closing up
    tight ,creating a sort of a “fuel turned off first” pop
    situation?
    That was it. Before I changed the cutting attachment I tried shutting off the torch fuel valve and the oxygen preheat valve. Then I held the tip close to my ear and I could hear a faint hissing. When I closed the oxygen valve on the torch handle the hissing stopped. So a bit of oxygen was leaking past the preheat valve even if I closed it tightly.

    So I swapped the 2460 attachment for the 1060 and everything seems fine. No pop when I shut it down. Thanks for all the advice.
    Last edited by streetcore; 04-26-2021 at 02:55 PM.

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    Re: Cutting torch pops on shut down

    You should also be aware of tip cooling.

    If you run a heating tip too close to the steel, or in a confined space, the gas flow won't adequately cool the tip, and you'll get one Heck of a POP. The tip is cooled by gas flow. Restrict that flow by not having adequate free space beyond the tip,, and ya gots troubles. Don't want heat backing up into the tip.

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    Re: Cutting torch pops on shut down

    Quote Originally Posted by farmersammm View Post
    You should also be aware of tip cooling.

    If you run a heating tip too close to the steel, or in a confined space, the gas flow won't adequately cool the tip, and you'll get one Heck of a POP. The tip is cooled by gas flow. Restrict that flow by not having adequate free space beyond the tip,, and ya gots troubles. Don't want heat backing up into the tip.
    Thanks Samm. Is that what causes popping when using a cutting torch head? I was having that happen, and a friend who's a pro welder told me to turn up the oxygen pressure / flow (quite a bit higher than the manual said), and the popping stopped. I guess the cutting torch tip was getting too hot? (It seemed to happen when I got too close to the workpiece, which suggests the heat was coming back into the torch tip...)

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    Re: Cutting torch pops on shut down

    Quote Originally Posted by 12V71 View Post
    I have always shut down acetylene first for 40 years plus and never had a pop. I have 2 older torch manuals from the 80's (Victor and Purox) that showed that as SOP, explanation was that would blow out the flame and purge the torch passages of acet.
    I doubt there is anything wrong with your torch, the pop is from acetylene burning back into the torch and leaning out as it burns off.
    This.

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    Re: Cutting torch pops on shut down

    To lean of mix add a little fuel gas.
    It can also tip to close to the steel

    Dave

    Quote Originally Posted by streetcore View Post
    Hey everyone. I'm getting started with oxy acetylene welding. I bought some used Victor gauges and torches, but upgraded the main torch handle to a new Victor H315FC so I would have flashback arrestors. The cutting attachment is a CA2460 with a #2 tip.

    Everything is working fine when I'm cutting, but when I shut the torch down it always pops. I am shutting the oxygen off first and then the acetylene. From what I've read, shutting the acetylene off first is usually what causes popping. So what am I doing wrong?

    I thought the tip might be dirty, so I removed it cleaned the holes, but it still popped when I shut down.

    Any suggestions would be appreciated.

    Thanks.

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