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  1. #1
    Join Date
    Sep 2009
    Location
    Gatton, QLD
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    34

    Default Double banger - Duragal removal and breathing mask for welding

    I'm a hobby welder. Most of my welding is Duragal RHS, I want to remove the duragal coating in the area to be welded because of weldability (is that a word?) and toxic fume issues.

    I know that I can flap wheel or grind the outside of the RHS to remove the duragal coating, but the duragal coating remains on the inside and will cause toxic fumes. I know that duragal vendors state 'duragal CAN be welded without removing the coating'. But health-wise, SHOULD it be welded without removing the coating?

    I've tried soaking the RHS stubs in white vinegar, I couldn't tell if it helped or not. Any thoughts on other methods to remove the duragal coating?

    What breathing mask (to wear under welding hood/mask) is recommended? I sometimes use a fan, but still concerned with breathing welding fumes from both duragal and non-duragal material. Obviously would need to fit under welding mask and be effective for welding.

    Thanks for the help.

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  3. #2
    Join Date
    Feb 2006
    Location
    Perth
    Posts
    27,757

    Default

    Masks are horrible to wear full stop but even more so under a welding mask.

    I set up an small exhaust hood and decent size squirrel cage fan and it is one of the best t things I ever did setting my shed.
    It took me a while to make but it works way better than I expected. I even do some chemistry under it when I'm working with nasty chemicals.

    Not just galv fumes but welding fumes, plasma cutter fumes, spay paint fumes, grinder dust, farts and BO - what more do you want?
    The vice is removable - it's mounted on a post that fits in a socket and just lifts out

    Squirrel cage Venting fans-img_3880-jpg


    One problem I have is the shed ceiling slopes the wrong way so if I weld outside the hood some fumes rise and creep up up along the ceiling and are not collected by the hood/fan.
    This eventually fills the shed with fumes and grey goo settles on everything. To fix this I added another exhaust fan at the other (higher end) of the shed.

  4. #3
    Join Date
    Feb 2010
    Location
    Ballina, NSW
    Posts
    725

    Default

    You might want to be more specific about how you're welding it too. Have a look at the recent thread about tig welding gal as well as other older threads too. If you're stick welding just set up a fan and blow the smoke out the door. If you've got your face right down in the haze doing long tig welds - well then you've got other things to consider.

    Removing zinc - we'll the grinder/flap wheel is the way I'd go, but hydrochloric (muriatic) acid definitely gets it off. You can get that easy from bunning's in the bricky's section. Swimming pool acid is the same. I don't use it for fear of promoting long-term rusting on the inside of any box sections. Some people don't think this is an issue. Rinse well. Don't forget eye protection as big chunks of zinc can fizz and spit acid. If you're grinding, look for a change in spark colouration pattern - which indicates you've ground through the zinc and have actually reached steel. Duragal zinc is very thin, but it still takes more than a wipe with the grinder to get rid of it.

    In terms of masks, I got some of these from the big bunny. They don't have them on their web site, but my local store stock them.
    http://solutions.3m.com.au/wps/porta...+8705822&rt=r3
    There are non disposable half mask versions as well, but for hobby work then I reckon the disposables are pretty good. They seem to fit well when I use them.

    Personally, a heavy flap disk and some good ventilation are the go to methods for me.

    Cheers

    - Mick

  5. #4
    Join Date
    Sep 2008
    Location
    Perth
    Posts
    363

    Default

    I wear a 3M 7551 mask for painting. Obviously it would never fit under a welding hood.

    As per the other thread, I tig duragal all the time just flap wheeling the outside. No issues with fumes whatsoever.

    When I used to stick weld it, I wouldn't flap wheel at all. I'd hold my breath for short runs and/or use a fan.

    All my welding is outside. It would be different in a confined area. But outside zinc smoke is quite dense and easy to avoid. And I get no smoke at all by cleaning just the outside.

  6. #5
    Join Date
    Jan 2004
    Location
    Mackay Qld
    Posts
    3,466

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    Individuals react in very different ways to zinc fume inhalation.Factors such as age, pulmonary health, frequency of welding and the environment that they weld in,will dictate the degree of precautions they should take.

    Those with poor lung capacity or asthmatics should steer clear of inhaling welding fumes in general.

    The simple step of placing a fan gently blowing from behind is a pretty good one for stick welders.

    Grahame

  7. #6
    Join Date
    Sep 2010
    Location
    Lebrina
    Posts
    1,099

    Default

    Quote Originally Posted by Grahame Collins View Post
    Individuals react in very different ways to zinc fume inhalation.Factors such as age, pulmonary health, frequency of welding and the environment that they weld in,will dictate the degree of precautions they should take.

    Those with poor lung capacity or asthmatics should steer clear of inhaling welding fumes in general.

    The simple step of placing a fan gently blowing from behind is a pretty good one for stick welders.

    Grahame
    Totally agree, in fact, the fan blowing from behind works very well when mig welding too. All you are looking for is to have a light breeze that at least holds the Zinc fumes in front and away from your breathing zone. I have personally used such a fan when welding Duragal frames in a production of 1500 odd units in a workshop environment and experienced no porosity and no ill effects.
    Once you have had a proper dose of metal fume fever, you will never want another and will improvise where possible or wear a respirator in order to avoid it. That I promise.
    Duragal is not as big an issue as proper galvanising.

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