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19th Aug 2018, 03:53 PM #1Senior Member
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Help/advice welding galvanised steelthis mamange
Hi everyone,
i have several off cuts of 150 X 50 X 3 RHS that's rolled galvanised, enough to make up some workshop benches.
ive heard bad things about welding galvanised steel, so I'm seeking some guidance.
I guess I can weld it outside for a starter, but is there any mask I can use to protect me from the fumes, and if so what?
i only have a stick welder.
i believe it 'spatters' too?
is this manageable or should I dump it and buy some more with just red oxide undercoat?
Ps I hate dumping steel.
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19th Aug 2018, 03:54 PM #2Senior Member
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And as you can see from the title----I can't type either
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19th Aug 2018, 03:59 PM #3Senior Member
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Is it hot dipped gal or dura gal?
Regards
Bradford
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19th Aug 2018, 04:22 PM #4Most Valued Member
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As far as I know there is no "cheap" mask for welding, they are available but with a very healthy price tag, mainly used for welding titanium and so forth. I weld a lot of Galv both hot dipped and duragal, it's a messy dirty occuption.
What I'd do is to grind away the plating, using a flap disc or grinding wheel, till you see sparks coming off the area to be welded. Then it can be welded OK, if you find that you're still getting fumes, you could set up a portable fan to blow them away.
Hope this helps,
KrynTo grow old is mandatory, growing up is optional.
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19th Aug 2018, 05:01 PM #5Member: Blue and white apron brigade
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It's manageable if the welding takes place outside and use a fan to blow the fumes away.
However, I would recommend grinding the Zn anyway otherwise unless you have considerable skill you simply won't get as good a weld if you leave the Zn coating on the steel.
The grinding/ sanding removal should extend at least 25 mm either side of the weld line otherwise the heat from the weld will still generate ZnO fumes from the nearby Zn.
Beware that if the SHS is galvanised internally you won't be able to grind that away so there will still be some fumes.
The ZnO fumes generated are mostly less than one micron in size so if you decided to work indoors and use a mask you should use a P3 type filter cartridge in a tight fitting mask. Remember You have to leave the mask on for some 10s of minutes after the welding as the fine dust hangs around in the air at levels you cannot see but can still affect your respiratory tract.
Most folks don't realize that welding ungalvanized steel produces a heap of fine dust which is just as bad for you long term as the ZnO fumes. Because I find masks a right PITA to wear when welding I set myself up an area in my shed when I can weld without a mask . Its just a ventilated booth with high air flow and I can even weld galv directly without being affected but I still usually removed the galv where I can for the reasons described above.
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19th Aug 2018, 08:06 PM #6Senior Member
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Thanks everyone for the good imput .
the finish is duragal not hot dipped.
Im comfortable to follow your suggestions and get a mask and weld outside with a stiff wind
thank you all seriously---thanks
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19th Aug 2018, 08:28 PM #7
Brian, One last recommendation, milk ! Drinking milk helps to neutralise some of the toxins that you will inhale. If you start to get a headache, pack it in for a while.
Best Regards:
Baron J.
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19th Aug 2018, 08:54 PM #8Banned
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Since it's just Duragal, there shouldn't be a problem it will just burn off. Once. Finished just spray the joints with cold gal and it should look OK!
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20th Aug 2018, 09:16 AM #9Senior Member
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good suggestion BaronJ and onanon. I was intending spraying them grey anyway. Im replacing a bench I have made do with since my dad gave it to me when he shifted house in the 70's. I think he inherited it from an uncle. Since Im now in my 70's I figured I could relegate it to the new 'storage room' and get the work room looking more like a 'real one'
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20th Aug 2018, 10:28 AM #10Senior Member
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woven ceramic discs work well for galv removal too, with minimal steel removal. The pic shows three layers; the coated surface, breaking in to the galv layer, the raw steel underneath. This on 150x50x2mm RHS.
Not all pads are created equal, Nortons don't last at all, did one face of both ends of x14 lengths of galv RHS on the weekend, disc was finished.
Basic, but have the rotation direction heading off the edge, rather than into any edge; discs last longer.
1_woven_disc.jpg 2_galv_removal.jpg
I came across this on the weekend:
http://www.sperkoengineering.com/htm...Galvanized.pdf
attached below
extract: "
- Typical “metal fume fever” begins about 4 hours after exposure, and full recovery occurs within 48 hours."
It does list suitable disposable masks: 3M 9920, 9925, 9970
I worked in a family Sheet Metal business many years ago (70's), so galv fumes were ever present. Milk was the 'cure all' back then too. No masks of course.
Hadn't ever occurred to me to aim for a minimum clear width as BobL suggested, there is logic in that. Just found this from 2009 Maerican galvanisers Association,
Preparation of Weld Area
AWS D-19.0, Welding Zinc Coated Steel, calls for welds to be made on steel free of zinc in the area to be welded. Thus, for galvanized structural components of a fabrication, the zinc coating should be removed at least one to four inches (2.5-10 cm) from either side of the intended weld zone and on both sides of the workpiece. Grinding back the zinc coating is the preferred and most common method; burning the zinc away or pushing back the molten zinc from the weld area can also be used.
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20th Aug 2018, 11:10 AM #11Senior Member
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Duragal is not so bad, I weld a lot of it and all I do is grind it back as stated above.
I use a flap disc and do all my welding outdoors, never used a mask and never had a problem.Regards
Bradford
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20th Aug 2018, 11:38 AM #12Senior Member
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thanks Node and Bradford. Some good reading there and Im never too old to learn something.
Ive welded duragal in the past outside and never had a problem, but Ive seen references to it being a problem and figured my lungs are nearing their used by date, after years of industrial exposure , before anyone knew about safety. So I've been trying to be more careful these days.
Thanks again everyone for your prompt and useful help.
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20th Aug 2018, 12:03 PM #13Banned
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I've been welding daragul for for for for yearsssss and never had a problem. The one lung I have left hasnsssssn't oooobjected/
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20th Aug 2018, 05:16 PM #14Member: Blue and white apron brigade
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Just to be clear about this, ZnO fumes will not actually kill you. ZnO fumes are major pulmonary irritant that can lead to debilitating high fever like symptoms often a few hours after exposure, but it eventually goes away within 48 hours and there are no know long term effects of high ZnO exposure. In terms of injection Australian grown (especially WA) food is Zn deficient and so we can all use a bit more Zinc in our diet. The same cannot be said for other metal dusts and dust in general is considered the 5th leading cause of all deaths world wide.
Some more info here
https://www.lincolnelectric.com/asse...ta/FACT-25.pdf
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20th Aug 2018, 10:11 PM #15Golden Member
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I poisoned myself welding gal once, the symptoms were identical to the symptoms I get when in the early stage of catching the flu, right when it hits you like a ton of bricks.
I remember thinking at the time "how the hell did I catch the flu..? I'm in the shed and haven't been around anybody else" shortly followed by "oh.. bugger, I know what's going on, time to put the welder down, go inside and drink some milk and take some calcium ascorbate" haha.
I was back to normal in a few hours.
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