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what flow quantity of gas when MiG welding?


daverclasper
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As usual, it depends!

A hotter weld, with more current, of thicker metal will need more gas.   If you're not in a still-air workshop, you will need more.   Anyway, I haven't got a flow meter, and my college machines (otherwise high-end) didn't either.   Enough was a gentle breeze on the cheek!

12L/m is a lot!  200mls a second, a litre every five!

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Normally alight hiss and breeze by the ear, or 7 if you have a flow meter. There are many variables and your test piece should tell you. If using tig with hf becarefull not to be earth, stings a bit by the ear!

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35 minutes ago, Colin Lindsay said:

So those little Halfords Argon / Co2 bottles will last about 5 minutes?

If your lucky, what a waste of money if you have a bit of welding to do!

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33 minutes ago, Badwolf said:

I wonder how long will it be before mig welding etc is banned by the snowflake brigade for releasing environmentally unacceptable gas (especially co2) into the atmosphere. Just a thought???

Got to take it out first, so could be neutral! We have to have air fed masks at work, due to the nasty fumes made by welding steel.  99.7 percent is stainless welding with tig at work.

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In answer to the original question, I use as little as I can get away with! As all the books/instuctors/YouTube videos will tell you, set your welder up on scrap metal before starting to weld proper. Wind the gas back until the weld starts to splutter. 

I find it quite surprising how little gas is required for car body panels in a draft free garage; literally a whisper of gas. 

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6 minutes ago, Peaks said:

In answer to the original question, I use as little as I can get away with! As all the books/instuctors/YouTube videos will tell you, set your welder up on scrap metal before starting to weld proper. 

I find it quite surprising how little gas is required for car body panels in a draft free garage; literally a whisper of gas. 

Yep, its only there to shield and stop the weld going porous 

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On 18/04/2021 at 20:53, Mathew said:

Got to take it out first, so could be neutral! We have to have air fed masks at work, due to the nasty fumes made by welding steel.  99.7 percent is stainless welding with tig at work.

Nasty fumes?  What nasty fumes?   Galvanised steel, yes!

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1 hour ago, JohnD said:

Nasty fumes?  What nasty fumes?   Galvanised steel, yes!

Your behind with the times, apparently normal welding with mild steal using mig can cause nasty fumes now. So even with welding tig on stainless they have got elf and safety in and we have to use air fed masks!

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42 minutes ago, Mathew said:

Your behind with the times, apparently normal welding with mild steal using mig can cause nasty fumes now. So even with welding tig on stainless they have got elf and safety in and we have to use air fed masks!

Stainless I can understand, some nasty stuff will be produced. Not enough to worry me once in a blue moon, but lang term it can't be good. Mild steel I am scratching my head, and CBA to research it.

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35 minutes ago, clive said:

Stainless I can understand, some nasty stuff will be produced. Not enough to worry me once in a blue moon, but lang term it can't be good. Mild steel I am scratching my head, and CBA to research it.

Apparently due to some dodgy research according to work! Although thay didn't use the term dodgy. Its another jump on before posible law suit reaction.

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13 minutes ago, chrishawley said:

As a baseline setting I use 7 - 10 lpm and adjust from there if special circumstances require.

Getting mine set up for a grown-up system on Thursday; a mate's been promising for years so ran into him today. I've to bring the Mig down to him and he'll supply gas cylinders, valves / regulators and anything else required. Now we're on the road!

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https://www.researchgate.net/profile/Lamia-Tallaa/publication/319401774_Carcinogenicity_of_welding_molybdenum_trioxide_and_indium_tin_oxide_View_project_SEE_PROFILE_SEE_PROFILE/links/5cb5b6104585156cd79b2558/Carcinogenicity-of-welding-molybdenum-trioxide-and-indium-tin-oxide-View-project-SEE-PROFILE-SEE-PROFILE.pdf

It's from the Lancet in 2017, and reports the findings of a group of epidemiolgists, at the International Agency for Research on Cancer.   They found an increased incidence of lung cancer in welders, world wide, that could not be explained by exposure to asbestos or smoking.   No figures given, no doubt they are in the many references cited, which I'm not going to pursue.

So yes, if you want a career in welding, get an air fed helmet!

John

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Several postings deleted to try and calm things down a bit.

Health and Safety wise,  "good" employers err on the cautious side and always want to keep risks ALARP, it's much cheaper in the long run than having to pay out millions in damages because someone has inhaled too much welding fumes.

I don't normally do much welding, but when I do (and I've actually done quite a bit in the last couple of weeks) I wear an FFP 3 respirator, and if I had an air fed mask I'd wear that.

If you want a demonstration, just blow your nose after an "unmasked" welding session and see how much dirt comes out in the snot - if that isn't enough to make you wear a respirator, nothing will.

Gas flow wise, I don't have a flow gauge, I just set the output pressure to give a flow that sounds right for the conditions, lower in the workshop and higher when outdoors on a windy day.

Using a CO2/Argon mix makes a huge difference to the weld quality, having used Hobbyweld 5 & 15, I'm not going back to pure CO2.

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Kevin, you deleted my reply to Mathew, in which I gave the reference to a Lancet article that explained why airfed masks are becoming the thing to have IF you are a pro welder.   That's a loss to the thread - please reinstate it!

And "heated"?   Mathew and I were in banter mode!   You might have asked if we were offended before moderating!

John

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I've always used 20% CO2/80% Argon when mig welding mild steel. BOC used to call it Argonshield 20, I think its called Specshield 20 now dunno why probably some marketing bright spark straight out of uni thought it sounded better! We tried 5% CO2 but 20% was better. 

Pure Argon for non ferrous. 

Practice makes perfect and grind off as much galvanising as possible or your eyes will go in different directions🥴. An enclosed filtered head set is the way to go and don't try welding in the wind, the shielding gas gets blown away. 

Iain 

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