Thread: CO2 Mig Gas For Steel Welding

AFAIK the gas would not be suitable for MIG welding....Ths stuff I use is an argon, CO2 mix..

My book mentions the gasses used for MIG welding are.

Argon, Helium and Carbon Dioxide..Also the book mentions Carbon dioxide must be welding grade that has had all the moisture removed..

hey why not give it a try and see how it welds .It feels good to follow your intuition and try something no one [or hardly anyone] has tried and if it works thats an added bonus.

As long as its not potentially explosive of course .Cant see them putting it in drinks if it was explosive ,people smoking etc

As you said, it contains nitrogen and that is the last thing you want to be introducing into your welds

Originally Posted by China

As you said, it contains nitrogen and that is the last thing you want to be introducing into your welds

Can you elaborate why?

Originally Posted by montiee

Can you elaborate why?

As I said in my first post, I can purchase a full 60kg bottle for $249 mine to keep at
http://cgi.ebay.com.au/Keg-Gas-Bottl...3%3A1|294%3A50
and swap the bottle for a full one for $49 at a home brew fill point. They say that their gas is pure Co2 food grade, but a couple of home brew forums that I have read say that the gas contains some nitrogen.

Would be great if the gas was pure, no rental costs and their system works like the barbee swap and go system. The bottles are tested every 10 years at no cost to you.
Someone out there must have tried or maybe is using this system for welding and would be interested to know if it works or not before buying a bottle.

Originally Posted by China

As you said, it contains nitrogen and that is the last thing you want to be introducing into your welds

Why is nitrogen bad for welds , what does it do ?? Isn't there a lot of nitrogen in in everywhere anyway? and isn't it inert more or less?

Originally Posted by Turpy

As I said in my first post,

Turpy, notice I wasn't quoting you when I asked the question. I was quoting the statement why nitrogen is bad for welds made by China. Usually when you quote a post and then comment after it the comment pertains to the quoted post which places it into context..

Often people just blurt out stuff saying something is "bad" just because it's not typical. Sometimes it might be but just stating it's bad doesn't mean much. Bad in what way? Nitrogen isn't explosive and mostly inert as far as I know so I'm puzzled about why it's bad. Perhaps he is confusing it with hydrogen.

Your idea is interesting and certainly given me something to think about should I even venture into mig welding with gas. ATM I make do with gasless but with mixed results (perhaps due to my inexperience though).

[quote=montiee;961307]Turpy, notice I wasn't quoting

Sorry Montiee, my mistake.

What I intend to do, is to go to a couple of gas fill points tomorrow and ask for a "Materials Safety Data" sheet.
This will have to list the gas ingredients.
I will also find out who supplies them the gas and then ring the supplier to find out if the moisture content is the same as whats in the Co2 welding bottles.

Originally Posted by Mathuranatha

Why is nitrogen bad for welds

Makes the weld brittle, and also if this gas has water vapour in it it will cause hydrogen embrittlement.

If you want disposable bottles use this http://www.bobthewelder.com.au/product.php?productid=101

however I believe these need to use a special regulator..

Nitrogen leads to porosity, see link for concentrations. http://www.netwelding.com/improving_start_quality.htm

As said above

OK so it makes the welds porous and brittle.So i guess it depends what Turpy is welding .If its just fixing rust in old cars or tacking a few shelf together or something that doesn't flex and porosity doesn't matter might save a bit of money /year with no bottle rental.

Originally Posted by Stringy

Nitrogen leads to porosity, see link for concentrations. http://www.netwelding.com/improving_start_quality.htm

If you have a look at Stringy's link, in a caption for a welding image it says: "0.12 % Nitrogen Sound Weld", this goes up to "some porosity" for 3.28 %.

I'm very interested now to know to level of nitrogen in the home brew supply. Surely for non-professionals this lack of 100% quality of the welds would not matter. Can you find out the percentage, Turpy? I think you might be on to something.

OK, some home brew outlets sell two types of gas which are pure CO2 the same as mig shielding gas, and also CO2/Nitrogen.

The outlet that I have been dealing with
http://www.liquorcraft.com.au/afawcs...CESSORIES.html
just sells plain CO2. Also it is cheaper to purchase the Australian Standard Approved Cylinders from their eBay website.
After a bit of research I found that Liquoraft refill the cylinders through United Fire Equipment in Moorabin Vic. The Material Data Safety sheet states that the gas used is just CO2. The chap I spoke to said that the gas is the same as mig shielding gas.
The bottles are not Aluminum, so they are heavy.

I don't use my mig a great deal, so I resent paying BOC a yearly rental. As for the small throw away bottles, very expensive for half an hour of welding, though I'll still use Argon when required.
Thanks for your comments.
Mario