Welding: Shielding gas options

[Paul]

I'm Looking for info re welding shielding gases.

Found the following so far:

http://www.mig-welding.co.uk/welding-gas.htm
http://www.mig-welding.co.uk/gas-composition.htm
http://shdesigns.org/Welding/gasmix.shtml
http://en.wikipedia.org/wiki/Gmaw

Does anyone have any other references, or local data?

[lachlan]

what info do you want exactly ?

your question is a bit like someone asking for info on cars ...

[Paul]

what info do you want exactly ?

Say for steel, ali and stainless, what's options are out there for welding gasses and which have what benefits/drawbacks/costs?

What would you use, given the choice and why?

What places can you get cylinders from (BOC/Supagas/etc)?  Would you go rental/customer-owned?  What sort of prices are people getting?

[PM]

Alloy - Argon
Stainless - Argon
Steel - Usually 12% CO2 / Ar mix, or 100% CO2

Grab your ankles at BOC, unless you use a significant volume (read 20+ 'G' size cylinders per year). Supagas and Air Liquide both sell industrial gasses.

[tim k]

depends what you want to weld, ali and stainless usually straight argon,
steel argon mix but can use co2, can work well with flux core but better if matched.
if you tell us what you have in mind then much easier to answer you question.

[Jeff B]

Ali- pure argon
Stainless- we use argon/co2 or sometimes argon/hydrogen
mild steel- argon/co2(argoshield)
Plastic-??
Thats for MIG welding, for tig welding we use pure argon for everything.

[Paul]

Cheers guys.

If you were to MIG steel with pure argon, what are the problems created, or why is this combo not good?

Is there much difference in results/strength/looks, with argomix vs CO2, when MIG'ing steel?  Apart from argon being 3 times the price of CO2.

[MRM]

Stainless- we use argon/co2 or sometimes argon/hydrogen

Would you use hydrogen? BOOM!

[MRM]

How much welding are you looking to do Paul?

Tradezone or one of those out east had little disposable cylinders for dabblers, 1 or 2 kg I think.
Apparently you can't buy cylinders any more, and renting them is the same cost per year whether you use 1kg or the whole cylinder.
The tradezone guy said they used to fill cylinders, but now they send them to BOC to fill, and on occasion they have just confiscated the customers cylinder for whatever reason. He has had to ring customers up and say "sorry, your cylinder is gone!"

[Paul]

Would you use hydrogen? BOOM!

I believe the argon/hydrogen and also the CO2, is classed as MAG welding (Metal Active Gas, vs Metal Inert Gas) - exactly the same gear, just different gas.  You can also get an Argon/Oxygen mix!  I think the active gasses are something to do with breaking up scale/rust/corrosion, or something, so the spark can get trough to the base metal.

[Paul]

How much welding are you looking to do Paul?

Tradezone or one of those out east had little disposable cylinders for dabblers, 1 or 2 kg I think.
Apparently you can't buy cylinders any more, and renting them is the same cost per year whether you use 1kg or the whole cylinder.
The tradezone guy said they used to fill cylinders, but now they send them to BOC to fill, and on occasion they have just confiscated the customers cylinder for whatever reason. He has had to ring customers up and say "sorry, your cylinder is gone!"

Probably not a lot.

Don't really want to want to be paying monthly rental on big cylinder.  I believe all of the 'old cylinders' that BOC handed out all those moons ago, were/are, still BOC owned, this was when BOC used to hand out cylinders and you paid for the gas only.  Due to tanks coming back many years/decades later, BOC's business model changed so there was also a monthly rental. So when people take these old cylinders back, they may well also be out of test date.  For some gas cylinders, it is the Law that if you present an out of date cylinder for fill, then it either has to be sent away for test (at your cost); crushed flat; or have all the thread reamed out of the neck (making it useless).  I guess there were some big safety issues with old cylinders, coming back with damaged tanks/valves and they want to sort this out.

Coming back to 'customer owned' cylinders, you CAN still get them - indeed there are multiple companies on trademe that sell them:
http://www.trademe.co.nz/Members/Listings.aspx?member=884430
http://www.trademe.co.nz/Members/Listings.aspx?member=1179440

They have a '10 year test' and I believe the 'breakeven' on the cylinder purchase, is about 2 years, vs renting one.  With some cylinders you can also get them retested after the 10 years is up, or dispose of them.  One of the downsides to 'customer owned' appears that getting them filled is not an instant thing - some need to be sent away and they are 'batch filled', so you may be without a cylinder for 2/3/4 weeks.  Wheras with rentals, it's almost like swap-a-bottle.  The LPG tank in my car is now on it's 7th year and I'll need to retest/replace that tank at/before 10 years is up (assuming I've still got the car!!).    Re-test is relatively simple process and is like a dive cylinder test.

[JR]

How much welding are you looking to do Paul?

Tradezone or one of those out east had little disposable cylinders for dabblers, 1 or 2 kg I think.
Apparently you can't buy cylinders any more, and renting them is the same cost per year whether you use 1kg or the whole cylinder.
The tradezone guy said they used to fill cylinders, but now they send them to BOC to fill, and on occasion they have just confiscated the customers cylinder for whatever reason. He has had to ring customers up and say "sorry, your cylinder is gone!"

I have even seen Co2 Sodastream gas bottles used on welders.... Bloody funny to see such a small bottle on a welder... Cheers JR

[Paul]

I have even seen Co2 Sodastream gas bottles used on welders.... Bloody funny to see such a small bottle on a welder... Cheers JR

I believe people have also used CO2 fire-extinguishers with an adaptor, on their welder (unscrew the 'spray nozzle', screw on adaptor, activate and clamp trigger!!).    And it's allegedly rather cheaper than welding suppliers and a bit easier to get refills..

[88V8UTE]

I have even seen Co2 Sodastream gas bottles used on welders.... Bloody funny to see such a small bottle on a welder... Cheers JR

  a very easy way of doing it!! when i was 18 i built up my Falcon speedway saloon using a cheap Mig and sodastream bottles, when i ran out i just shot down to the supermarket and swapped for some full ones, an added bonus is you dont need to worry about testing, i bought half a dozen REALLY old sodastream bottles off trademe, took them in to swap no worries , does work out a bit dearer than a big bottle, but if your not doing much welding its really convenient!!

[H2OSkier]

Here is the low down on Gases.

BOC trade names used are in New Zealand.

Mig (Mag) Steel - CO2 gives deep narrow penetration with a pronounced bead profile, produces alot of spatter, is slower, won't support spray transfer, but is relatively cheap.
Argoshield (Ar/CO2/O2) gives shallower, wider penetration with flatter bead profile, is low or almost spatter free, will support spray transfer, is faster, but more expensive.

100% Ar is not recommended for Mig of Steel or Stainless due to porosity, poor fusion, and large uncontrollable droplet size.

Mig of Stainless - Stainshield (He/Ar/CO2) gives clean fast weld with good penetration, flat bead, low spatter, no porosity. Can use Ar/CO2 which is cheaper.
DO NOT use any Argon/Oxygen mix with stainless.

Mig of Aluminium - 100% Argon, or Alushield (Ar/He) which gives much faster weld due to better energy transfer.

Tig - DO NOT use anything with Oxygen in the mix.
        Any CO2 can break down and release oxygen.       
for Steel use 100%Ar, or Ar/He mix
for Stainless, use 100% argon, or Ar/He mix, or for BEST results use Stainshield Tig (5%H2 in Ar) The hydrogen scavenges any oxygen that may be present, gives around 15% faster weld resulting in much reduced heat affected area and much less discolouration.

for Aluminium, use 100% Ar, or for BEST results use Ar/He mix - around 15% faster, less distortion, better(quicker) pool formation at start of weld. Downside is price and you use more.
DO NOT use anything with Hydrogen,Oxygen or CO2 for Aluminium.

These are all BOC trade names, but the other gas suppliers all do similar mixes.

Cylinders - Rental or owning is down to your situation and preference.
Rental rates vary considerably with BOC being the most expensive by far, and usuallly not prepared to negotiate.
If you don't have a choice in you location you will be stuck with renting their cylinder - they won't fill yours.
If you buy a cylinder, check that your gas supplier will fill them well into the future.
Owning is a good option if you have a static requirement with low, infrequent, consumption. check on the "Gas Price" for filling your cylinder compared with "Gas Price" for a rental - some suppliers charge more for filling your cylinder.

Does that help you Paul