?'s for the Welders...

[MikeDE]

I have some questions for the experienced Welders. Other than some arc welding I did a few years ago, I have little welding experience under my belt.

My first pertains to Gas, Argon and CO2, and their percentages. I plan to be welding SS and mild steel(MS), no cast iron or aluminum. I understand that an Argon/co2 mix is best for the SS/MS, while 100% argon is best for Aluminum. My local supplier has straight argon, and argon w/ 18% co2. I wanna know what's best for what I have to fix. I have some relatively thin SS exhaust piping and an M42 exhaust manifold that had a slight crack at the flange and the cyl 1 runner.

My second question is wire. I have a spool of 0.8mm non-shielded wire specifically for SS. Is this suitable for my needs.

And third, typically how much welding time does a given size container of gas give you?? I understand it also depends on the flow rate, but ballpark it.

If there is any other info anyone can offer, I would appreciate it. I see no reason why I should pay someone €100+ to fix this stuff. I figured 'F it, now is a good a time as any to get started'.

[shiboujin]

My local gas supplier said SS is best with a 90/10 argon to CO2 mix. But 18% CO2 will work for your small fix and most of your SS welding needs. 0.8mm should be fine as well. What you are doing is about what I've been working with for about a year. I don't think it's ideal but it works.

I usually manage about 2-3 full exhaust systems per medium sized tank with misc other stuff on the side. But again, it depends on a lot of factors.

[m73m95]

If you only need to make a few "stitch" repairs, the mix you have should be fine....Though the CO2 is high at 18% for SS, but pretty good for MS. I wouldn't weld anything SS that's going to be "structural", but filling holes/cracks should be alright. The wire is alright too.

Stainless is kind of a bitch to do, but not has hard as aluminum. Just make sure you stay behind the puddle, and "push" it rather than "pull" it.

Also, when welding any pipe, you should also purge the inside of the pipe with your gas mix. That way no oxygen can sneak in from the inside and ruin the integrity of the weld.

[jaywood]

I have a medium sized gas tank for my mig with 75/25. It lasts a very very long time. (not using it everyday) I'm getting 100% argon for my tig because it does most metals well.

[ThisGuy310]

It's not going to matter.
You are welding on thin SS tubing and it is going to get contaminated and lose its stainless properties when you don't back purge it.