Welding Tips and Tricks

Hey Folks,

I know that this question probably been kick around forever and I have done three searches on this site's archives, but I'll ask anyway.

I've just switched from MIG to GTAW. With MIG I would burn my 75/25 bottle down to about 100psi. Now that I have gone to Argon I want to know if 100psi is OK with this gas?

Sorry to resurrect a tired old issue.......

Thanks

It all depends on the filling practices of your supplier. Some people have bad luck with moisture in the bottle when it is close to being empty. Others don't. The only way to know is to try it.

Oscar wrote:It all depends on the filling practices of your supplier. Some people have bad luck with moisture in the bottle when it is close to being empty. Others don't. The only way to know is to try it.

Oscar,

Being on the vertical learning curve with TIG I am trying to rule out things that may become issues in the background. Whew, this medium is a real 'event' every time I light an arc, but I'm getting there.

I understand you reply and I thank you...!

Go until you get porosity. Just make sure it's not on a Sunday or after hours.

weldin mike 27 wrote:Go until you get porosity. Just make sure it's not on a Sunday or after hours.

That is what I did with my MIG gas or until I got really nervous. I guess it's okay to push it 'cause I'm not doing anything that is structural or life threatening.

Thanks for the input.......

That's it. If you are concerned, just do some practice with the last little bit.

Different gas suppliers have different policies, and it might even have to do with the local environment. Maybe if it's humid where you live, there's a greater risk of moisture contamination in bottles that are drawn all the way down to 0 PSI. When my bottle got down to 200 PSI I called them and asked if they had a minimum. They said nope, they don't care. Just to be a good citizen/customer, I brought it in when it got to 100 PSI. True to their word, they didn't check at all when I came in with it. Just brought out a full cylinder and took my money.

Aren't you doing yourself out of money by not using everything up?

weldin mike 27 wrote:Aren't you doing yourself out of money by not using everything up?

Yes, if your supplier sets no minimum return pressure, you're not using a little of the gas you paid for and could have used. My bottle came with 2200 PSI and I returned it with 100 PSI, so I "wasted" less than 1/20 of the gas they sold me. Ideal gas law and all that. A little more than $2.00 lost, if I could have operated the regulator/flow meter down to 0 PSI. The regulators often operate at 50 PSI though, so I imagine when the tank pressure gets near that I'd begin to have problems. So maybe $1.00 of gas wasted?

Worth consideration.

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An ounce of prevention is better than a pound of cure.

I'd never considered that. Always seem to run out completely.

I think the biggest factor is who fills the cylinders - if your using small hobby sizes that you own & some local outfit is filling them probably with a gas over air pump from a few full size cylinders manifolded together expect moisture / contamination / bad gas / wrongly labelled gas etc - if you live somewhere like I do then about the only gas option is BOC or Air Products - either way you will have to rent the cylinders & get ass raped for filling but on the up side I have never had or even heard of anyone getting bad gas & have always completely emptied cylinders to the last PSI - no problems.

Boc seems to have the same modus operandi all over the world. They are losing out to swap and go cylinders here in Australia, so that's a good thing.

Very few places around me in the us will even give you back your own cylinders. If they do the turnaround time is often weeks, not minutes. And they charge more to get you back your own tank.

I have been dealing with a local weld shop for my gas (tig and mig) and I get a "new" tank each visit. I would exchange tanks about 50 psi (indicated) on my gauge. I don't have anything pressing right now so I will see what happens when drain the tank. News at 6.

I'm curious now - over here you can own a hobby cylinder & have it filled & are responsible to have it tested - you can only rent full size cylinders & the rental company keeps them tested but who pays & how do the cylinders get tested if you are exchanging any old cylinder you got hold of & never get the same one back ?

Steve, I can own up to a 125 tank. After that I have to rent. (I don't know who made that rule, but that's the way I have to run.) The tanks are all tested by air gas and refilled by them at one of their facilities in southern PA and shipped to branch locations. Since I'm located in the middle of no where, I have to rely on a local weld shop for supplies. At this point in time, I don't do enough to justify a big tank.

The gas supplier takes care of tank testing. The DOT rules / fines for transporting uncertified tanks is pricey. One of the suppliers in our area will take old tanks but they charge an extra 75$ to cover testing costs. You don’t get your old tank back, and if your old tank doesn’t pass the test then they charge you for the full cost of the tank. They will let you buy any size tank you want, but you have to save your paper work to prove you own a tank with there label on it. Then they treat you just like any other lease customer, they just swap it out.

As far as can tell, you own the right to a cylinder. You can have it in your shed, no charge, and then you swap it over when empty for a full, tested and good to go one. I don't know what would happen if it goes out of date or is damaged while you have it.

Hmm. For my Argon pressure, I never paid much attention to what y'all are talking about. I just play with it until the pressure is so high that it ruins the weld quality rather than improve it. Then I drop down about 10 PSI. In terms of bottle usage, just use it till it's all out! Seems straightforward to me :/