Acceptable loses for welding gases- got a leak?

[tarbellb]

While setting up my new shop space I have also reconfig'd my gas line system.

In that process I have now have a (very) slow leak. Before I post what these numbers are,
does anybody have a ref point for what is considered acceptable?


anecdotally- I know when replumbing my Natural Gas for my heater my inspector told me that XXpsi drop/min was within code and acceptable. It was much higher loss then I would have thought, and my system was well within code.

Interested in understanding this and having a ref point. Thanks!

 

[tarbellb]

Uh.... I was at least expecting someone to say "no gas can be leaked, you blow the place up!"

No info or insights?

 

[PCustoms]

Uh.... I was at least expecting someone to say "no gas can be leaked, you blow the place up!"

No info or insights?

Are you talking shielding gas or acetylene?

You've hard piped your building for your welder?

 

[cvairwerks]

For me, acceptible loss rate is zero. With the current pricing structure on both sheilding and fuel gases, any loss is driving my out of pocket expenses up and therefore my shop rates as well.

 

[Sumboodie]

All depends on the gas and the area.

1 cu ft of acetylene in a 10x10 room might be bad.
Same in a 100x100, probably not even noticeable.

I went to use my torch set and found the acetylene was empty . Was a full tank last I used it, so somehow leaks out over a year or two.
Pretty rare I use a torch, just for heating stuff.

 

[tarbellb]

Here's the scenario: Shielding gas only, both 75/25 and 100 argon for my MIG and TIG setup

New 25ft of 1/4" flexible hose line

I connected the line from regulator to welder, filled the line, then shut off reg and welder.

(We're only talking the 25ft of 1/4" hose in volume.)

Right now I'm losing about 5 psi a day from the hose. Water dipped and soap sprayed all connections, nothing bubbles?

My previous setup was rock solid, zero leaks. So I know it's not the welder or regulator. Is this enough to even worry about?

 

[PCustoms]

Here's the scenario: Shielding gas only, both 75/25 and 100 argon for my MIG and TIG setup

New 25ft of 1/4" flexible hose line

I connected the line from regulator to welder, filled the line, then shut off reg and welder.

(We're only talking the 25ft of 1/4" hose in volume.)

Right now I'm losing about 5 psi a day from the hose. Water dipped and soap sprayed all connections, nothing bubbles?

My previous setup was rock solid, zero leaks. So I know it's not the welder or regulator. Is this enough to even worry about?

What pressure are you leaving in the hose?

Why so much hose?

I wouldn't worry about it.

 

[cvairwerks]

You need something better than soapy water to check this leakage rate. Not cheap, but I'd buy a bottle of Leak-Tec 372E and carefully check the fittings and the hose lock ring areas for leaks. Then check all connection inside the welder as well. An 8 oz bottle will run you between 10$ and 20$, plus shipping.

 

[Frog1956]

Are you sure the gas is not leaking through the walls of the new hose?

 

[txvwnut]

You are probably bleeding air at the regulator or internally through the welder(s) solenoid valve(s). My mig and my tig will lose pressure over an extended period after the bottle is closed.

 

[Steve_P]

5 PSI doesn't sound like an excessive loss over a day; the solenoid in the welder will leak down as mentioned. At least mine does.

In addition, gases will pass thru rubber hose, o-rings, rubber diaphragms.... over time. All elastomers are permeable, gases pass thru them, which is why elastomers aren't used in high-vacuum applications.

I shut my tanks off and typically relieve the pressure after use as I don't use it often enough to expect to still have pressure days or months later. I got into this habit because a long time ago I forgot to turn off the valve on the tank for the MIG welder and had no gas a few weeks later; thankfully the tank was already almost empty.

If I was you, I'd spray all of the fittings down again. If nothing, then I wouldn't worry about it. Just remember to shut the tanks off after use.

 

[bwringer]

Temperature changes can cause pressure changes, too, just like your tires. And with a flexible hose, just coiling it differently can make a big difference. There's not a lot of volume in there.

 

[dr_clyde]

Are you leaving the cylinders on when not in use or something?

The amount you’re leaking down is normal and well within the range of acceptable. If you’re losing gas over a period of days or weeks and it’s due to your not closing the cylinder valves, that’s a user error and not the fault of the plumbing.

Shielding gas is cheap, non-flammable and is heavier than air, so no real risk to your life or your wallet. Unless your leak affects the actual welding I wouldn’t worry about it.

 

[bdbecker]

Uh.... I was at least expecting someone to say "no gas can be leaked, you blow the place up!"...

Can't tell if you are joking or not, but you do know that argon and carbon dioxide are nonflammable, right? There is no risk of ignition with either.

The only risk with argon would be asphyxiation if a large quantity were to be released in a well sealed room. Carbon dioxide also has that risk, as well as long term exposure at elevated levels causing health issues, but likely not at the quantity you describe.

 

[tarbellb]

Thanks all, this is good news and about what I was thinking for acceptable loses.
The 25ft hose was pressurized to ~40 psi, and has leaked down to 30psi over couple days.

Yes, I close my tank/reg end of day. I may go days without using again so this is standard practice.

What I think is messing with me is my old setup was literally leak free for weeks even months.
From regulator to welder it would hold the 10-12psi in the hose?

 

[Jack Ryan]

The 25ft hose was pressurized to ~40 psi, and has leaked down to 30psi over couple days.

If you have 25' of hose between the regulator-flowmeter and the welding machine, you had better reinforce the doors as you'll blow them out with gas surge.

OK, I exaggerate, but just a bit.

Jack

 

[Banjorear]

Are you leaving the cylinders on when not in use or something?

The amount you’re leaking down is normal and well within the range of acceptable. If you’re losing gas over a period of days or weeks and it’s due to your not closing the cylinder valves, that’s a user error and not the fault of the plumbing.

Shielding gas is cheap, non-flammable and is heavier than air, so no real risk to your life or your wallet. Unless your leak affects the actual welding I wouldn’t worry about it.

I was wondering the same. I always close the valve on the tank and then purge the welder when I'm done. From your post, it seems like you are leaving the tank valve open. Is that correct?

 

[PCustoms]

Thanks all, this is good news and about what I was thinking for acceptable loses.
The 25ft hose was pressurized to ~40 psi, and has leaked down to 30psi over couple days.

Was the 40psi just a test?

Were you using the solenoid in the welder as a valve at this pressure?

 

[Jack Ryan]

Was the 40psi just a test?

Were you using the solenoid in the welder as a valve at this pressure?

I'm curious as to why you ask. In normal use, the hose pressure could be up to 80psi.

That's why I made the comment about gas surge earlier.

Jack

 

[tarbellb]

Was the 40psi just a test?

Were you using the solenoid in the welder as a valve at this pressure?

Yes just a test, I normally run 10-15psi on my MIG

I was wondering the same. I always close the valve on the tank and then purge the welder when I'm done. From your post, it seems like you are leaving the tank valve open. Is that correct?

See my post below

Here's the scenario: Shielding gas only, both 75/25 and 100 argon for my MIG and TIG setup

New 25ft of 1/4" flexible hose line

I connected the line from regulator to welder, filled the line, then shut off reg and welder.

(We're only talking the 25ft of 1/4" hose in volume.)

Right now I'm losing about 5 psi a day from the hose. Water dipped and soap sprayed all connections, nothing bubbles?

My previous setup was rock solid, zero leaks. So I know it's not the welder or regulator. Is this enough to even worry about?

Thanks all, this is good news and about what I was thinking for acceptable loses.
The 25ft hose was pressurized to ~40 psi, and has leaked down to 30psi over couple days.

Yes, I close my tank/reg end of day. I may go days without using again so this is standard practice.

What I think is messing with me is my old setup was literally leak free for weeks even months.
From regulator to welder it would hold the 10-12psi in the hose?

 

[Jack Ryan]

Yes just a test, I normally run 10-15psi on my MIG

Do you not use a flow meter or a flow gauge?

If you do, and the 25' hose is between it and the welding machine, the static pressure could be anywhere between 20 and 80 psi - it depends on the calibration pressure of the flow meter or the flow of the flow gauge.

If that is the case, you will have a problem with gas surge and the leak will be greater than what you see now.

Jack

 

[MJD1]

Yes just a test, I normally run 10-15psi on my MIG



See my post below

I believe your mistaken, 10-15 cfh. Most regulator/ flowmeters are set to a higher pressure, that's why you get that initial " fifth" surge when you hit the trigger.

 

[Jack Ryan]

I believe your mistaken, 10-15 cfh. Most regulator/ flowmeters are set to a higher pressure, that's why you get that initial " fifth" surge when you hit the trigger.

And from 25' of hose, it would be a blast. But my messages don't seem to be getting through.

Jack

 

[dr_clyde]

I believe your mistaken, 10-15 cfh. Most regulator/ flowmeters are set to a higher pressure, that's why you get that initial " fifth" surge when you hit the trigger.

Yes, welding gas regulators are set at a specific psi (ranging between 10-80psi) and you adjust flow.

When you have a really long hose, it acts as an accumulation tank and gives you a burst of higher flow when the remote is triggered as the hose is after the flowmeter.

Oxy-fuel torches you set pressure, welding gas cylinders you set flow.

 

[MJD1]

Yes, welding gas regulators are set at a specific psi (ranging between 10-80psi) and you adjust flow.

When you have a really long hose, it acts as an accumulation tank and gives you a burst of higher flow when the remote is triggered as the hose is after the flowmeter.

Oxy-fuel torches you set pressure, welding gas cylinders you set flow.

 

[MJD1]

Most welding gas " regulators" are actually flowmeters, not pressure regulators other than the single reduction of pressure.

 

[Mike007]

I went to use my torch set and found the acetylene was empty . Was a full tank last I used it, so somehow leaks out over a year or two.
Pretty rare I use a torch, just for heating stuff.

This happened to me recently. I knew I had a small leak on both my acetylene and oxygen. Didn't bother fixing it. I'll just turn the tanks off when done.... Welp, go to use the torch, both tanks are flat. Left the valves open at some point. It's an expensive lesson.

 

[Sumboodie]

This happened to me recently. I knew I had a small leak on both my acetylene and oxygen. Didn't bother fixing it. I'll just turn the tanks off when done.... Welp, go to use the torch, both tanks are flat. Left the valves open at some point. It's an expensive lesson.

Valve was off. Tank leaked still.

 

[Hakeem]

anecdotally- I know when replumbing my Natural Gas for my heater my inspector told me that XXpsi drop/min was within code and acceptable. It was much higher loss then I would have thought, and my system was well within code.

Interested in understanding this and having a ref point. Thanks!

Interesting. I have zero to offer with regards to your question but here in Chicago Peoples Gas tests it at 3psi and it has to hold it with zero detectable pressure loss for 15 minutes.

 

[Beerhippie]

Can't tell if you are joking or not, but you do know that argon and carbon dioxide are nonflammable, right? There is no risk of ignition with either.

The only risk with argon would be asphyxiation if a large quantity were to be released in a well sealed room. Carbon dioxide also has that risk, as well as long term exposure at elevated levels causing health issues, but likely not at the quantity you describe.

The one place where the argon, in particular, could be a hazard is anything that acts as a "sink"--grease pit, conversation pit, etc--and it would have to be a significantly higher rate of leakage than the OP has.

Argon, beside being considerably heavier than air, is barely miscible with air, so it can "pool" in low spots. The Soviets welded titanium submarine pressure vessels by filling giant "swimming pools" with argon and giving the welders prototype space suits to wear. "Will be fine, Comrade!"

CO2, OTOH, is highly miscible and doesn't pool except in perfectly calm condition free of the slightest air flow.

Personally, I'd move the flow regulator to the welders and use hard pipe to the tanks.

 

[tarbellb]

Update:
First @MJD1 and @dr_clyde are correct about flow not psi. I have my regulator set at 15cfh

Also, yeah there is a surge of gas on the first trigger pull. Nothing crazy, a noticeable higher output for a 1/2 sec then back to norm for the welding session.

I do have a slow leak from the machine to regulator, takes about 24hrs to drop 15 to 0cfh after ive shut the tank valve.
An acceptable loss for me

 

[Milton Shaw]

Nobody has mentioned the ones I found on my system. The packing nut on the cylinder was leaking when shut off and draining the hose down. Also leaked when on, I think that is why they recommend back seating the valve by unscrewing the valve all the way open, instead of just opening a half turn or so. Soapy water will tell really quickly, though not on Oxygen leaks just use straight water.

 

[Jack Ryan]

Nobody has mentioned the ones I found on my system. The packing nut on the cylinder was leaking when shut off and draining the hose down. Also leaked when on, I think that is why they recommend back seating the valve by unscrewing the valve all the way open, instead of just opening a half turn or so. Soapy water will tell really quickly, though not on Oxygen leaks just use straight water.

You still have that type of valve in service? I don't think I've seen one for decades.

The modern valves are not screwed all the way open, just enough to get full flow.

Jack