Several years ago, I inherited a professional Oxy-Acetylene setup. 5’ tall tanks, heavy duty stand, cutting torch and smaller welding/braising torch. It’s something that’s always been in the back of the garage gathering dust.
Lately I’ve been futzing around with metalwork, Lathe, milling, grinding, and I just picked up a cheap little mig welder and am getting more and more comfortable with working with metal.
The Rig in question is easily 25 years old. The tanks are full and I’m pretty sure everythings okay, but are they something that would fail testing due to age? I know CO2 and SCUBA tanks need to periodically be tested, I’m pretty sure these do too.
Oxygen tanks, like CO2 tanks and SCUBA tanks, are under a very high pressure. Ususally the pressure is fluctuated by filling and emptying the tanks. This causes stress and strain to the material the tanks are made of and they explode. Your high pressure oxygen tank will need a hydrostatic test before anyone will refill it. There is a date of the last hydro done on the tank stamped somewhere near the valve.
Every time I’ve ever bought gas, I’ve dropped the cylinder off and they’ve replaced it with a different, full cylinder. A $2 charge is added for “maintenance”, Although the option to refill was available, I’d have to wait till the next day (CO2 for my kegerator, specifically), because the shop in Santa Fe gets its gas from Abq. Similarly, when I worked on campus and had to get a new bottle of O2 or Acetylene from the “Bottle Shop”, we’d exchange that as well.
I would be more concerned with the valve failing, than the tank itself. Gas tanks, especially older ones, are very thick. Without doing any calculations, I’d bet money that the number of times the stresses on the tank have been cycled (i.e. filled and emptied) are orders of magnitude less than the level that would cause a fatigue failure. hlanelee, do you have a cite showing tanks that have exploded purely due to (proper) filling and emptying?
Just hope they are not rental tanks. I inherited an oxy/acetylene setup from a cousin and rarely used them. About 10 years later I wanted to used them so I loaded the tanks into my truck and went to the nearest welding supply house to get them refilled. They guy looked at the tanks, wrote down the stamped in serial numbers and made a phone call. He came back and told me I owed over $200 in rental fees for the tanks. If they have the name of an air and/or gas company molded into the neck just below the threaded part for the safety cap, they are rental tanks. I negotiated a rental return/purchase of tanks deal and saved about $100 of the rental fee. That was about 6 years ago and the tanks are still mostly full sitting in the corner of my garage. But I own these.
They very well could be. They say Acetylene Service Co. Denver Co. on the Oxidiser tank. It’s still got 1700 psi on the gage…the other tank is rotated so I can’t see how much it’s got.
The time or two I futzed with them, I pretty much ended up with a lot of popping as the flame blew out and soot all over everything. I have about 10-15 minutes lifetime experience with the rig, and I didn’t do the initial lighting.
Here’s a Wikipedia Link concerning hydrostatic testing. I don’t know that a tank has ever failed, solely due to proper filling, but I believe that certain authorities (such as DOT) are concerned enough that it could happen that they require testing.
The issue here is purely one of age, not cycling. While dad DID make some heavy duty equipment for a couple of years, I don’t think the tanks have been cycles more than a half dozen times, and not within the last 15 years.
If they are rental tanks you may have to negotiate something like racer72 did. I own both the large oxy/acetylene rig and the small “totes.”
I wouldn’t worry about the integrity of the tanks at all, imo. However…the hoses can and will dry rot. Also, the regulators have bellows in them, and springs that will become stiff, seized and generally no good over a long period. [of non use]
Most people don’t know this (at least those who don’t work with this stuff) but you don’t own those specific tanks as much as you own 2 tanks. What I mean (assuming they’re not rental tanks) is that you go to a gas supplier and give them 2 tanks empty and they give you 2 full ones. So… I wouldn’t worry about the tanks as the first time you get new tanks your tanks will go into the rotation of the supplier and it is his problem to service them.
A coule other things. AVOID carrying the tanks in an enclosed vehicle. It’s always better to use a pick up or other open vehicle. And, NEVER carry an acetylene tank on it’s side.
Do your hoses have check valves in them? The check valves won’t allow burning acetylene to migrate backwards into the tank and explode, thereby killing you and ruining the day of those who love you.
I think if I ever get to the point of cutting metal (as opposed to using thin enough gauge to just trim to shape), I’ll see about re-evaulating every part of that rig. The sparkers and the chalk are still good, everything else is up for consideration. I’m getting to the point now where I think some official classes would be most helpful. I’m doing some really cool stuff with the lathe and mill, but I’m sure I’m low on street smarts.
I’ve got an Avalanche, and the Acetylene tank is only about 3 feet tall, transporting it upright shouldn’t be that big a problem (there’s something in the tank, isn’t there?)
Sure wish my Dad were still around for help and instruction. I didn’t get into this stuff til after he passed away.
There is a local gas supplier and I had some questions about the differences between acetylene only vs oxy/acetylene. There was a guy there who was wealth of information. You may try a local welding shop, or your supplier and you may be surprised at the help you might receive.
I’ve been using oxy/acetylene in HVAC work for 17 years or so, and I’m comfortable in this limited application. (some cutting, but mostly copper to copper or copper to brass brazing.) I’ve done little with aluminum or steel. I use mostly “Dynaflow” or other silver bearing brazing rod. Of course, the higher the silver content the different procedures and performance. (like lower melting point)
I’m enjoying the stuff I’m confortable with so far (The MIG welder seems to be easier to use than I expected), it’s a pity as I inherited a COMPLETE O/A setup and stick welder with a TON of rods…they’re all going to waste as it seems the technology has moved on. Now it’s MIG/TIG and Plasma or nothing.
Acetylene in pure form will spontaneously decompose (explode) if pressurized much beyond ~12 psig. Inside the cylinder is a ceramic (IIRC older vessels used asbestos) spongelike matrix which holds acetone. The acetylene gas is ‘dissolved’ in the acetone, stabilizing it for pressurization beyond 12 psi. When you open the bottle valve, you’re letting the acetylene out, but retaining the acetone. Lay a bottle down and open it, or knock the valve off, and things get dicey, quickly.
I have a short video which I use when teaching HazMat classes-it shows a rural fire crew making initial attack on what looks to be a small fire in a barn. A minute or so into the video, an acetylene cylinder ruptures, engulfing four guys in a fireball. The explosive force knocks down the person with the video camera. A healthy respect for the angry genie in the bottle is a good thing.
It’s been almost 40 years, but the SCUBA shop I used to have my tank filled at, had a tank that blew up during filling on display.
Picture a SCUBA tank cut on the diagonal, and rolled out flat. It had rust inside it. Apparently the owner had run the tank flat out, and allowed some moist sea air into the tank.
There is a reason tanks are put into a tank of water during filling, and hydrostatic tests are required.
As far as taking tanks back to the welding supply shop, I don’t know that you are allowed to. The shop I do business with, an Airgas franchise, delivers. If you are in a rural area, that might be a problem. I do take in my little peanut rig though.
I worked for about a dozen years at a plant that refilled gas cylinders, including acetylene tanks and O2 tanks. As has been mentioned, oxygen and acetylene tanks are of very different construction. O2 tanks are simply hollow steel, and are hydrostatically retested every 5 or ten years (star stamped) depending on the manufacture of the tank. Older tanks typically are 5 year. Tanks are internally inspected for rust as part of the testing process. Tanks that fail hydrotest typically do not fail catastrophically. Acetylene tanks are not hydro tested as they have a solid mass porous filler in them. They receive visual inspections.
Properly tested tanks do not fail catastrophically when filled. There is a frangible disc safety in the valves so that if the pressure is too great, the disc will burst and the tank will vent safely (but it’s damn loud when they do). Acetylene tanks have fusible disc safeties, so in the event of a fire the safety will melt, venting the acetylene/acetone. This does turn the tank into an unguided missile in the event of a large fire, as I have witnessed. They go quite a distance into the air. Scary stuff.
I called a local vendor and their feelings are: The tanks are fine. I’ll have to have them tested when (if) I ever need them refilled. The company stamped on the tanks is no longer in business so I effectively own them.
I figure I need to find a community college to learn how to use the stuff, replace the hoses, and call it good.
That’s if you have them refilled. As I said, in many places you simply drop off your empties and they hand you 2 [other] full tanks. In my neck of the woods, the refilling is done by the suppliers, who pick up and deliver to the wholesale shop/ distributor. There is no equipment to refill at the point you purchase. I’ve purchased brand spanking new tanks, used them and returned them for refills and received tanks that looked like they travelled a million miles. I don’t/didn’t care. I own 2 tanks generally. I go to my vendor and drop them off at the dock. I go to the counter and I’m given 2 [different] full tanks. There is no re-filling at the vendor’s facility.
