CO2 tank life???

I've recently bought a setup that includes a CO2 tank & regulator. What is the life of these tanks? When do they need hydro tested etc?....I have a sticker on mine from 1995!

mine was also really old, I just exchanged it at a welding supply shop for a newer one,, 20lb tank cost me 19.00 to exchange

I think it varies from state to state. Here in Ohio I believe it is around 7-11 years before re-testing. When you take it in to get filled they will tell you. As for the "life" of them they last a long time unless they get cracked or the valve starts leaking or gets broken. I have a little one from my grandparents that was first stamped in the 1970s and works just fine.

The 5 year hydro testing cycle is a DOT standard as far as I know.

Yep, it's a 5 year hydro test DOT requirement. There is a finite number of times the tank can be filled and emptied, however, this number is quite large. I don't know what the average is, but for our use, the tank will likely outlive us. The tanks expand each time they are filled and subjected to high pressure. They contract when emptied to nearly the same size as before the fill, but not 100%. The hydro test compares the displacement when full vs the displacement when empty. The tank must return to within a specified % of it's empty state displacement and if it does not it will be taken out of service and disabled. There is also a visual inspection the tank must pass both internal and external. Tanks that exhibit corrosion can be cleaned and restored, but they still must pass both the visual and physical hydrostatic test. At least this is how I understand the testing and certification works. I'm not a pressure tank expert, but I remember some of this from stuff I read when I was into diving a lot.

I've heard of steel tanks from the 1930s that are still in use today. I'm sure aluminum has a shorter life span. From my understanding, as long as a tank passes tests, it can still be used.

Catt22 said:

The hydro test compares the displacement when full vs the displacement when empty. The tank must return to within a specified % of it's empty state displacement and if it does not it will be taken out of service and disabled.

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Are you sure about this procedure? AFAIK the procedure for hydrostaic test is to fill with water and pressurise to the test pressure (i think it is usually 1.5 time the design pressure but this would vary from standard to standard) if the tank stays together it passes, if it fails the risk of harm to anyone is minimised by the fact that water was used and not a compressable gas which would suddenly expand if the tank ruptured and could potential seriously hurt/kill someone.
Thats just what I know from industry, testing tanks could be different but I am somewhat suspicious.

mattd2 said:

Are you sure about this procedure? AFAIK the procedure for hydrostaic test is to fill with water and pressurise to the test pressure (i think it is usually 1.5 time the design pressure but this would vary from standard to standard) if the tank stays together it passes, if it fails the risk of harm to anyone is minimised by the fact that water was used and not a compressable gas which would suddenly expand if the tank ruptured and could potential seriously hurt/kill someone.
Thats just what I know from industry, testing tanks could be different but I am somewhat suspicious.

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Yes, I'm pretty sure about it. The tank does not need to rupture in order to fail. It only needs to not return to within a specified % of it's unpressurized displacement. You are right that they pressurize the tanks with water and the reason is that water is not compressible and there is no volume change as there would be if the tank was pressurized with a gas. The sudden volume change is an explosion. The bottom line is that the tank need not rupture in order to fail the test. It can also fail a visual inspection if it has significant dings or deep gouges on the exterior, even though it may pass a hydro test. The safety record for compressed gas containers in the U.S. is amazingly good overall and this is a direct result of our excellent testing and certification standards. Accidents still happen occasionally, but in the big picture they are quite rare. Sometimes people do stupid stuff like paint their tanks and bake them in an oven to cure the paint. This can weaken the metal and cause a failure. The problem is that sometimes there are no visual clues to warn the tech who is filling the tank and he's usually the one that gets killed. Accidents involving pressure vessels are much more common in third world countries where the standards are not well enforced or non-existant for one reason or another.

mattd2 said:

Are you sure about this procedure? AFAIK the procedure for hydrostaic test is to fill with water and pressurise to the test pressure (i think it is usually 1.5 time the design pressure but this would vary from standard to standard) if the tank stays together it passes, if it fails the risk of harm to anyone is minimised by the fact that water was used and not a compressable gas which would suddenly expand if the tank ruptured and could potential seriously hurt/kill someone.
Thats just what I know from industry, testing tanks could be different but I am somewhat suspicious.

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Technically he is right you'd put the tank in either an explosion jacket or similar structure after installing a fill valve. Then the tank is pressurized to 1.5 times rated service pressure. a measurement is taken of the tanks expansion then the tank is drained and another measurement is taken. the tanks must contract to withing a certain% (depends on cylinder material and type) to pass the hydro test. most current shops uses a system of piping in tubes and measure the water displaced in the tubes to measure the expansion and contraction of the cylinder.

Aluminum tanks tends to rupture and fragment when they pop. Steel cylinders tend to rip. both with scare the shot out of you. Beeing filled with water does minimize the velocity transferred to the shrapnel but not to the point one would hydro a tank out in the open.

The working pressure of Co2 is so low that either steel or modern aluminum tanks should least longer than you will be brewing.

every 5 yrs is a Fed dot reg but you wont run into a problem until you try to have it filled and even then all the testing in the world doesn't matter if the fill operator doesn't bother to look.

OH yes, If you ruin the valve just buy another one nothing wrong with the tank. valves are dirt cheap.

GG
Cert fill station operator,gas blender, hydro operator, Diving nut

Catt22 said:

There is a finite number of times the tank can be filled and emptied, however, this number is quite large. I don't know what the average is, but for our use, the tank will likely outlive us. The tanks expand each time they are filled and subjected to high pressure. They contract when emptied to nearly the same size as before the fill, but not 100%.

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Also this doesn't seem right to me either, what it sounds like you are talking about is fatigue failure due to cyclic loading (filling - unfilling). The failure method is not due to the tank expanding a little bit each time (A well designed tank would be under the yeild stress so should not plastically deform) but it is from bassically tiny crack in the surface finish of the tank opeening up just a tiny bit more everytime it is filled, eventually these will open up to a point where there is not enough material to hold the tank together and it will fail, hence why the hydro test is done at a higher pressure than the design pressure - to make sure it fails during the hydro and not once the tank has been fill 2 more times.

Nope. The ultimate failure is due to eventual metal fatigue and it is a direct result of expanding and contracting with each fill even though the maximum stress applied is below the ultimate yield strength of the metal. The hydro test is not done at a higher pressure than the design pressure. It is done at a higher pressure than the working pressure. Obviously it would be preferable that the tank fail during testing and not when in use. The reason that the tanks are tested at pressures much higher than their working pressure is to insure that there is a substantial built in safety factor. It would be downright stupid not to have big margin of safety designed into any pressure vessel. When new, some tanks are legally permitted to be filled an extra 10%. IIRC, this is only permitted until the first hydro test at the 5 year mark. This is clearly indicated on the tank stampings when applicable. Like I said, I'm not an expert on this ****. Just a lowly scuba diver that has done some reading on the subject out of curiosity. Listen to Goodman above. He's been trained in this area and apparently he likes to get wet too.

Catt22 said:

Nope. The ultimate failure is due to eventual metal fatigue and it is a direct result of expanding and contracting with each fill even though the maximum stress applied is below the ultimate yield strength of the metal. The hydro test is not done at a higher pressure than the design pressure. It is done at a higher pressure than the working pressure. Obviously it would be preferable that the tank fail during testing and not when in use. The reason that the tanks are tested at pressures much higher than their working pressure is to insure that there is a substantial built in safety factor. It would be downright stupid not to have big margin of safety designed into any pressure vessel. When new, some tanks are legally permitted to be filled an extra 10%. IIRC, this is only permitted until the first hydro test at the 5 year mark. This is clearly indicated on the tank stampings when applicable. Like I said, I'm not an expert on this ****. Just a lowly scuba diver that has done some reading on the subject out of curiosity. Listen to Goodman above. He's been trained in this area and apparently he likes to get wet too.

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Yes, that is what I was saying the tank will most likely fail due to metal fatigue from the cyclic loading. Design pressure is a different name for working pressure (well at least accurding to Australian standards). I am used to industrial hydrotesting and that would be a fair bit different I would imagine. I did look up the Aus. standards for gas cylinders and it does reference a pressure stretch test but does not give any explaination to it. I still would guess that the standards would ensure that the design/working pressure would result in a stress less than the yeild stress so to avoid plastic deformation of the tank. Maybe this is the reason behind the stretch test in that 1.5 (or whatever) times the design/working pressure might result in plastic deformation but as long as it is below some point it is still ok.

Soooooooo, do you think I should just use this tank until the Co2 runs out?

Yeah dude.

Yeah, should be fine. We sorta got off on a tangent more relating to your title than what it sounds like your actual question was (is it safe to use or not?)
From what Catt22 and GGoodman have said you will just need to get it hydrotested before the next fill, or just swap the bottle.

USE THE GAS THEN,

swap the bottle. easier and cheaper but make sure you get one at least 2 yrs out for the next hydro. or at least that's what i would do but then I cant just swap min out up here.

Pain enough to get it filled.

firefly765 said:

Soooooooo, do you think I should just use this tank until the Co2 runs out?

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What goodman said, with the exception that if you happen to have an aluminum tank, don't swap it unless you can swap it for another aluminum tank. Otherwise just have yours tested and certified. The aluminum tanks are much lighter and easier to handle. It's a significant difference, especially if it's a big 10 or 20 lb tank. I've got a steel 20 lb tank and it's a PIA to lug around when full.

California is 11 years on steel tanks.

mjc said:

California is 11 years on steel tanks.

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The five year testing and certification is a U.S Department of Transportation regulation. IOW, it's a nationwide requirement, not a state by state thing and AFAIK, it applies to both steel and aluminum cylinders.

Where did you get your information? I certainly could be wrong. Are you sure you are not confusing this with the propane tank regulations? I think a new propane tank is good for something like 11 or 12 years, I don't recall which, but that's only for a brand new tank.

Catt22 said:

The five year testing and certification is a U.S Department of Transportation regulation. IOW, it's a nationwide requirement, not a state by state thing and AFAIK, it applies to both steel and aluminum cylinders.

Where did you get your information? I certainly could be wrong. Are you sure you are not confusing this with the propane tank regulations? I think a new propane tank is good for something like 11 or 12 years, I don't recall which, but that's only for a brand new tank.

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i have been testing and certifying these cylinders for years. propane tanks are 12 years from the new date, and either 5 or 7 years after that depending on which type of test is preformed.

as far as it being 11 years in cali for any type of cylinder, thats not correct. its 5 years everywhere.
there is a 10 year test. this is if you see a * next tot he test date. this does not help us home brewers because its is not allowed on co2 cylinders.

earlier there was reference to over filling cylinders. this can be noted next to the test date as well. this will be a +. this also has nothing to do with co2 since it sits around 700 psi.


the +* ratings are only allowed if there is another stamp from the manufacturer of the cylinder. it will have an REE number. this is the maximum allowable expansion. aluminum cylinders can never have this.


there are new restrictions coming out on aluminum cylinders. before 1990 luxfer was making cylinders out of a different aluminum alloy that they are using now. any aluminum cylinder made before then has an extra test it has to pass now concerning the threads on the next. you divers should know all about this by now

sorry for the rant, just trying to clarify some things

Catt22 said:

Nope. The ultimate failure is due to eventual metal fatigue and it is a direct result of expanding and contracting with each fill even though the maximum stress applied is below the ultimate yield strength of the metal. The hydro test is not done at a higher pressure than the design pressure. It is done at a higher pressure than the working pressure. Obviously it would be preferable that the tank fail during testing and not when in use. The reason that the tanks are tested at pressures much higher than their working pressure is to insure that there is a substantial built in safety factor. It would be downright stupid not to have big margin of safety designed into any pressure vessel. When new, some tanks are legally permitted to be filled an extra 10%. IIRC, this is only permitted until the first hydro test at the 5 year mark. This is clearly indicated on the tank stampings when applicable. Like I said, I'm not an expert on this ****. Just a lowly scuba diver that has done some reading on the subject out of curiosity. Listen to Goodman above. He's been trained in this area and apparently he likes to get wet too.

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Your wrong on "When new some tanks are legally permitted to be filled an extra 10%" "this is only permitted until the first hydro test at the 5 year mark". I have three Linde bottles sonic tested last year and filled +10%, a 150 cu/ft nitrogen, 215 cu/ft O2 and a 250 cu/ft helium, all of them with Swastika stampings restamped to make them PC. (screwed up history bottles JMO). These bottles were sold to Germany by Linde during the Hiter era. Linde sold around the world. They're first hydros were 47, 51 and 59 on them. They sat for years until sonic checked last year, they do not "hydro" any more. They passed and are still at +10% over charge filled bottles. Besides history they take a +10% charge and a thicker steel vs newer bottles. I demand them refilled and returned no exchanges. I have 43 more PC corrected (F***ed up restamped) bottles 70 to 260 cu/ft size in storage dated 1928 that should pass sonic test when needed. One other nitrogen dated 1931 passed with a +10% no problem 4 years ago. This now has stout mix gas in it.

Co2 will over time eat into steel bottles, makes one think what carbonic acid inside aluminum bottles is going on? They get an internal tumble and inspection before the sonic check. Carbonic acid eats away the insides of these bottles over time, steel included. 20# Co2 is the minimum size as refills are a waste on smaller bottles vs larger. New is not necessarily better. My dads 1952 72 cu/ft scuba tank still passes sonic checks, now on the 3rd row of them as a hand me down.

there have been documented failures of sonic testing. they have drilled pin holes into cyls and the sonics have missed them.

Jon; i'll add to this what i've been told by my local gas suppliers as well another HBT member in the "Packaged Gas Delivery" business. This with my older gas bottles I had questions about hence why I kept this 43 extra stockpile of these older +% fill large bottles. "The ICC# is the makeup of the tank, the 3AA is the type of steel and the thickness of the wall, 2015 is the max service of the tank to know if it's a 10% overfill tank which must have the most current date should be a + sign. To retest these days they basically scan the tank there really isn't a hydro testing. Steel is as good as aluminum, as long as it passes retest, aluminum lasts longer. Co2 is corrosive eats away at steel walls but not at the rate that effects the gas or liquid inside. When they retest Co2 they remove the valve, tumble, visual inspect inside and hydro. Wash out well and dry as water and Co2 is not good with the cylinder wall. Exceptions for hydro are for tanks used for certain types of gasses.

I've had a couple offers, three just from looking at these 70 to 250, 300 cu/ft bottles been offered $150 each for these older thick walled bottles, they want the whole collection. I'll keep 5 large bottles for extras for my Tig, Mig and nitrogen use. Hell this could become my brewery build cash they were free, haul 'em away. My friends dad a welder passed away (old age) his garage was full of these old Linde bottles some made PC. Bottom line hydro is still in on Co2 bottles or those handling corrosive gases, I was told no worries with my older outdated +10% gas bottles passing test plus there's a demand for them vs newer thinner walled standard pressure bottles. I agree, brewery money for in the bank or my storage area.

BrewBeemer said:

Your wrong on "When new some tanks are legally permitted to be filled an extra 10%" "this is only permitted until the first hydro test at the 5 year mark". I have three Linde bottles sonic tested last year and filled +10%, a 150 cu/ft nitrogen, 215 cu/ft O2 and a 250 cu/ft helium, all of them with Swastika stampings restamped to make them PC. (screwed up history bottles JMO). These bottles were sold to Germany by Linde during the Hiter era. Linde sold around the world. They're first hydros were 47, 51 and 59 on them. They sat for years until sonic checked last year, they do not "hydro" any more. They passed and are still at +10% over charge filled bottles. Besides history they take a +10% charge and a thicker steel vs newer bottles. I demand them refilled and returned no exchanges. I have 43 more PC corrected (F***ed up restamped) bottles 70 to 260 cu/ft size in storage dated 1928 that should pass sonic test when needed. One other nitrogen dated 1931 passed with a +10% no problem 4 years ago. This now has stout mix gas in it.





Co2 will over time eat into steel bottles, makes one think what carbonic acid inside aluminum bottles is going on? They get an internal tumble and inspection before the sonic check. Carbonic acid eats away the insides of these bottles over time, steel included. 20# Co2 is the minimum size as refills are a waste on smaller bottles vs larger. New is not necessarily better. My dads 1952 72 cu/ft scuba tank still passes sonic checks, now on the 3rd row of them as a hand me down.

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Since we're getting picky I can re up the + rating on steel scuba cylinder by performing a couple extra steps. And yes an eddy's current test or visual plus is performed on any aluminum tank I do a visual on or hydro. if it wont pass a visual no point in hydroing a tank.

I saw an aluminum 100 tank at the dive shop that had about a quart of saltwater inside, unknown history but it was a mess he didn't go ay farther than the inspection. The owner took it back not wanting a hole drilled into it, became a portable air compressor tank with quick disconnect fittings added.
So far i'm 7 for 7 with my old 20# Co2 bottles with testing, gave 3 away to my brewing friends as X-mas gifts. I'll keep the other 4 for my use. I'm also 5 for 5 on those WWII era big bottles so I have my pick, the rest i'll take up one of the offers of $150 each. With seven tested at +10% from 150 cu/ft on up, 215, 260 and 300 plus the four 20# Co2 i'm set. This not counting my 260 cu/ft argon and C25 bottles, both +10% stamped and refilled.

The guy at the fire safety shop told me co2 tanks can be certified for 10 years if they are for a stationary placement.

the stationary placement is something i am not sure of. he might be referring to the nitrogen tanks that are used to pressurize certain types if systems. but i am really not sure. i know the fire system companies that we do the testing for come in at 5 years.