Test dates on gas cylinders

[Wowthatishot]

My gas supplier will only swap my gas cylinder, rather than refill. I saw on this board that it is a good idea to check the test dates on the gas cylinder before accepting it. Where can I find the test dates on the cylinder?

I'm kind of a safety freak and really want to know before I bring the cylinder home!

Thanks, this is a great forum!

[brianw]

cylinder dates

the date should be located on the shoulder of the tank. The tank is ok for 5 yrs after the date unless there is a star next to the date in which case it is good for 10 years. Most CO2 cylinders (all that I know of) are only good for 5 yrs due to corrosion from CO2.

As a side note, the only thing the test date affects is whether or not the tank can be filled. It does not mean you cannot use/ transport a tank that is out of date. Common sense prevails, if the cylinder is far out of test than you may not want to use it. Also a single arc burn will cause a cylinder to be junked.

[Franz]

The biggest thing you need to be concerned with relative to test dates is your supplier's policy on who pays for retesting. Some suppliers love to slip an almost out of date cylinder onto a lo volume user if the user is responsible for testing cost cause they know the cylinder will be a year or more beyond date when it comes back, and they can charge the user for testing.
They also know they can't pull this crap with volume users if they don't want to play catch the cylinder on the loading dock.
If you're a lo volume user, you have every right to refuse a cylinder that will expire while it's in your posession.
Swapping cylinders is the normal procedure for most suppliers because it is more time efficient than filling individual cylinders as they come in. In my area suppliers won't fill the customer owned cylinders from places like Harbor Freight or Northern Hydraulics, and will only fill cylinders they supplied.

[pontiac]

Here's a shot of the date code on my cylinder

[Wowthatishot]

So, if I'm reading that stamp correctly....That bottle was inspected in 1997 and that inspection is good for 10 years because of the star stamped next to the 97+?

[pontiac]

Yes.. the star is for 10 years and the plus allows for 10% over standard on re-fill

[Snidley]

It really should be a non issue for the end user. The gas suppliers usually only lease the use of a cylinder size - not specific cylinders. This way they can just exchange and can refill at times which is more convienent. They own the cylinder - it is their responsibility. The cost of general maintenance other then damage is built into the annual lease and gas cost. Around here the only cylinder you can buy is a propane one.

As for the date stamp - the tank should be good for refilling for 5 to 10 years depending on the gas. The cylinders after that time are taken out of service and sent for testing. The valve is removed, visual internal inspection, tumbled clean if there is corrosion, a new valve installed and then pressure tested. The external body is measured - then the cylinder is overpressurized by xx%(I forget the percentage) the when the pressure is released cylinder is immediately remeasured and if it does not come with in x% of pretest measurement, it is returned with a couple of drill holes. They can make nice fence posts. Otherwise it is returned to service with a new date stamp - and generally with a nice new paint job.

If you are not sure of the answers you get from your sales rep about the cylinders, talk with the guy who fills them on the dock.

[Roger]

This link shows hydro being done and explanes process.

http://www.deep-six.com/page37.htm

This link has DOT regulation governing hdrostatic testing of cylinders.

http://hazmat.dot.gov/regs/173.34.htm

Burst disk on cylinder valve is stamped with pressure at which it will burst and should be the hydrostatic test pressure.

As stated before cylinder valves with pipe threads are replaced by new valves after hydro.
Scuba cylinders use straight threaded valves with O-ring seals so valve threads aren't damaged by installation.

[Hobart210]

Good link there Roger. I do alot of work with hydro testing cylinders wheter they are DOT rated or non DOT. DOT is on the prowl everwhere right now. My company has been pulled over a few times in the last week checking Log sheets and MSDS forms. For most people here this doesnt mean a thing BUT watch out. Anytime you transport a cylinder in any vehicle it MUST be strapped down as to not roll around. Also you must carry a manifest that the supplier of the cylinder should give you everytime you get a fill. Without this you are subject to a hefty fine if caught. We have paid over $5k on several occasions!!