Used tanks

[Caseyd1971]

Hey I am looking at buying some old steel tanks last hydro was in 84. Both are full of air. Is it a bad idea to buy tanks made in the 70s. Any help would be appreciated. Thanks

 

[CptTightPants21]

While steel tanks will last for 50 years plus, I prefer to buy tanks that are younger than 15 years, and ideally less than 10. There are too many good deals in the younger age ranges for me to deal with tanks that were made during the Carter administration.

 

[tbone1004]

for steel 72's, I wouldn't hesitate if the price is right *$50-$75 depending*. the risk is that if they are lined, they are basically worthless, so you have to be careful of that. Aluminum I would pass

 

[CT-Rich]

I am retiring a pair of 72s that were manufactured in 1972. They have developed some pitting on the outside. I wouldn't pay a lot for them and they may not pass hydro or visual. I know there are much older tanks. If in good condition, they can last forever.

Old AL tanks I wouldn't invest in. My dive shop has announce that they are no longer going to fill/ service tanks manufactured prior to 1990.

 

[Caseyd1971]

Thanks so much for the info. I will be paying 100 bucks for two of them. So if they don't pass I guess it won't hurt to bad.

 

[2airishuman]

Hey I am looking at buying some old steel tanks last hydro was in 84. Both are full of air. Is it a bad idea to buy tanks made in the 70s. Any help would be appreciated. Thanks

I have quite a number of steel cylinders that were manufactured in the 60s and 70s. Generally, they have been out of hydro when purchased.

There are several things to watch and to consider.

1) Some older cylinders will fail the visual inspection that precedes the "hydro" test, due to pitting, with internal pitting being the more common cause of failure as well as being more difficult to detect before purchase. (Actual failures of the hydrostatic portion of the test are very rare).

2) Some older cylinders will have internal liners or internal corrosion which, while not disqualifying in and of themselves, have to be removed prior to hydro so that the cylinder wall is visible for inspection. In some areas there aren't any places that will provide this service for a reasonable price. In my area there's a hydro shop that will do it for $18, but that's unusual. You can buy or build a tumbler and clean up the insides yourself, but that's quite an undertaking.

3) Consider the total acquisition cost including: purchase, hydro/vip, and any valve work or valve replacement that is needed. Typically the valves need to be disassembled, cleaned, and reassembled with new o-rings and ideally a new burst disc.

4) Watch out for non-standard neck threads. Some older cylinders have M18 threads, and replacement valves aren't readily available so you want to be sure the cylinder comes with a usable valve. Some older cylinders have tapered threads, which are more of a hassle for VIP, and as a result some shops won't VIP them and others won't even fill them. While you can get valves, both new and used, for cylinders with tapered threads, there isn't as much selection, and the new ones are all expensive.

5) Be sure of the cylinder you're buying. Watch out for much older 3A (rather than 3AA) cylinders, they're very heavy and not at all practical. Watch out for lower pressure cylinders (3AA1800) unless that's what you really want, they tend to be floaty (but can be useful if you're trans-filling and want to make the most of your gas supply).

6) Check on the availability of and need for + ratings. Most dive shops won't fill to the original rated capacity (including the 10% overfill) unless a + rating is stamped at the most recent hydro, although this varies regionally and between shops. Some hydro places won't stamp a + rating on any cylinders, some won't stamp them on older cylinders that don't have the REE stamped on the cylinder by the manufacturer, and some will do it for certain brands but not others.

 

[captain]

The lining is not a reason for disqualification, I have a lined 72 that continues to pass hydro. Actually the lining makes detection rust easier because just as rust under the paint on a car causing bubbling of the paint it does the same to the lining. No bubbling visible, good to go. My oldest tank is a 72 made in 1957.

 

[tbone1004]

many hydro shops won't hydro them, there are some, they are out there, but many won't. Many dive shops won't VIP them either

 

[simonbeans]

Take your tanks to a hydro facility yourself. Most don't care what tank it is, as they hydro all sorts from fire extinguishers, scuba and many others. As to VIP, take the class and do your own visuals. Not hard. Most of my tanks are 71.2 and pass every 5 years.

 

[2airishuman]

The lining is not a reason for disqualification, I have a lined 72 that continues to pass hydro. Actually the lining makes detection rust easier because just as rust under the paint on a car causing bubbling of the paint it does the same to the lining. No bubbling visible, good to go. My oldest tank is a 72 made in 1957.

All true and it depends on the condition of the lining. I have one cylinder right now with an intact liner. It had been stored outdoors under the edge of a roof with a blown burst disc for years and filled 1/4 of the way with water before I bought it. The liner is the only reason the cylinder didn't corrode far beyond the point of usability. I washed it out with hot soapy water, rinsed, dried, overhauled the valve, and sent it off for hydro, and it passed and got a +.

Other cylinders where the liner was coming loose in dozens/hundreds of places, leaving little bubbles. Then the liner had to be removed because there's no way during the visual inspection to select which of the bubbles has the deepest pit behind it. That one passed, too, after the liner was shot blasted out.

I've had one cylinder where I took a quick look inside and put it in the scrap bin, the corrosion was so bad. I've had two others that I never looked at before dropping them off for hydro, that were condemned. Out of maybe 20 older cylinders I've bought.