old steel 72's

[shaggie]

I was recently looking at some old steel 72's in my dads garage. They were manufactured in '68. Besides the obvious-needing tumbling (to clean up the insides since they're empty but no apparant rust) hydro and vip does anyone know if such tanks are worth the cost and effort. I'm thinking they would make a good doubles set .

 

[mike_s]

Actually I bought some empty 72's once and they had not rust and didn't need tubmling.

lots of people really like the Steel 72's because they are more compact and higher density of Aluminum. They are only a little smaller. An AL80 only holds 77cf for example. So 72cf isn't that bad.

I can get a hydro, vis, and air fill for $19 bucks where I live, so that's not a bad investment in some steel 72's. I did have to pay to replace both my valves since they were leaking though.

You can prob pick up a manifold to convert to doubles for maybe $100 and tank bands for about $130. I think that some of the 72's might use a smaller diameter thread on the valve threads. maybe someone else can verify that.

Just remember most of these are 2250psi and they can't be overfilled.

 

[Jim Lapenta]

I have 4 of em and they are great tanks. Two of them do have the narrower necks and valves are hard to find. They are though easily rebuilt. I like em better than al 80's due to their buoyancy characteristics and the fact that they are steel. As far as overfilling it depends on what you call an overfill. All of mine recently passed hydro and though they are from the 50's I regularly get good fills in the 26-2800 range with no ill effects other than more bottom time.

 

[Creed]

72s are the mainstay of my tank collection. For modern diving they work well, and for vintage or a stripped down style diving(for example, warm water with no wetsuit) they are pretty close to perfect. Mine have even had 3000psi overfills from clueless pump jockeys with no ill effects(not that I recommend this under any circumstance). And often, you can still get the + rating for the 10% overfill. I've never turned one down, and never had one fail a hydro or visual. If you don't want them, there are plenty of people who will take them off of your hands.
In regards to necks, you'll commonly see the current 3/4" standard, but I've seen 1/2" as well. Either way, they are most certainly worth salvaging.

 

[shaggie]

Thanks for the input. I was wondering about whether most people were using them at their rated presure or pumping them up some.

 

[Luis H]

A steel 72 only holds 65 cu ft at 2250 psi. It holds 71.2 cu ft at 2475 psi (the 10% overfill). So you really want to be able to get a 2500 psi filling on a regular basis. Although I do dive mine with only 65 cu ft on a regular basis. Even at 65 cu ft they are great tanks.

You should find a hydro tester that will re-stamp the + for the 10% overfill. Any knowledgeable hydro tested should be able to do it. He has to follow CFR 49 (Code of Federal Regulation 49) section 173. It doesn’t involve any more testing, it is just a more stringent passing criteria. Most steel 72 should be able to pass this criterion.

By 1968 it was very common for the neck to be 3/4” straight pipe thread the same as most modern tanks. It is possible (but unlikely) that by that time it would still have the old ½” NPT (National Pipe Tapered) threads. You should be able to tell the difference easily since the ½” NPT thread is a tapered thread with no O-ring. You will see threads sticking out of the tank. Even if it is ½” NPT you can still use the tank. It is just a bit more of a pain to find valves and even service the tank (VIP, tumbling if needed, etc.).


There is one more very…very rare neck size (I happen to have one) that was only produced for Sportways in the early 60’s. It was a ½” straight pipe thread and it has an O-ring. These are very rare and if the valve I got who it was bad the tank would have been close to useless. I just mentioned it just for general information.



One big warning: Make sure you find a knowledgeable hydro facility. Last summer three of my tanks were condemned by a hydro facility that wanted to play it safe since the tanks were old and he didn’t want a Scuba diver to get hurt. To make a long story shot: they had to replace all three tanks with equivalent replacements (vintage steel 72’s). I wasn’t going to accept anything else and after seen the test data I could have reported them for incompetence.

Make sure the hydro facility follows the PST D-100 pre-test procedure. Also known as round out procedure. It applies to all steel tanks. Someone else has been posting it on this message board. You can also find a copy here:
http://www.vintagedoublehose.com/downloads/PST-D-100.pdf

 

[Mack Diver]

I've got two sets of double 72s at the shop, as well as some single 72s. I know one set of the doubles is privately owned by a currently inactive diver. If I recall, they are nitrox rated but need VIP if not Hydro. Anyone who is interested in these can let me know and I'll contact the owner.

 

[shaggie]

Thanks for all that great info Luis. My dads tanks, I'm almost certain are 3/4. I had one of the tank valves out and didn't notice it being unusual in size-just an old school valve with reserve pull handle (J-valve?)

 

[shaggie]

I've got two sets of double 72s at the shop, as well as some single 72s. I know one set of the doubles is privately owned by a currently inactive diver. If I recall, they are nitrox rated but need VIP if not Hydro. Anyone who is interested in these can let me know and I'll contact the owner.

I'll try to get down to the shop next week Mack and take a look at what you got. Still it's hard to beat free tanks. "Free"-my second favorite 4 letter F word!

 

[HowardE]

I was recently looking at some old steel 72's in my dads garage. They were manufactured in '68. Besides the obvious-needing tumbling (to clean up the insides since they're empty but no apparant rust) hydro and vip does anyone know if such tanks are worth the cost and effort. I'm thinking they would make a good doubles set .

I have a set of old Steel LP 72's - I use them as singles for shore dives, or shallow reef dives. They're great tanks. Mine are about that old too... There's a hydro stamp from 1973 on them. They have the + rating, so they're good to 2475 psi (which is where they really have 72 Cft of gas)

I've heard of a few people who have them as doubles. I think Cbulla (here on SB has a set of doubles)