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Scuba Cylinder Long-Term Storage: Fact and Fiction

Discussion in 'Tanks, Valves and Bands' started by Doc Harry, Nov 10, 2008.

  1. Akimbo

    Akimbo Lift to Freedom Volunteer Staff Member ScubaBoard Supporter

    I nominate this thread be made "sticky" at the top of this forum. :thumb:

    It was (is?) common practice for manufacturers of large (tube trailer size) cylinders to dry and pressurize them with pure nitrogen to 25-50 PSI, post-hydro and cleaning, before paint. The one plant I saw where these were being made used Nitrogen from a cryogenic source, probably more because of the huge volumes required than dryness of the gas. These cylinders were 20" long and have ports at both ends. They were hydroed, cleaned, emptied, dried, and pressurized when vertical so it was relatively easy to dry the insides compared to a single-port Scuba cylinders -- except maybe for needing a bridge crane and a stair case.

    I can't say if this procedure was prompted by these reports or just common sense manufacturing methods. Obviously in this case, cylinders were stored, shipped, and most often used horizontal.
    FritzCat66 likes this.
  2. VooDooGasMan

    VooDooGasMan Solo Diver

    Cleaning the steel tanks has been a thing that got me in the past, Instead of taking LDS word for things I precheck before take in and see what they tell me. Then dive it and empty and check again.

    I was amazed how if a flash rust occurred, it passed for them, or a little bit past flash. now if o2, nitrox was the gas filled, tumble it.

    I had one guy tell me he did his dive class through college, and got bad air do to rust in tank and messed his lungs up a bit and went to hospital over it.

    A month ago a guy that I dive with got his son certified, he got two old al's 80, I opened up and put tank light in and said that ones toast, then put in the other ans said I might dive that one ut it is on its way also. I have one tank that is like the less of his, I use it to blow off, or blow up rib.

    He wanted to dive it and I would not fill but about 500 psi back in, and filled other. I told him to give them back and get newer tanks. now he just told me has got a 110 steel tank japan steel made., I told him to take in to lds and tumble and clean if needed and it will be good for a while.

    I have hilti attachments that I brush my tanks with for light rust. Yet would not like to do for anyone else's tank and be responsible.

    There are so many ways I have stored tanks and they have all been a very well vis Inspection.

    I am dropping off a couple of al 80's to day to a guy that can get them filled at his dive shop, they have a year left on hydro, then a couple more later. I am sending the old ones to others that can use them. with my wife now gone I have no need to have so many tanks for a 3, or 4 days diving. Ten al's and ten steels, should be enough for me, plus storage and pony bottles.

    There is alot you can learn just buy having so many tanks, and taking care of them yourself.

    I doubt I will ever hydo my tanks again as I will not use them that much, although I do over fill them and they have been fine.

    Rinse after diving
    Blow out valve after rinse
    Leave in shade for storage
    Not to hot when filling
    Breathe it down to 1000 psi for easier filling
    Use christo-lube on valves

    Happy Diving
  3. mikes351

    mikes351 Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: South Carolina
    Interesting information you present, now I will have to learn more about this issue. Thanks always good to learn new information!
  4. Reef_Haven

    Reef_Haven Solo Diver

    # of Dives: 500 - 999
    Location: Winter Haven (Central FL)
    I agree. Please make this thread a stcky!

    With the recent tank explosion death in Tampa, this thread really hits home.
    Randy43068 likes this.
  5. Shftrdog

    Shftrdog Barracuda

    # of Dives: 200 - 499
    Location: Sugar Land TX
    Nicely done
  6. Notso_Ken

    Notso_Ken NAUI Instructor

    # of Dives: 200 - 499
    Location: Fairborn OH
    Actually, from my chemist background, and supported by your explanations of the answers, the correc answer is almost uniformly "None of the above", or "It depends." If it is a steel tank, the impact is much more pronounced. Aluminium does not corrode the same as steel. Lay an Al on its side or upright, it does not matter. For a steel tank it certainly does in the presence of any moisture.



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