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Dade County FL Rumor

Discussion in 'Tanks, Valves and Bands' started by Ed Jewell, Feb 27, 2002.

  1. Ed Jewell

    Ed Jewell Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Melbourne, FL/Shavertown, PA
    174
    1
    18
    In the Melbourne, Fl area I've heard the rumor that all the LDS in Dade county are simply refusing to fill any aluminim tank that is older than 15 yrs. Can anyone shed any light on this. If true, then it must be due to older tanks (those manufactured prior to 1988) being more suceptable to the SLC issue.
     
  2. ebbtide

    ebbtide Nassau Grouper

    190
    0
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    not exactly sure but is this what you are
    refering to
    http://www.undercurrent.org/UCnow/articles/AlTanks200008.shtml
    witch says the fallowing : and this is a quote :


    Aluminum Tank Controversy Continues
    safely separating truth from fiction


    from the August, 2000 issue of Undercurrent


    Since our March article on the dangers of Sustained Load Cracking
    (SLC) in a small number of older aluminum tanks, we've been hearing
    lots of misinformation within the industry regarding this problem and
    what's being done about it. Let us set the record straight.

    There's no question that SLC has led to catastrophic ruptures of
    aluminum scuba tanks manufactured before 1990 from alloy 6351-T6.
    The U.S. Department of Transportation (DOT) has files on three such
    aluminum tank explosions, including the 1998 maiming of a Riviera
    Beach, Florida dive shop worker that we reported.

    While a San Diego newspaper reported that on June 4 an instructor
    was injured "when a scuba tank exploded at La Jolla Shores Beach,"
    that wasn't correct. Bill High, whose firm Professional Scuba
    Inspectors, Inc. (PSI) monitors such incidents, tells us that the
    instructor actually was burned when he turned on the valve of a
    cylinder containing a high percentage of oxygen and the mixture
    spontaneously combusted (a risk of gas with high oxygen mixes).
    There was no explosion or internal damage to the cylinder. A few days
    later a fatal explosion did occur at a popular dive site in Ontario,
    Canada. But the tank that ruptured was a steel military surplus ballast
    cylinder being used for diver air storage. The mass media don't
    always make such fine distinctions, so be wary of accepting news
    reports at face value.

    Additional confusion has arisen from DOT's listing of scuba tank
    brands and models most likely to be made from 6351-T6, which we
    published in March. Some shop owners and divers have mistakenly
    assumed that the manufacturers are recalling the listed tanks. In fact,
    no recalls have been announced. The tanks are still in service,
    providing they pass a visual inspection (VIP) annually and a
    hydrostatic test every five years. That's for U.S. tanks - other nations
    have their own testing requirements. The leading manufacturer,
    Luxfer, has just issued a new policy statement requiring that every
    Luxfer 6351-T6 aluminum scuba cylinder be visually inspected at
    least every 2.5 years and that the cylinder neck be tested with an
    eddy-current device such as Visual Plus or Visual Eddy (using
    electromagnetic waves to detect cracks in tank threads that might not
    be visible to the naked eye) or equivalent non-destructive testing
    equipment. These requirements are in addition to DOT-mandated
    VIP and hydro tests. For cylinders in heavy use (for example, those
    filled five or more times a week), Luxfer recommends visual inspection
    every four months.

    Luxfer also recommends that eddy-current devices be used only on
    6351-T6 cylinders, because the procedure has produced "false
    positive" readings in its newer 6061-alloy tanks, which it began
    producing in mid-1988 in the United States. There have been no
    reports of SLC in tanks made from the harder 6061 alloy. PSI further
    recommends that VIPs be performed just before and after each
    hydro-test, since the hydrostatic procedure (in which the tank is
    pressurized with water to 5/3 of its working pressure) can make cracks
    more visible.

    Not all testing facilities follow these procedures. High points out that
    some dive shops require and charge for eddy-current testing
    not only on all aluminum cylinders, regardless of their alloy, but
    also on steel tanks, though there is no history of SLC in 3AA steel
    cylinders. So don't pay for unnecessary tests. Ask a few questions
    about testing procedures, and be sure you're comfortable with the
    answers.

    If you're unsure whether a tank you may own or rent was made from
    6351-T6, check the earliest hydro test date (date of manufacture)
    stamped on the tank's shoulder. If it's earlier than 1990, assume it's
    made from 6351-T6 and follow the above procedures just to be on
    the safe side.

    If a U.S.-made original-owner Luxfer tank is more than 10 years old
    and fails either a VIP, hydro or eddy-current test, you can return to
    Luxfer with $50 for a replacement. All returned tanks are subject to
    Luxfer's own examination of the tank. (Call Luxfer at 1-909-684-5110
    for specific details.) These policies apply only to condemned Luxfer
    tanks. No other manufacturers offer a return policy.

    If your tank is made of 6351-T6 and passes all the tests, it's probably
    safe - especially since Sustained Load Cracking takes years to
    develop to the detectable (or dangerous) point. Only you can
    determine your own comfort level in continuing to use it.

    -D.L.
     
  3. tentacle13

    tentacle13 Angel Fish

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    In Seattle also. There are a couple dive shops that will not fill tanks older than 8 years old. Even if they have current hydro and vis tests. As a person who studied and has worked with lots of metal, I understand to some degree. In the upcoming years they may sway into some sort of sonographic inspection. Looking for structural damage within the wall of the tank.


    time will tell.:doctor:
     
  4. Ed Jewell

    Ed Jewell Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Melbourne, FL/Shavertown, PA
    174
    1
    18
    Yeah, I can understand a LDS turning away aluminum cylinders made prior to 1988, because these are the ones with the sustained load cracking issues (aluminum alloy 6351). But I can't understand why a tank made in 1994 (aluminum alloy 6061, nonsuspect) should be turned away just based on the date alone. An aluminum cylinder made in 1994 hasn't even gone through two hydostat cycles yet. Yes, I can understand if the cylinder showed signs of abuse, failed visual, failed hydro, etc., but not based on age alone.

    I think you hit the nail on the head when it comes to these LDS's adopting this policy just to raise income from the sales of tanks.
     
  5. MikeFerrara

    MikeFerrara Instructor, Scuba

    14,095
    30
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    Let an lds comment here. We still fill older (6351) tanks. Most others do and the odds are not to bad. But... they scare me to death. We would love to stop filling them and we do not make much selling a tank. The problem is a tank almost always blows when being filled. The diver risks nothing. I get killed all because the guy was to cheap to spend the money on a new (safer) tank. Instead he buys junk at some yard sale then wants me to stand next to it while its filling. Not a good deal for me. Eventually we will set an age (or some other limit) on tanks. Tanks are cheaper than plane tickets, buy a new one every ten years or so. Please.
     

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