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Issues with hydro retesting of galvanized steel tanks/cylinders

Discussion in 'Tanks, Valves and Bands' started by lowviz, Sep 6, 2019.

  1. Peter Slater

    Peter Slater Solo Diver

    # of Dives: 50 - 99
    Location: Cleveland
    60
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    Is this an issue with all steel tanks or just older ones? I just bought a set of new steel tanks and would hate to have them condemned.
     
  2. rhwestfall

    rhwestfall Woof! ScubaBoard Sponsor

    # of Dives: 200 - 499
    Location: "La Grande Ile"
    14,417
    15,237
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    LP or HP? HDG or Painted? (HDG = Hot Dipped Galvanized)

    The LP HDG tanks are the ones at "issue". The "new" Faber HDG tanks do not seem to be a "problem", the XS/Worthingtons from 4 to 6 years ago are the "problem"...

    YMMV
     
  3. AustinV

    AustinV Barracuda

    # of Dives: 50 - 99
    Location: NoVA
    337
    131
    43
    I have heard that the hot dip galvanizing is the issue, the painted Fabers of recent years haven't had issues. The "new" Faber hot dipped tanks likely haven't needed a hydro yet, wonder if they will need same test procedure when they start becoming due?
     
  4. rhwestfall

    rhwestfall Woof! ScubaBoard Sponsor

    # of Dives: 200 - 499
    Location: "La Grande Ile"
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    No.... To put it in simple terms, the issue with HDG (then) is that is really is a "shell", and acts independently (to some extent) with the steel body. This is unlike paint. This was how it was explained to me by the staff at Faber/Blue Steel.

    The new HDG Faber 3442 psi tanks are not appearing to be exhibiting this characteristic.
     
  5. rhwestfall

    rhwestfall Woof! ScubaBoard Sponsor

    # of Dives: 200 - 499
    Location: "La Grande Ile"
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    I'll elaborate a little more on my story. The hydro-tester told my LDS he did the test twice (um, the test is different if done a second time - per "law" [CFR]), and failed again. Apparently, this tank is completely in a plastic state.... BS!
     
  6. Peter Slater

    Peter Slater Solo Diver

    # of Dives: 50 - 99
    Location: Cleveland
    60
    19
    8
    They are Faber HP117 with the HDG finish born in December of 2017. From what you said I should be in the clear but I will be careful in a few years when hydro comes around.
     
  7. rjack321

    rjack321 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Port Orchard, WA
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    The HDG problem with related pretest round out advisories goes all the way back to the PSTs of the late 1990s.

    I had never heard the zinc "shell" concept before. My understanding was that the heat applied in the HDG process tended to warp the steel into a slight banana shape. Perhaps it has to do with galvanizing them horizontally so they warp in a droop? When the banana is pressurized to test pressure it tends to straighten and this is misinterpreted as excess expansion.

    If faber is galvanizing differently with no banana-ing then they may be expanding at test pressure more predictably. And not need the round out. Or they just haven't started failing yet. PST initially didn't have any roundout guidance and lots of those cylinders failed when they first came up for test. PST quickly wrote that guidance and its important to realize that the 90% of TP was very specifically chosen - if they had specified 91% that would be the initiation of a hydro test that would be prohibited.

    This issue as been around for almost 20 years. If your shop doesn't know they were badly trained, not doing any scuba cylinders, or just plain idiots.
     
    captain, lowviz and rhwestfall like this.
  8. pauldw

    pauldw Solo Diver

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    I've heard about this sort of thing on SB, but when I asked on my state's FB group about hot dip galvanized HP tanks, no one had a clue whether that's an issue with the company in the state that does hydros. The Faber tanks are 1-2 years old since manufacture. So should I go to California in a few years, or just assume they'll be OK getting hydro'ed here?

    Also, as far as turning failed tanks into grills, does that become a health problem if they're galvanized?
     
  9. JackD342

    JackD342 Dive Shop

    # of Dives: 500 - 999
    Location: Highland Park, IL
    2,514
    1,511
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    No, it is not related to the shape when manufactured. It is related to the zinc bonded layer changing the expansion properties of the bi-metal cylinder versus steel alone.
    The support page at XS Scuba contains multiple documents and a video with an explanation of the Worthington testing issue. Skip ahead to 3:30 if you don’t want to watch the whole thing.
    Changes to the hydro retest — XS Scuba
     
  10. AustinV

    AustinV Barracuda

    # of Dives: 50 - 99
    Location: NoVA
    337
    131
    43
    Those changes apply to the 3442 tanks, I have a pair of original hydro 1999 HP100s that are 3500 tanks, under the E9791 permit. Any differences?
     

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