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Best tape for tapered LP72 threads?

Discussion in 'Tanks, Valves and Bands' started by MrVegas, Feb 10, 2019.

  1. MrVegas

    MrVegas Nassau Grouper

    # of Dives: 100 - 199
    Location: Ohio
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    I'm going to take two old LP72s with 1/2 inch tapered threads in for hydro and visual pretty soon. I was just curious what tape people usually use on the threads when putting the valve back in the tank. (I'm not going to try to do anything myself, but I might actually provide the tape.)
     
  2. runsongas

    runsongas Great White

    # of Dives: 500 - 999
    Location: California - Bay Area
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    Teflon tape. Mil spec or the NIBS aa58092 grade.
     
  3. 2airishuman

    2airishuman ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: Greater Minnesota
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    I have been using 99%+ teflon tape intended for oxygen service. It seals much better than the thin white stuff in the plumbing department at the big-box home center.

    The stuff I got is no longer available on Amazon, but here's the link. You might be able to find something similar:

    https://www.amazon.com/Green-Thread...tape&qid=1549856633&s=gateway&sr=8-5-fkmrnull

    Also, it helps considerably to chase the threads on the valve and cylinder with a die and tap to get the last of any crud out. Threadcutting is not in compliance with DOT regulations but my interpretation is that using a tap for cleaning purposes without cutting new threads is OK.

    And I have had problems with them leaking when they come back from hydro, so your concern is not misplaced.
     
  4. rjack321

    rjack321 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Port Orchard, WA
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    I don't know anyone with actual tapered taps?
    You can just go round and round with a dental pick too.
     
  5. Bob DBF

    Bob DBF Solo Diver

    # of Dives: I just don't log dives
    Location: NorCal
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    One more reason to know a plumber.


    Bob
     
    Ghetto Diver likes this.
  6. MrVegas

    MrVegas Nassau Grouper

    # of Dives: 100 - 199
    Location: Ohio
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  7. 2airishuman

    2airishuman ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: Greater Minnesota
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    Or a wire brush. You have to be careful to clean out any debris that falls into the cylinder.

    1/2" NPT taps are available at any home center in the plumbing department. They are not expensive. 3/4" NPSM taps are more difficult to get.
     
  8. divad

    divad Solo Diver

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    Or a brass wire brush.
     
  9. Ghetto Diver

    Ghetto Diver Solo Diver

    # of Dives: I just don't log dives
    Location: Beerfield Beach, FL
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    I believe these are 1/2 nGt not npt.
    They are close, but not the same.
    I use a ss wire brush. Plumbing tape worked too.
    Ymmv

    Eta: I seen this spec'ed somewhere else but here's one. (At work)
    SCUBA Valves | Dive Gear Express®

    I meant to confirm when I pulled mine, but did not.
    No way would I chase these with a npt tap/die
     
  10. 2airishuman

    2airishuman ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: Greater Minnesota
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    The only difference between NGT and NPT is the minimum number of mating threads. It's the same thread form, size, spacing, etc.
     

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