I am putting together a set of lp72's. I am getting ready to put the new valves in. Do I need lube the threads of the tanks and valves? If so is silicon ok to use? These tanks will not be used for nitrox.
Thanks
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Tank Lube...
- Thread starter smorneau
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Generally speaking, lube is needed on valve threads to help limit/prevent dissimilar metal corrosion issues between the aluminum tank and the chrome plated brass valve. It is also needed to prevent the threads from galling in aluminum tanks.
There is no real need for lube on the valve threads with steel tanks, although it is still often done. You do however want to lube the tank valve o-ring to allow it to properly seat between tank and valve. Silicone grease is fine as long as you won't be exposing it to O2 percentages over 40%.
There is no real need for lube on the valve threads with steel tanks, although it is still often done. You do however want to lube the tank valve o-ring to allow it to properly seat between tank and valve. Silicone grease is fine as long as you won't be exposing it to O2 percentages over 40%.
T. Bix
Contributor
Let's say next year you want to start using Nitrox and you are PP blending, Now when you clean your tanks you have to deal with a poor decision to save a few pennies last (this) year and have to get ALL that silicone out of the threads. Go get some Tribolube or Cristolube and do it right. And next year when you change your mind about breathing gas you'll be glad you did. FWIW: Aluminum or steel I always give the threads a little lube just so it comes apart easier next year.
Some cylinder manufacturers do not recommend applying lubricant to the valve o-ring. A slippery o-ring can slip during valve tightening and become extruded under pressure.
If your cylinders are not being used for Nitrox, generally it matters not which lubricant you use for the valve threads to prevent bimetal corrosion. Only 3 different lubricants have even been formally tested (High Purity Goop, Molycote 557 and Dow Corning 111), and all 3 worked better than nothing at all.
Even if you use Christo-Lube, you'll still have to clean the old (dirty) lubricant from the valve threads if you want your cylinder O2 clean. I have a nylon tubebrush that can be mounted into my screwdriver and, with a lot of soapy water, gets the cylinder threads shiny and clean.
http://www.luxfercylinders.com/supp...or-luxfer-aluminum-alloy-cylinders-and-liners
Cichy, Francis, Hilbert Schenk, and John J. McAniff. Corrosion of Steel and Aluminum Scuba Tanks, University of Rhode Island Technical Report 62, 1978.
If your cylinders are not being used for Nitrox, generally it matters not which lubricant you use for the valve threads to prevent bimetal corrosion. Only 3 different lubricants have even been formally tested (High Purity Goop, Molycote 557 and Dow Corning 111), and all 3 worked better than nothing at all.
Even if you use Christo-Lube, you'll still have to clean the old (dirty) lubricant from the valve threads if you want your cylinder O2 clean. I have a nylon tubebrush that can be mounted into my screwdriver and, with a lot of soapy water, gets the cylinder threads shiny and clean.
http://www.luxfercylinders.com/supp...or-luxfer-aluminum-alloy-cylinders-and-liners
Cichy, Francis, Hilbert Schenk, and John J. McAniff. Corrosion of Steel and Aluminum Scuba Tanks, University of Rhode Island Technical Report 62, 1978.
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halocline
Contributor
I have also heard that the tank valve o-ring is installed dry to help guard against extrusion. I suspect the o-ring material and hardness has a lot more to do with it. I would not worry about using silicone for air tanks (or banked nitrox) and when/if the tank is to be used for partial pressure blending you'll have to completely O2 clean the tank and valve anyway. So worrying about removing a little silicone from the tank valve threads is silly.
That said, I end up using tribolube because that's what I have. I'd almost rather use silicone or molycote; both seem much thicker and better suited to preventing galvanic action. Since you're taking the valve out annually (in the U.S. anyhow) it's yet another thing that probably does not matter much.
That said, I end up using tribolube because that's what I have. I'd almost rather use silicone or molycote; both seem much thicker and better suited to preventing galvanic action. Since you're taking the valve out annually (in the U.S. anyhow) it's yet another thing that probably does not matter much.
Using Christolube will not reduce the cleaning burden down the road if you switch to nitrox, etc. Clean means clean and you'll need to remove all the lubricant in the cleaning process regardless what you use.
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A lubricant on the tank o-ring allows it to seat properly in the space between neck and valve without excessive stress oor damage. If the valve and neck are properly machined, there will be full metal to metal contact between the valve and neck which then fully contains the neck o-ring.
Neck o-ring extrusion is not caused by a lubricant, but rather by 1) a valve that lacks sufficient metal or precision machining to fully mate with the neck to fully enclose the o-ring, or 2) an improperly tightened valve that is then loosened slightly in service creating a gap through which the o-ring can extrude. I've been able to loosen hand tight valves just by picking up a tank with as much 1200 psi in it. Valves need to be more than hand tight.
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A lubricant on the tank o-ring allows it to seat properly in the space between neck and valve without excessive stress oor damage. If the valve and neck are properly machined, there will be full metal to metal contact between the valve and neck which then fully contains the neck o-ring.
Neck o-ring extrusion is not caused by a lubricant, but rather by 1) a valve that lacks sufficient metal or precision machining to fully mate with the neck to fully enclose the o-ring, or 2) an improperly tightened valve that is then loosened slightly in service creating a gap through which the o-ring can extrude. I've been able to loosen hand tight valves just by picking up a tank with as much 1200 psi in it. Valves need to be more than hand tight.
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