Unable to Remove Valve From Tank

[I Dive]

Who last put that valve on? You or a shop? If a shop did, and you still have the receipt, I'd take it back to them and ask them to show you how to take it off...

 

[Randy43068]

clamp it down and use a rubber mallet on the valve. It's already junk in this condition so what do you have to lose?

I'm assuming you can get the valve seat out so you and know for sure there is pressure in the bottle.

 

[DennisS]

Drop it off for a VIP

 

[Randy43068]

Drop it off for a VIP

it may be worth fifteen bucks to have someone else remove the valve.

 

[Teamcasa]

Fill the tank, then open the valve wide open to cool the metal (metal shrinks when frozen) then unscrew it while it's still cold.

This may work but wear ear protection.

Drop it off for a VIP

This will work...


Or,

Tank vise and a good long pipe wrench. Heat the tank neck with a heat gun. The valve will be shredded but it will come off or break, one way or the other you will want a new valve.

I would not use any lubricants.

 

[Leadking]

When installing a valve in an aluminum cylinder ALWAYS use Dow Corning 111 to prevent seizing and galling. You can actually tear the threads out of an aluminum cylinder by using brute force.

 

[Randy43068]

When installing a valve in an aluminum cylinder ALWAYS use Dow Corning 111 to prevent seizing and galling. You can actually tear the threads out of an aluminum cylinder by using brute force.

I hear you, but it's been my experience that those AL tanks with lubed threads were the toughest to take the valve off. Sounds funny, but that's my experience. I never use the stuff anymore.

 

[DA Aquamaster]

I always lubricate the threads when putting a valve in an AL tank - but I use Christolube, not a silicone (petroleum based) lube. If you do not use some type of lubricant, any moisture at all in the tank can promote dissimilar metal corrosion in areas where the chrome plating on the valve has been compromised and it will cause problems.

For similar reasons, one thing I do NOT do is torque the valve to the specified 75 ft pounds. Just a bit beyond hand tight is all that is really needed, and 75 ft pounds without lubricating the threads can cause issues with galled threads and corrosion.

At this point, you can probably remove it with a chop saw as the tank itself most likely has damaged threads and is now about 30 pounds of scrap aluminum.

Someone suggested heating the tank with a heat gun. That's fine as long as you recognize the tank will also be scrap. Any portion of the tank heated over about 325 degrees F will lose its heat treatment and be too soft to safely hold air.

What I would do is take it back to whoever put the valve in and say "remove it". Then absent evidence that water was in the tank and caused corrosion, I'd say "replace it" after they damage the tank removing the valve. Of course you get more traction with that approach when you do it before you have made any excessive and/or obvious efforts to remove the valve.

 

[Teamcasa]

Tank vise and a good long pipe wrench. Heat the tank neck with a heat gun. The valve will be shredded but it will come off or break, one way or the other you will want a new valve.

Someone suggested heating the tank with a heat gun. That's fine as long as you recognize the tank will also be scrap. Any portion of the tank heated over about 325 degrees F will lose its heat treatment and be too soft to safely hold air.

The momentary and direct heating of an aluminum (as the OP stated) scuba cylinder will not change the physical properties of aluminum unless the gun was allowed to spend a very long time in one spot. Aluminum conducts heat very well and the heat would dissipate quite quickly.

In the case of a seized valve, if it can not be removed, even after heating the neck is scrap anyway.

 

[Randy43068]

Dave, that's what I'm saying, too. Not much to lose as I see it.