Tank Saver?!?! Is thing for real?

[oxyhacker]

Not void the hydro, void the tank! A hydro doesn't automatically make everything well again. There are many things that can be done to a tank that will render it DOT-illegal, regardless if the tank is rehydroed. Any procedure that removes a more than trivial amount of metal is considered a modification. Doing anything that might weaken the neck is especially questionable, as that is the prime troublespot on aluminum tanks.

But then we divers are not as concerned with what is legal according to the exact letter of the law, but rather with what is likely to cause hassles for us down the road when we try to get the tank filled. And freshly machined tank top on a very old tank is the sort of thing that attracts questions from fill stations.

The fact that Luxfer says using the tool would be grounds to condemn the tank is enough to make me avoid it. If pitting is preventing the valve from seating flush against the tank top some careful filing to remove just the high spots as suggested by Beano should do the trick without making is so obvious that the neck has been worked on.

Good answer oxyhacker. The fact that some of the metal is removed is enough to void the hydro. If however a new hydro was undertaken and it passed, I wouldn't see a problem in using it.

 

[DCBC]

DOT's Regulations pertaining to compressed gas cylinders mainly address markings and shipping. They also touch on handling and testing, but the testing regs are limited to hydrostatic requirements. What "legal requirements" are you referring to oxyhacker?

 

[mongodives]

I'm guessing Oxyhacker is confusing/mixing legal standards with industry/manufacturer standards.

 

[fppf]

Who cares if they make the tank void or not, they are not refinishing the sealing surface. The oring should never be in contact with the TOP of the tank neck. It seals on the ID of the tank neck to the bottom of the valve.

 

[Texfrazer]

I'm guessing Oxyhacker is confusing/mixing legal standards with industry/manufacturer standards.

Well, DOT regulations prohibit any type of rethreading unless performed by the manufacturer, under the observation of an independent inspection agency. And, all DOT 3 cylinders may only be rethreaded once, and the tank has to be stamped as such.

Using a tool to carve away part of the neck could be interpreted as a partial rethread (or it might not, depending upon which lawyer you talk with ).

Therefore, it is quite possible that using the tool could be grounds for violating DOT regulations.

 

[Randy43068]

Who cares if they make the tank void or not, they are not refinishing the sealing surface. The oring should never be in contact with the TOP of the tank neck. It seals on the ID of the tank neck to the bottom of the valve.

True, but if pitting on the top surface is preventing the valve from being threaded down far enough to allow the O-ring to do it's job, then taking a little off the top of the tank will let the valve down a little more to crush the O-ring just a little more.

That's my take on it.

 

[Randy43068]

Well, DOT regulations prohibit any type of rethreading unless performed by the manufacturer, under the observation of an independent inspection agency. And, all DOT 3 cylinders may only be rethreaded once, and the tank has to be stamped as such.

Using a tool to carve away part of the neck could be interpreted as a partial rethread (or it might not, depending upon which lawyer you talk with ).

Therefore, it is quite possible that using the tool could be grounds for violating DOT regulations.

Re-threading a tank neck was all I can recall from my PSI training as being forbidden. I should go look it up.

 

[fppf]

True, but if pitting on the top surface is preventing the valve from being threaded down far enough to allow the O-ring to do it's job, then taking a little off the top of the tank will let the valve down a little more to crush the O-ring just a little more.

That's my take on it.

Pitting makes a depression, not a raised surface, it should not stop the valve from bottoming when torque.

 

[Randy43068]

Pitting makes a depression, not a raised surface, it should not stop the valve from bottoming when torque.

I think it's pretty worthless too, but just saying that if one takes a little off the top then the o-ring compresses a bit more. I think filing it is a piss poor idea because if you let a trough, or gap between the valve face and the neck top then the O-ring has a really, REALLY good chance of extruding.

 

[krulle]

Pitting makes a depression, not a raised surface, it should not stop the valve from bottoming when torque.

that's true, and pitting is only occuring in dynamic situations.

Does anyone know the real degrading-mechanism that affects aluminum bottles?