Neck leaks

[gopbroek]

A friend (really) is having an ongoing issue with seeps (fine bubbles at pressure) at the tank neck / valve stem. The tanks (over 100) are by no means new and have anywhere from 1K to many K cycles on them and they are AL80's from multiple suppliers. The valves range from relatively new to multiple K cycles, again multiple suppliers from over the years, about half have been replaced with 'pro' valves from DGX over the last few years. The O-rings are buna 214 duro 90A (Sterling seal & supply via Amazon). For the few that I was present for when they were pulled apart I looked at the valve stem and O-ring and to me they looked in good shape. I suspect that the seeps are along oring to tank neck mating seat area.
Does this sound plausible and if so is there a standard method to smooth / clean this seat area, possibly a hone tool?
Any input or ideas would be appreciated.

 

[BRT]

One of my tanks in Mexico (heavily used by my friend) would not seal after an inspection. The shop tried everything. They had a tool to clean the surfaces, new o-rings, tried tightening it, multiple attempts. I finally took silicone grease and applied it to the o-ring, installed the valve with a tap of the heel of my hand and told them to fill it. The operator looked at me like I was stupid, and started putting in air and testing with soapy water to show me that it still leaked. He gave me a real funny look when there was no leak.

 

[Tracy]

XS Scuba Tank Tool - Aluminum Cylinder — XS Scuba - Everything For The Perfect Dive

For aluminum scuba cylinders only. Two tools in one: clean and true threads with 420 stainless steel chaser, and remove corrosion from O-ring gland. Replaceable adhesive backed sanding discs. Includes 10 sets of sanding discs.

www.xsscuba.com

 

[Gone for diving]

The O-rings are buna 214 duro 90A

I don't know what is spec,
But I use 70D orings.

 

[blue steal]

Gopbroek let us know if and how the issue is resolved.

 

[Scared Silly]

XS Scuba Tank Tool - Aluminum Cylinder — XS Scuba - Everything For The Perfect Dive

For aluminum scuba cylinders only. Two tools in one: clean and true threads with 420 stainless steel chaser, and remove corrosion from O-ring gland. Replaceable adhesive backed sanding discs. Includes 10 sets of sanding discs.

www.xsscuba.com

I can not remember if it was this tool or similar but I vaguely recall some issues as the sanding of the groove can remove material from the cylinder which would condemn it.

 

[Tracy]

I can not remember if it was this tool or similar but I vaguely recall some issues as the sanding of the groove can remove material from the cylinder which would condemn it.

It is supposed to remove material from the cylinder, that is how it works. That doesn't condemn a cylinder, it is normal maintenance.

 

[Scared Silly]

It is supposed to remove material from the cylinder, that is how it works. That doesn't condemn a cylinder, it is normal maintenance.

I had to go back and look it was different tool that I recall. I can not remember the other tool and what it did perhaps it was recutting the threads??? Just remember there were some implications.

 

[Tracy]

I had to go back and look it was different tool that I recall. I can not remember the other tool and what it did perhaps it was recutting the threads??? Just remember there were some implications.

I have another tool that cuts a new ring groove. I can't find it online, it is an old Peter built tool. I think he is out of business.

 

[broncobowsher]

It is supposed to remove material from the cylinder, that is how it works. That doesn't condemn a cylinder, it is normal maintenance.

I've seen that a lot in salty resort areas. Pretty normal maintenance.
There is a minimum thread count when doing a visual (I would have to check the book on what it is, but roughly 9 whole un-inturupted threads. Tanks typically have more than that. You would have to remove a LOT of material to remove a single thread. That tool isn't removing much material, you are not putting chips on the floor like you would cutting on a lathe. You are just dressing the top of the tank. Taking off the crust and maybe getting a thousandth of an inch into the material. Tanks are not that precise, look at the metal folds at the bottom of a tank neck. A little on the sealing surface is nothing. Maybe after 50 or 100 cleanings you might raise an eyebrow.