Servicing tank valves and VI AL80s

[bobbyp10]

After wading through many previous posts that were very informative i got a lot of great information but am still unclear as to a couple of aspects of valve servicing and VI/tumbling for aluminium tanks.

Traditionally i was taught (albiet still very minimal experience) to remove the tank valve and dismantle it. No problem. Currently the valves are Thermos. Check the inside of the tank for cracked threads, pits, oxides etc.

Questions for discussion. I soak the metal tank valve parts in vinegar. This time i do not have any new synthetic white washers. Can i reuse the old ones? If so, how should they be cleaned, if at all?

The burst disc, any cleaning or straight back in?

Onto the tank. So after a careful inspection of the threads, body and neck all looks fine. I would normally tumble as a matter of course, at least for 10-15 mins even if all looked fine, longer if not so great (I have made a tumbler, works great). I do not have any of the cleaning fluid i would normally use. Which, if any, general purpose cleaner could i use to replace a recognised tank cleaner. I have started using glass beads for the tumbling, replacing ceramic ones i used before, on recommendation from a friend. Ok?

So, theres a few points to consider. It's all very well to say it'll probably be alright but i would rather get more accurate info before proceeding here.

Hope you can help a guy in a remote location. Any advice re valve servicing and tank VI and tumbling would be great!

 

[WD8CDH]

The Teflon washers can usually be re-used a few times with careful cleaning of the valve.

Don't reuse a burst disk. The process of removing it and replacing it will change it's burst pressure. It could be higher or it could be lower depending on how it seats and the torque that it sees. If it's a burst plug, it's not as effected but it should still be replaced because it may burst at a lower pressure from external corrosion on the disk.

I would NEVER tumble a tank if it didn't need it. Tumbling removes wall thickness however small so excessive tumbling will reduce tank life. It is especially bad to tumble an aluminum tank if it doesn't need it because tumbling will remove the thin protective oxide surface.

 

[captain]

I have found that if the teflon washers are cleaned with soap and water and reinstalled in the exact same position they will last indefinately.

 

[DA Aquamaster]

The oxide layer on an AL tank is essemtially self sealing and as such is protective of the underlying aluminum. So it is true that there is no advantage to tumbling the tank and removing it unless you need to. On the other hand, the oxide fairly quickly reforms, so you do not permanently lose the protection.

Now alclad aircraft aluminum is another matter. In that case, the protective layer is indeed protective and is designed to keep the surface nice and shiny without oxidizing and without frequent polishing. Once that layer is worn through the metal will quickly oxidize and look grey.

 

[jiveturkey]

Which, if any, general purpose cleaner could i use to replace a recognised tank cleaner.

Simple Green. You can use it on the valves too.

 

[Gilldiver]

Tumbling is done way too much, it should only be done if you see excessive corrosion that can not be removed with a whip or if there are deposits visible in the tank that a wash solution can not get off (heavy oil/tar from a poorly maintained compressor etc.).

I replace my over pressure assembly at the 5 year hydro test when the valve gets fully disassembled and cleaned. In most cases, all parts are reused with the exception of the copper bonnet gasket, o-rings, and the over pressure assembly.

If at the yearly visual contamination is found, the tank and valve will be cleaned.

What I have are 5 or 6 valves I have collected from dive shops over the years from condemned tanks. In February, I do my winter maintenance and will clean/rebuild any valves in need, then seal them into a Ziploc bag and put them on the shelf. During the year, I have these extra valves already rebuilt and clean so if I need one, the valve in question gets put into the rebuild bin and a clean rebuilt one put on.

For valve cleaning, I use a strong cascade dish washing solution in a 2 quart sauce pan. The valve parts are put in and everything is simmered at just below boiling for 10 minutes or so. Cascade passed the NASA testing for Oxygen cleaning for manned space craft.

For tank cleaning, I use simple green as there is enough smell to the solution so that you will know when it is fully rinsed off by your nose.

 

[bobbyp10]

Thanks to all those who contributed and gave great advice.
In the end, i found some local cleaning fluid that was as close to the simple green's description and used that. I tumbled one tank due to some oxidization using glass beads. Seemed to work ok. Valves went back together great. All tanks were filled with no dramas and air tastes fine.
Cheers for the help. I'm about to post a second query which you may be interseted in checking out....burst discs.

 

[Davidstealey3]

if you want, and also because it is cheep as hell, use joy dishwashing detergent. one bottle goes a long way, and is on the list for approved oxygen cleaning agents, not to mention easy to get at any grocery store.

use can use this for the valve also, so no need to keep two different cleaning solutions on hand.

 

[WD8CDH]

Curious, any other dish soaps or laundry soaps on the list?