Removing an epoxy lining

[Nemrod]

I will take any you want to trash as well as long as they have not actually FAILED a hydro. I too will pay shipping.
Steel 72 have good capacity, are neautrally bouyant and compact in size--a great tank.
If the coating is removed then they are like all steel tanks--no coating. The bare steel will flash rust, an oxide layer but so do all steel tanks. This does no harm--water etc in the tank however causes a more dangeous form of rust called pitting--this is destructive. The rust flash is not pitting and is normal. The epoxy coating were intened to stop pitting. Most places will not hydro or VIP lined tanks--right or wrong--that is how it is.
The lining can be removed by tumbling with the correct media, I have had it done several times but it is lengthy and today most places will not bother. Still--I would not trash those tanks---there are people who will take them. A steel tank has a virtually unlimited lifespan as long as it is kept properly. Some people have their own compressors and really could care ZIP about a VIP! (by anyone other than themselves)N

 

[Creed]

I will take any you want to trash as well as long as they have not actually FAILED a hydro. I too will pay shipping.
Steel 72 have good capacity, are neautrally bouyant and compact in size--a great tank.
If the coating is removed then they are like all steel tanks--no coating. The bare steel will flash rust, an oxide layer but so do all steel tanks. This does no harm--water etc in the tank however causes a more dangeous form of rust called pitting--this is destructive. The rust flash is not pitting and is normal. The epoxy coating were intened to stop pitting. Most places will not hydro or VIP lined tanks--right or wrong--that is how it is.
The lining can be removed by tumbling with the correct media, I have had it done several times but it is lengthy and today most places will not bother. Still--I would not trash those tanks---there are people who will take them. A steel tank has a virtually unlimited lifespan as long as it is kept properly. Some people have their own compressors and really could care ZIP about a VIP! (by anyone other than themselves)N

Do you recall what media works? Because, I can tumble this puppy for months if I feel the need.

 

[Bob3]

The ceramic media will cut the epoxy, but with the price of garden gongs topping a $100 it's hard not scrapping a perfectly good tank.
There are also strippers that will work, can't recall the name but if you can find something that'll eat the gel coat off fiberglass you're in luck.

 

[Nemrod]

No, it was done for me when I lived in Houston. The ceramic media sounds about right.
Everyone is so worried about this and that. Those steel tanks are so overbuilt a little bit of metal lost is no big deal. It will have to go to a hydro facility. It will come back with a new stamp on it and be good for years yet. New steel tanks run upwards of 300 dollars in some cases more. There really is no equivelent to the steel 72 which has nearly perfect neutral bouyancy, I wish there were because I would by one. The PST MP 72 is close but it has a much larger bouyancy change than the old steel LP 72s and that is really to bad. The aluminum 80s go from negative to several pounds positive as they empty, that is no good either. N

 

[DA Aquamaster]

The shop that did my tanks in the mid eighties used a crushed shell media. Definitely old tech compared to ceramic beads or chips but it did get the job done in about a week.

 

[FredT]

Steel beads (similar to what goes in a Claymore or BBs) will cut it if you have the tumbler speed right and have a bit of free fall in the media. So will used tungsten carbide turning bit inserts.

Daisy the airgun folks made the beads for the Claymore mines. You have to know someone in a major machine shop to get enough used bit inserts.

FT

 

[DA Aquamaster]

I like the steel BB idea. A bag or two of suitably sized steel shot from the local gun shop would probably work just as well I suspect but for less cash. Both would be made from relatively soft steel.

I have also heard of people using various nuts, bolts and washers from the local hardware store. But I think you need to be careful there as you want something signficantly harder than the epoxy but still softer than the tank itself.

 

[FredT]

Claymore beads are aobut 3/16 in diameter with a belt of about 1/4". The sharp edge of the belt would aid in liner removal.

 

[Creed]

And today folks, we have a lesson called buyer beware.

I took that steel 72 to my old instructor. He was going to do an informal VIP and let me know if he thought I should bother having it hydroed. Well, first off, the last hydro stamp appears to have been handmade. Immediately, warning bells are going off in my head. Secondly, the "epoxy" lining appears to be some sort of paint, like rustoleum. It flaked off upon contact with the inspection light. Someone actaully breathed out of that tank like that. Scary.
I immediately decided to junk the tank, but on the drive back home, I started to think that maybe it wasn't so bad after all. The paint should be easy to tumble out with just sand and water(and maybe some detergent). The question is, assuming that the last hydro stamp is faked, will the tank be "legal" if it passed a real hydro now?

 

[DA Aquamaster]

Not sure how you hand make a hydro test stamp. Most testers do a pretty good job of getting the numbers lined up. but if they did not, it would not make it any less vailid just less neat and less professional looking.

The critical stamp will be the small one between the month and year that would consist of the code for the test facility (normally a pair of letters above a pair of numbers). That code is on a single stamp, so any oddity in their relationship would suggest a forgery. If the code looks valid and you are still suspisious, you could contact the facility and provide them with the date and serial number of the tank and they should be able to confirm if the hydro was really done there. It would be a PITA for them to pull the test record, but they should still have it on file somewhere.

But more importantly, if the DOT numbers are not stamped out and the tank passes a new hydro test it should be legal and serviceable. One thing I saw recently on a tank was a set of numbers stamped on the side of the tank as someone apparently thought that was ok if there was not a convenient spot on the shoulder. Another tank had a name stamped in the side as a means of permanantly identifying their now totally useless tank as anything stamped in the wall of the tank is treated like any other gouge or damage and the tank is condemned if it is too deep.