Vintage Double Hose

Hi,
Has only any of our members ever successfully tumbled this blue interior coating out a tank.
I'm using aluminum oxide chips (14 hours tumbled) cannot remove.
This is the worst coating Udivers ever put in a tank,I have removed many coatings never had one like this.
Thanks,Glad everyone had a great time in the Bahamas!
Jerry

Give it up . . I have tumbled them for days and not so much as a clean space. It seems to be some kind of rubberized epoxy coating.

This might be a really stupid idea, but what about some sort of solvent to wash it out, then tumble to remove any trace of the solvent? There's got to be something that will dissolve the plastic coating.

Jerry, the hydro shop I use has no problem with lined cylinders.

Ditto with Captain. Come dive in the St. Lawrence or Finger Lakes with me and we'll get that puppy hydroed.

Anything that will dissovle the plastic coating is potentially also going to oxidize the steel.

I also just had a lined tank hydroed with no problem. As long as you use them with air or premixed NITROX there should be no problems. I don't like to do pure O2 in a lined tank, I have done it but don't make a practice of it. If you ever wanted to do a pp fill, stay below 350 psi (320 psi in a 2250 psi tank will get you 32%) and fill real slow.

I have never tried to get the resin out, but I have seen photos of steel shot blasting systems for 200 and 300 cubic foot welding tanks. It should work on the resin. You could also try a paint stripper with methylene chloride, if the resin is an organic, methylene chloride should eat it over time.

If anyone wants to try with a scrap tank that is cut open try some stripper and see if the coating will loosen, bubble, or soften- try this outside only.

If the stripper works, put in a pint or so of stripper into a good tank, put a valve back on, roll it around to coat the entire surface and let it sit in a warm area for an hour or so. Pour out what you can, then rinse with hot water. Immediately add a rough tumble media and start tumbling. If the coating is soften enough, the media should now be able to cut it.

The problem with this, is that it creates a lot of hazardous waste and is more work then I would ever want to do. Steel 72’s are common and it would be easier (and cheaper) to just find another tank.

A last alternative would be a commercial hot paint strip firm. There are not all that many left, but if there is one near you, a hot phenol based stripper will eat anything.

Hi,
Thanks for the tips the coating is loose.
I have been tumbling tanks since 1973 yes 1973 and this is the first lining I cannot get out.

There was an article in Skin diver magazine about a technique do it yourself using paint
stripper etc.I'm looking at my collection and maybe can find it.

I'm not gibving up on this tank and will not breathe air from it if dangerous toxic chemicals are needed to strip it out.
Happy Easter to all espically Rob and Esther Williams

I was talking to another diver about the old 72's today and the internal resin coating came up. He very off hand said that another diver had come up with a way to tumbled it out. This diver used 3 pounds of stainless steel dry wall screws as the tumbled/cutting media. Still takes a few hours but it was claimed to get all the resin out.

Pete Johnson

screws?

I would never have thought of it, but the screws are sharp and would help cut the resin.

I might follow up with a standard tumble with regular media to smooth out and micro cuts in the steel.

Hi,
I finally remvced all that interior coasting using aircraft stripper,then tumbling rinsing etc.
The Blue coating is the absolute worst and strongest coating Usdivers used.
The white and brown coating can be tumbled out in three or four hours with aluminum oxide chips from Globel.
This tank was really alot of work,the nice thing is that its galvaniz ed under the yellow vinyl coating.

Jerry