Rubber on tanks

[Phychotics]

Well i just picked up a steel 65 on ebay. Came in good condition, has some slight rust inside and hadnt been hydroed in a while. I was suprised at what little rust was in it. Its a luxfer and was manufactured in 1960...hehe that gave me a chuckle. Well i took it into my local dive shop, he VIP'd told me they could easily take care of the rust but told me i had to strip the tank....it was what looked like a blue rubber dip. he said they used to dip them instead od paint. But now they wouldnt hydro it because the steel can corrode under the rubber and eat a hole and they cant see it...so i set off for TWO WEEKS with a razor and stripped 90% of it off....i couldnt sandblast or anything etc becasue i couldt remove the galvanizing. So i get to the bottom of the tank which is of course rounded and cant get a good angle with the razor. So i trudge down to my hardware store and get some stripper....kinda a gel stuff. And in 15 minutes the stuff bubbled up and FELL off the bottom of the tank...i was sooo mad. I had just spent over 12 hours laborously stripping this tank,a nd then at the end i decide to get this stuff and it just falls off...just my luck. Its going to get hydroed in a few days. Has anyone ever experienced this runner stuff on tanks? r any other comments??

 

[DA Aquamaster]

I have stripped several over the years. Some are galvanized underneath and others are not. You are lucky that it is galvanized as it is a very enduring finish.

The lesson here is to ask first, as it would have saved you about 12 hours of work with a razor blade. Stripper is I think actually kinder to the galvanized finish than scraping with a razor.

In the early to mid 1970's they used an epoxy coating inside tanks and that is very difficult to remove, requiriung about a week to remove via tumbling and generally speaking you do not want to use a chemical stripper inside the tank.

 

[DennisW]

I have one that I am slowly removing the coating from the outside. Thankfully, it had not interior coating. Unfortunately, it is not galvenized under the rubber coating. The guy that hydro'd the tank did not have a problem with it at all. The tank is getting rusty on the outside under the coating and I remove a bit every year, but I never thought about using a paint stripper on the coating. Next trip is to the hardware store. Thanks for the information.

 

[Luis H]

In the early to mid 1970's they used an epoxy coating inside tanks and that is very difficult to remove, requiriung about a week to remove via tumbling and generally speaking you do not want to use a chemical stripper inside the tank.

Many dive shops will insist on removing interior coatings, but in reality you can easily inspect a cylinder with the coatings. There is no real requirement to remove the coating. In the PSI book “A Guide to Inspecting Cylinders” it even has a chapter on inspecting tanks with internal coatings and it clearly points out that the coating does not need to be removed.

I own three cylinders with white coatings and it is very easy to see if the coating has been compromised and if there is any rust. The coating is very smooth and any rust will lift it and is immediately obvious. Dark coatings are much harder to inspect due to the light and lack of good reflection from the coatings (I own one with a dark coating).

Tumbling (and even to some extent wire brush whipping) will remove the coating over any rust and the rust with it. The rest of the coating that is well adhered to the wall is much harder to remove and really not necessary to remove it.


I am not sure why they required removing an exterior coating over a galvanized finish. A very thick exterior coating can hide rust. But, if the tank was hot dipped galvanized it will not rust unless the galvanized finish is worn of…which seems impossible below a rubber or vinyl coating. Am I missing something here or is this just another LDS that lacks common sense?

 

[Phychotics]

Thanks for the imput fellas. Well since the tank was made in the 60's some little chips of rubber had been taken off...and so maybe that was the reason y some rust might get in. but to DennisW the Stripper is kind of a liquid gel stuff...it works so good the rubber/paint almost falls off itself....VERY little scraping needed. I was actually wiping with a papertowel and it came right off.

 

[oxyhacker]

Luxfer?

 

[Phychotics]

its actually a dacor