Remove ext. coating

[hydro212]

I have an old steel 72 that has a thick yellow coating on the outside. It isn't hard, more like plastic and very durable. It does a great job of protecting the tank but I want to get it off. Scraping/sanding would take about 100 hours of work.

Can it be sand blasted? If so, who could do it? If it can't be sand blasted, how can I get it off?

 

[COVCI]

While I have never sandblasted or blasted with any other media, I have removed this coating by cutting it off. Scoring the material and scraping it off until it was removed.

Any blasting technique used should be careful not to remove any metal from the surface of the cylinder.

Good luck,

Chris

 

[mike_s]

I have an old steel 72 that has a thick yellow coating on the outside. It isn't hard, more like plastic and very durable. It does a great job of protecting the tank but I want to get it off. Scraping/sanding would take about 100 hours of work.

Can it be sand blasted? If so, who could do it? If it can't be sand blasted, how can I get it off?

I would say by the time you had it sand blasted and then hydro tested, which will also require the tank to be cleaned and a VIP, that a steele 72 isn't worth it. The reason I said hydro tested is because you don't know if sand blasting will hurt the pressure strength of the tank.

My advice, which may not be worth much since I've never done this, would be to either do nothing to it or use the funds towards a larger and higher PSI tank like an aluminum 80.

What's so bad about it that you want to get the coating off? (besides being banged up or scratched).

-mike

 

[COVCI]

What's so bad about it that you want to get the coating off? (besides being banged up or scratched).

-mike

is that if the cylinder is not galvanized underneath the coating, the surface is obscured to the point that a true visual inspection is not possible.

Ungalvanized surfaces under an external coating that has been compromised can easily be corroded to the point of catastrophic failure.

Hope this helps.

Chris

 

[mike_s]

is that if the cylinder is not galvanized underneath the coating, the surface is obscured to the point that a true visual inspection is not possible.

Ungalvanized surfaces under an external coating that has been compromised can easily be corroded to the point of catastrophic failure.

Hope this helps.

Chris

Good point. Don't know why I didn't think of that earlier as that's one of the reasons I've never put that full size tank stickers on any of my tanks. (you know, the ones that look like logos and are huge decals).

 

[hydro212]

COVCI, I tried scraping some of it off and not only was it very difficult but it did not come cleanly off of the tank. Did you have a special technique or tool when you did it?

 

[teknitroxdiver]

I've never seen this kind of coating, but judging from your description of it, it sounds like you can take a very sharp knife and cut the coating from the neck, all the way down across the bottom, and back up to the neck on the other side. The get a stiff putty knife or something similar under it and slowly work it off. Of course, I've never seen it before so that may not be practical.

 

[Nemrod]

The coating is a very hard epoxy materail. I have a few tanks from USD circa late 60s. The ones I have are galvanized below the coating.

"My advice, which may not be worth much since I've never done this, would be to either do nothing to it or use the funds towards a larger and higher PSI tank like an aluminum 80."

Well, if you want another tank I would not make it an aluminum 80, while popular they are life limited, are very positive bouyant when near empty and not all that great a tank for diving. The newer so called neutral bouyant 80s maybe a better choice but I have never gotten to use one. I have several aluminum 80s. A few of them are from the early 80s--Luxfer--for Dacor --and I understand some of these have structural issues around the neck and shoulder. A good steel 72 is worth saving if you can reasonably do so. N

 

[COVCI]

COVCI, I tried scraping some of it off and not only was it very difficult but it did not come cleanly off of the tank. Did you have a special technique or tool when you did it?

years of exposure to UV and the elements. That was the only reason for actually taking the time to cut/score the material and then scrape. The cylinders were in a condition that made it worth while. Others I have seen are barely worth discussing, much less taking the time to remove the exterior coating.

Let's face it....liners whether inside or outside the cylinder are a PITA. The idea is not an effective one or else we would be talking about how to remove them. No current manufacturer of SCUBA cylinders would consider using one today. So...as stated before, cylinders are relatively inexpensive for the amount of years of service we get from them.

If your time/effort is more valuable than a few bucks, get a new cylinder and turn this one into a discussion piece.

Chris

 

[DA Aquamaster]

Any decent paint stripper will remove the coating with minimal scraping and while I am very cautious with the stripper I use on AL tanks, it really is not an issue with steel tanks. Just get a can of zip strip or similar stripper and have at it.

Scraping can damage the galvanized coating underneath, where as the stripper won't. If it is not galvanized, just rinse it thoroughly, dry it, prime it and paint it.

Don't fret about the teeming and largely ignorant hordes who indicate a steel 72 is not worth the time or effort to strip. The bouyancy traits are much better than an AL 80 and it will probably outlast them all.