Tank maintenance and rust

[doctormike]

OK, I really can't find the answer to this online, and the dive shops that I called don't do this work either.

I have these Asahi tanks, steel 120s, that I got used last year. I do like the weight characteristics, but I don't think that I was that good about maintenance. I probably let them dry without a good rinse, and without taking off the boot and removing retained water, etc... This picture is from before last season, before they started to rust on the sides.

They are painted, not galvanized. I think at some point I will replace them with galvanized 100s that I might double up, but that is not for a while.

Right now there is a good bit of rust on them, mostly on the bottom, but a bit on the sides. I was planning on trying to fix this myself, and need some advice.

I was going to take a steel brush drill attachment and/or steel wool and get rid of the rust. Do I need to completely remove all of the old paint? Do I need primer? Marine paint? Or just take off some of the rust and try to be better about rinsing and drying them after diving...

OR, are there companies that do this sort of job the right way? I'm in the NYC area...

Any suggestions would be most appreciated!

Thanks,

Mike

 

[elmer fudd]

What I do is remove the boots and look for any bubbling in the paint. If I see it, I get out a screw driver or chisel and scrape it off until I'm past all the damaged paint. Then I use a wire wheel to bring that spot down to bare metal and paint over it with Rustoleum, Duracoat or whatever I happen to have that matches the tank. When everything is dry, I'll often put the boot back on again.

After using the tank, I remove the boot rinse it with water, then rinse it again while rubbing the tank with my hand. I also rinse off the boot inside and out. This is just part of my normal gear cleanup and it only takes about a minute, since I'm rinsing everything else off at the same time. While doing the rinse, I inspect it for rust.

With a modern galvanized tank and modern boots, I only remove the boot occasionally.

I don't worry too much about light surface rust. Pits are what concern me. The worst tanks for this in my experience are the old vinyl coated LP tanks from the 70's. Water can get under that coating and migrate. I bought an old pair of 50's a couple months ago. One had a boot and one didn't. Both looked fine on the outside, but when I got that boot off and started scraping off the vinyl coating underneath, flakes of rust the size and thickness of silver dollars came off with it. The other tank was fine and if the weather improves I might dive it later today.

 

[spectrum]

My biggest concern is what might be under that boot. It looks like the full contact type that accumulates salt and holds moisture. Remove the boot and remove rust as needed then prime bare metal with a cold galvanizing finish. Finish as you wish with a good enamel or leave primed. After all that get a self draining (Underwater Kinetics) boot.

Pete

 

[doctormike]

Thanks so much, I really appreciate the advice..!

So I don't need to strip off all of the paint, I can just pain over the old paint, right? (if I use that cold galvanizing spray)

The boot is self draining, as far as I can tell. But maybe I'll get some of those Underwater Kinetics boots to be on the safe side...

Thanks again!

Mike

 

[rjack321]

how much rust are we talking about here? any current pictures?

 

[doctormike]

how much rust are we talking about here? any current pictures?

Not that much... I'll take a picture and post it, but I dropped them off to get filled and I won't pick them up before the weekend...

M

 

[captain]

The cold galvanize has to be in contact with bare metal, it doesn't work well over paint so only the areas where the paint is removed need the cold galvanize. You can top coat over it and the old paint.

 

[doctormike]

The cold galvanize has to be in contact with bare metal, it doesn't work well over paint so only the areas where the paint is removed need the cold galvanize. You can top coat over it and the old paint.

OK, thanks!

 

[elmer fudd]

Stripping the tank down to bare metal and refinishing with cold galvanizing finish is best, but it's a lot of work. You can buy spray cans of galvanizing paint at the hardware store, but they only give a very thin coat. To get the good stuff you'll likely have to order it.

The original paint on the tanks seems to be pretty tough and so long as it's intact it does a good job of protecting the metal. Hardware store enamel isn't tough at all. It will scrape off with normal use, but I find that most of the time it's adequate to cover a handful of dime sized scrapes for a year or so and prevent rust from spreading. You can give the spots a quick spray of auto primer as well.

 

[doctormike]

Stripping the tank down to bare metal and refinishing with cold galvanizing finish is best, but it's a lot of work. You can buy spray cans of galvanizing paint at the hardware store, but they only give a very thin coat. To get the good stuff you'll likely have to order it.

The original paint on the tanks seems to be pretty tough and so long as it's intact it does a good job of protecting the metal. Hardware store enamel isn't tough at all. It will scrape off with normal use, but I find that most of the time it's adequate to cover a handful of dime sized scrapes for a year or so and prevent rust from spreading. You can give the spots a quick spray of auto primer as well.

Gotcha, thanks! Do I need to empty the tanks before working on the outside?