Old air

[DA Aquamaster]

They were already galvanized, which is great news for rust prevention, but it is not the smoothest surface on which to apply paint. I wanted them to be yellow for a 58-59ish USD motif.

I am trying Krylon Fusion paint as it is cheap, easier than mixing Imron or something similar, and has been reported to hold up well.

We'll see.

 

[Couv]

I'm just getting used to my LP72s, and I have to say, it's too bad these tanks are not still made. What's not to like? They're small, lightweight, and neutral when empty.

What I would like to know is, what is the structural difference between the LP72, the current LP85, and the current X7 3442 PSI tanks? IOW, if someone today made a tank the same size and wall thickness of the LP72, could it have a 3000plus PSI service rating?

New paint on the tank and a new 3000psi burst disc (5000psi blow) and there you have it. But I thought you cave divers modified your burst disc with special "no blow" disc.

 

[halocline]

The ZRC site has a pdf bulletin about top coating over galvilite. The woman at ZRC that I spoke with (amazing to actually call a company and have someone answer the phone, and then answer my questions with clarity and authority) said that epoxy base paints are the best over their cold galvanized finish, and over any galvanized finish. She specifically said that lacquer and alkyd base paints would not stick, and that's why I was able to peel the paint right off of one of my 72s with no paint remover, just a putty knife.

My tanks were also galvanized, but it looked more like sprayed on galvanizing than the current hot dipped finish I see on modern tanks. The ZRC rep also said that applying the galvilite over the old galvanizing would work well and strengthen the galvanized protection.

DA, did you spray your tanks or use a roller? I ended up using spray cans of galvilite. I have a friend who is a real expert with a spray gun, but I just couldn't bother him for this job. The cans worked out fine, it took one for each cylinder with three light coats.

Here's the topcoating bulletin. I'm going to use galvilite with a topcoat for my Kidde bump-bottom.
http://www.zrcworldwide.com/pdfs/t_guide_topcoating.pdf

 

[rstofer]

Re: painting over the galvanizing, is there an issue with external tank inspection?

I'm afraid I don't know enough about the subject to properly ask the question. One attempt: is it possible for the paint to cover up or conceal corrosion?

The old LP 72 I have mentioned in this thread did pass hydro (with a '+'), VIP and is now O2 Clean. I'll pick it up on Monday. If I did want to remove decades of decals and paint the tank, what is the process?

I'm not sure I'm going to do this as I think I like to see the galvanizing but I could certainly change my mind if the process is relatively easy.

Richard

 

[halocline]

Do you mind me asking, how did you get the + rating, do you have the REE number, and who is the manufacturer and serial number of your tank? If your hydro guy has the REE number for 71-74 PST 3AA2250 tanks, I'd sure like to know it. So would a lot of other LP72 owners!

If your tank is galvanized and not painted, you can touch up the galvanizing with the galvilite if there are bare spots. If you want to paint over it I'm sure there are lots of threads floating around, and check out the ZRC pdf I linked to. I'm pretty certain that whatever recommendations they make for painting over galvilite apply to hot dipped galvanizing as well.

My old PST 72s really look more like the galvanizing was originally sprayed on as a primer. I wish I knew more about it.

 

[rstofer]

I don't have the tank in-hand just yet. I will look and see if there is a REE number and I'll try to chase it down. As to the '+' rating, I have that rating over-the-phone from the LDS that handled the service. I haven't seen it with my own eyeballs.

Richard

 

[rjack321]

Do you mind me asking, how did you get the + rating, do you have the REE number, and who is the manufacturer and serial number of your tank? If your hydro guy has the REE number for 71-74 PST 3AA2250 tanks, I'd sure like to know it. So would a lot of other LP72 owners!

72s are commonly plus rated without the REE number nor the impossible to non-destructively do wall stress calculations. Its not allowed per DOT, but gets done roughly 50% of the time around here though, "grandfathering" logic, ignorance, and/or laziness.

 

[halocline]

Richard, any news on your plus rating for the LP72? Did you get the REE number?

Personally, I find it a little unusual that a hydro facility would give a tank a + rating out of ignorance and/or laziness. Usually those are the things that keep a tank from getting one.

 

[rstofer]

I have eyeballs on the tank and I don't see a REE number but it is definitely '+' rated now. It was also '+' rated when it was initially hydro'd back in '77. Too complicated for me!

Richard

 

[Scared Silly]

rstofer, can you find out the name of the hydro shop your dive shop used.