Painting Steel Tanks

[NeedABiggerBoat]

I'm looking to buy a pair of HP 80's for a doubles rig, but want them painted black. Can anyone share advise on type and supplier of paint, application, tips, ect. Your help is much appriciated.


P.S. Why do low pressure steel tanks weigh more than high pressure ones. In my mind I would think the high pressure tank should weigh more, more pressure: more steel to retain that pressure. Whats the story?

 

[SparticleBrane]

For starters -- why HP80s for doubles? For that matter, with <50 dives according to your profile...why doubles at all? Work on your basic skills -- buoyancy, trim, etc. Get comfortable in the water before you move to doubles.

Double HP80s will put you on your head unless you are about 5ft tall or shorter.
Painting steel cylinders isn't necessarily the brightest idea, unless you happen to be the factory. If they are PST or Worthington they are most likely hot-dipped galvanized, which is the best rust protection for steel tanks available. Faber usually has white cylinders and their finish is high quality but I don't believe it protects from rust quite as well as the hot-dipped finish of PST and Worthington.

I suppose you COULD paint the cylinders, but it wouldn't look good, and would only serve to hide any possible corrosion that might be on the cylinders.


As to the weight difference:
Are you speaking of comparable volume cylinders, or comparable cf-rated cylinders?
LP80s are heavier than HP80s because LP80s have to be larger to hold 80cf at a lower rated pressure...does this answer your question?

 

[matt_w]

The weight difference also depends on what models of tanks you are comparing. Faber HP-80s are heavier than Faber LP-80s while the FXs weigh less. The problem with HP80s is they are 5" shorter than any other tank people would use for doubles. Most people will be very head down with that configuration unless they put the backplate so low they can not reach the valves. (Not a good idea).

HP80s are 19-20" long and LP80s are about 24-26" long. It may not sound like much, but most people would find the constant head down "pressure" uncomfortable (unless they were pretty short). In someone inexperienced, it could be dangerous. Not sure about paint, questions are usually about how to get paint off of steel tanks.

I'm looking to buy a pair of HP 80's for a doubles rig, but want them painted black. Can anyone share advise on type and supplier of paint, application, tips, ect. Your help is much appriciated.


P.S. Why do low pressure steel tanks weigh more than high pressure ones. In my mind I would think the high pressure tank should weigh more, more pressure: more steel to retain that pressure. Whats the story?

 

[scubapro50]

I have painted several steel tanks over the past few years. The best tanks to paint are used galvanized ones in excellent shape. You should clean the outside of the tank and make sure there is no dirt or sticker resdue on them (DO NOT SAND THEM because this will destroy the galvanize coating and cause problems). Use a good epoxy spray and apply in several coats evenly without using a primer. DO NOT BAKE THE CYLINDERS ...... some people have tried this at auto repair shops that use ovens with explosive results ..... the high heat will cause damage to the tanks. I have painted several 71.2 cu. ft. tanks in the last few years so they will show up better in underwater photos. I love using bright yellow, red or royal blue. You can find large tank decals from companies such as U.S. Divers, Voit, Dacor, Swimaster and others to apply to the tank for a great look on Ebay. The painted tanks will get scraped and will peel over time but if you keep some of the spray paint you can always touch them up as needed.

 

[Eric Sedletzky]

I've been in the painting business all my life. I've worked in body shops, painted large commercial equipment, did marine work - steel- stainless- aluminum, worked with fiberglass, almost everythig.
To do steel right takes several steps. On steel boats we used to sand blast the steel until it was completely clean. They call this white steel. Then a zinc rich epoxy primer gets sprayed on followed by an epoxy barrier coat primer followed by a final finish usually Awl Grip, Sterlings, or Imron. This is the commercial way to protect steel. By the time you find and buy all this stuff plus the equipment to apply it you could probably buy any steel tank new for less money.

My suggestion is to wire brush any rusted spots the best you can and apply some cold galvinizing compound to the exposed areas. This would be for a previously galvanized tank.

If it's a painted tank then sand off any rust and feather back the area where you broke through. Then treat the cleaned up rusted areas with a little naval jelly(read the directions). After you rinsed the treated areas thoroughly (you can not have any naval jelly residue left on the steel or nothing will stick to it) towel them real quick and blow them dry. Don't leave them wet too long or they'll re-rust. A little yellowish haze on the bare steel is OK. Spot prime the exposed areas with rustoleum zinc rich primer (2 coats) then proceed with painting the rest of the tank with a better quality rattle can like rustoleum's commercial grade, 3 coats.

Forgot to mention, before you prime or paint, prep the tank with 320 grit sand paper then go over it with a red scotch brite and make sure the whole thing is dull so the new paint will stick. This rattle can method is not the best or the fanciest, but it is economical and it will last a while.

If you have a DA sander it makes the whole thing a lot easier.

Note: On a galvanized tank DO NOT use naval jelly or any other phosphoric acid solution to kill the rust. This stuff will destroy galvanizing and turn it black. Just clean the rust up the best you can by picking at it, usinfg wire brushes, wire brush on a drill, and trying to get out as much as possible. Avoid using a grinder becase you can remove too much material too quickly.

 

[chrpai]

ZKY ( and others ),

I know this is an old thread but you really know your stuff. I just got a used steel lp95 that's factory painted white. It has some spots that are bare metal and/or surface rust. It also has some spots that look like they have been touched up with white primer.

This tank will only see fresh water and never salt water if that matters to you.

If I'm not worried about appearance per say. What are the steps, if any, that I should take to protect the tank from additional corrosion?