Buying 72s when you can't inspect them

[mwilding]

Any advice on buying old 72s when you can't inspect them in person prior to the sale?

I read every post in about 6 pages of threads on 72's and have figured out this much:

I want to get 3/4" threads not 1/2" threads
Galvanized are better than painted
"Yellow" tanks are especially bad (mentioned several times but not sure why)
Getting a "+" hydro is desirable
ZRC is the best cold galvanizing finish
Roman Guzik can custom make bands cheap for any manifold


Anyone know a guide to deciphering tank markings on these older tanks?
If the tanks come painted but have a current viz & hydro is it worth stripping and cold galvanizing them right away?
Would this make another viz a requirement?
Anything else I should consider?

 

[mwilding]

note - inability to inspect is factored into the price I will pay

 

[COVCI]

The fact that yellow cylinders has been mentioned several times may be because PST did quite a run of steel cylinders that were coated on the exterior with an epoxy coating. Some were galvanized beneath the coating, some were not. The cylinders that were not galvanized prior to the epoxy coating, should be removed from service, because there is no way of doing a proper inspection for corrosion.

Best way to tell you may ask...scrape some of the epoxy coating off. Expose area to moisture. Did it oxidize? Then it does not have the galvanize finish. Also...some cylinders actually have "galv" stamped into the crown indicating the galvanize finish.

I will be more than happy to try to determine stampings if you want to post them here, show a photo, or send by email.

Hope this helps,

Chris
COVCI

 

[FredT]

Neither is 1/2" NGT (taper) threads.

On ANY epoxied or painted tank inspect the second hydro stamp date and top fothe tank next tothe vlave looking for corrosion around the edges.

If no corrosion there is a good bet the tank is OK. Ungalvanized tanks tended to do bad things around the hydro stamp and valve. Also the hydro shops typically removed a bit of the coating to do the stamps. Check this area for traces of galvanizing, and also any spot on the tank that has a loose "chip" in the epoxy. the bottom of the chip will be red on ungalvanized tanks, generally it'll be white on a galvanized one.


For SCUBA use the 3/4-14 threads of a modern valve are what you want, but the tapered valve tanks are readily and cheaply convertable to a boat safe emergency O2 tank. Don't pass them up "just because" if the price is right.

BTW IMNSHO ANY tank that the owner refuses to allow me to inspect internally has the price I'll pay drop directly to the value of the valve, unless I need another garden gong.

FT

 

[pescador775]

Not more than six months ago, one of those yellow USD tanks exploded and blew some poor Mexican's car to the next block.

All those yellow USD tanks made in the sixties and early 70's are junk. Stay away from them. I say this because you have already stated that you cannot inspect the tanks personally. (If you do, pull the boot in addition to other recommendations).

If you can't inspect then you must ask questions concerning the obvious, like hydro and internal inspections but also about internal coatings (bad).

If you can find out nothing else, look for a galvanized tank with the PST stamp and an original date later than 1976. If the tank is marked 'Scubapro', buy it regardless of year. All their 72 cf, 2250 tanks were 3/4", galvo, with no internal coating.

1/2" tanks are OK but a pain in the ass for the newbie and the shop unless they have the right tools and knowledge.

Pesky