Old tank warning

[jjeff1]

I'm sure this has been discussed, but I wanted to add my own 2 cents.

My dad got his certification in 1968 and accumulated various equipment over the years. Life got busy and several tanks sat unused from the early 1970s till 1995, when I got my cert. The tanks were tested and passed all the proper inspections. Fast forward to this year, when I decided to start diving again after a 15 year break. I took in my 3 steel tanks for testing. One passed, the 2nd failed visual, and I didn't even bother testing the third, due to the attached picture. The rust area is the size of a silver dollar and was under the boot, which is why I never noticed.

This tank has been sitting, dry, in a basement, for 15 years, with 1500 PSI in it. I figure the last time it was used, water was forced in between the paint and metal, and sat there, eating away at the tank. The rust area still seemed to be rusting away, it didn't have the look of old surface rust. So I assume at some point the tank would have failed, with destructive results.

Point being, if you have old tanks, do what you're supposed to, let out all the air except maybe 100 PSI.

Jeff

 

[k ellis]

Yikes. Thankfully you decided to get them tested when you did.

 

[halocline]

What does your rust spot have to do with letting most of the air out of the tank? Are you concerned that someone would cause an explosion by storing a full tank, which would then slowly corrode to the point at which it blows up? I think that's near an impossibility; much more likely would be some eventual leak which would allow the air to escape, probably in the neck o-ring, valve, etc....

 

[Jim Lapenta]

A good reason to not use boots if the tank is going to sit for any length of time. At least you have the makings of one sweet windchime!

 

[Wookie]

Maybe it's poor photography, and lord knows I don't inspect cylinders from 1500 miles away, but that cylinder looks fine to me. Little Ospho on a rag, take it to the hydro tester, some rustoleum safety yellow, and go diving. I've seen brand new cylinders right out of the box that don't look that good.

But maybe it's just poor photography, or a trick of the light.

 

[spectrum]

Those old clingy vinyl /rubber boots were evil. They would hold water & salt for a prolonged period. If there was any blemish in the finish corrosion had a feild day. I have a few with similar damage. One is beyond consideration.

The newer self draining Underwater Kineticks boots only have radius to radius contact so moisture can't be retained. Regular rinsing or soaking and periodic removal to clean any accumulated salts should be all that's needed.

Also beware of any boot that lets the base of the cylinder touch the floor. Those will soon result in finish blemishes that permit corrosion.

Wookie you may be on to something. Remember that rust causes "metal growth" so all of what you see is not pit depth. A quick hit with a sandblaster, cold galvanize and yellow touch-up may make all well.

Pete

 

[Gilldiver]

That looks like one of the un-galvanized steels that were made between 69 and about 72. The idea was that a vinyl coating was better and cheaper than the galvanizing. Time proved this not to be and I have seen much, much worse. I have a 1960 galvanized steel 72 that has lived its last 51 years with a boot that is pristine.

 

[captain]

As Gillman said that was a vinyl coated tank, not painted and water could work it's way under the vinyl from a small cut or scrape, boot or no boot probably wouldn't have made a difference in that case. The vinyl can be scraped off and the rusty area wire brushed and it may or may not pass re-qualification. If it passes paint it with some ZRC Galvilite.
It could and most likely was in that condition before it was put away in 1970.

 

[Paladin]

I have a 1976 Healthways (Norton) 72 that has a vinyl coat over galvanized steel. It's in pretty much the same condition now as it was the day I bought it new. Too bad all those vinyl-coated tanks weren't made to the same specs.

 

[LeadTurn_SD]

I'll add one more vote to have the "rusty one" tested before automatically tossing it out.

Hard to tell from that photo, but I'll add another "I've seen worse" tanks that were actually ok... they had been stored with air inside, had some ugly rust outside but were ok internally, passed hydro, and cleaned-up nicely.

Best wishes.