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Post by nikeajax on Sept 9, 2018 15:53:10 GMT -8
Curious, how did this work out? I have an old set of 50's with plastic coated outsides and a white inner liner. They are out of hydro and I'm thinking of bringing them in. I'd like to know how the shop reacted to the lining. Honestly, take them to a fire extinguisher testing fascility!!!! Too many shops aren't familliar with old gear and they will fail them without even testing them: there is nothing wrong with vinyl coated tanks, but there are lots of myths about them JB
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jviss
Pro Diver
Posts: 209
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Post by jviss on Sept 9, 2018 16:59:21 GMT -8
That's a good idea, thanks. I have already sent inquiries to a couple of commercial cylinder testing facilities. The two local dive shops want $30 or $60 per cylinder. What kind of prices are you seeing?
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Post by nikeajax on Sept 9, 2018 17:44:26 GMT -8
Here in the Oakland metro area, I believe it was $15 per hydro and $5 to tumble at Acme Fire Extinguisher. They don't do a viz sticker though...
JB
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Post by SeaRat on Sept 9, 2018 18:10:54 GMT -8
Curious, how did this work out? I have an old set of 50's with plastic coated outsides and a white inner liner. They are out of hydro and I'm thinking of bringing them in. I'd like to know how the shop reacted to the lining. Honestly, take them to a fire extinguisher testing fascility!!!! Too many shops aren't familliar with old gear and they will fail them without even testing them: there is nothing wrong with vinyl coated tanks, but there are lots of myths about them JB Jaybird, I was in charge of the scuba locker at the 304th Aerospace Rescue and Recovery Squadron (ARRSq) at Portland, Oregon in the 1970s. I also worked with the scuba locker of the 33rd ARRSq at Naha, Okinawa. What we found was that the vinyl-coated tanks were fine as long as the vinyl was intact. But if it was nicked through to the metal, there were problems. The problems were that the steel was not galvanized, and therefore subject to corrosion. It was difficult to adequately wash out the salt water after diving, and these nicks could corrode severely the unprotected steel. This is for the outside coating. This photo shows how these vinyl-coated tanks can get nicked very easily. Note that this is on sand, but that there are rocks intermixed within the sand. The inside coating is a different situation. As long as salt water doesn't get inside, there should be no problem. But if salt water gets inside, and there is even a small nick, or a portion of the liner that has lifted off the steel, there will be a corrosion problem. The way to prevent this is not to allow these tanks with internal vinyl liners to ever empty. If they are empty, and the valve is allowed to stay open, especially in a very humid environment like Okinawa, there could very well be corrosion inside. John
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jviss
Pro Diver
Posts: 209
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Post by jviss on Sept 9, 2018 18:45:46 GMT -8
Thanks. Mine are vinyl coated, and there are nicks with corrosion showing. Should the vinyl be stripped off of these? I had contemplated that at one time, and bought a can of ZRC Galvinite galvanizing compound to coat them after vinyl and rust removal.
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Post by nikeajax on Sept 9, 2018 20:48:37 GMT -8
Yes, by all means, remove the vinyl from the inside if it's been compromised: I have an old Healthways tank that still has the lining. I think Charlie says he tumbles his with a whole bunch of screws in it for a good long while...
JB
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jviss
Pro Diver
Posts: 209
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Post by jviss on Sept 10, 2018 4:07:34 GMT -8
Yes, by all means, remove the vinyl from the inside if it's been compromised: I have an old Healthways tank that still has the lining. I think Charlie says he tumbles his with a whole bunch of screws in it for a good long while... JB Thanks for your reply. I was referring to the outside vinyl cover being compromised. USD describes these in their 1967 catalog thusly (page 12): The 53's were only available with the yellow vinyl coating, not galvanized. On mine, the interior coating looks good. The exterior coating is breached in places, with orange rust showing. For context, I bought these in 2007 with a 2006 hydro. I posted here about them, and I have now returned to this site after an eleven year hiatus. Wow, time flies. I think the ideal solution would be if I could strip the vinyl and have the tanks hot-dip galvanized; I don't even know if that's an option, though. There are galvanizing services for things like anchors and chains, I don't know if they would do tanks. Second, I don't know if that's O.K. for a SCUBA tank. One would think it would be fine, as it is commonly done to new steel tanks. Other than that, I bought that can of ZRC Galvanite galzanizing coating. www.zrcworldwide.com/products/zrc-galvilite. (They have several galvanizing coatings, I don't recall why I selected this particular one.) BTW, I received another quote on hydro from a cylinder service company (non-SCUBA specific) of $20 for less than 3000psi and $22 for 3000psi and over. That's better! I think I'll have them hydro'd before I invest the time and materials in refinishing them.
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Deleted
Deleted Member
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Post by Deleted on Sept 10, 2018 6:36:25 GMT -8
Both of my twin 38's are/were vinyl coated on the outside.....one was coated on the inside but the dive shop I obtained them from tumbled them for me and removed the coating.......the first set......a set of Voits I stripped the vinyl off with a sharp knife, then sanded the remaining little pieces the knife wouldn't remove. Then looked at a couple of galvanizing shops, one just a few miles away and they refused as they had no way to immerse the tanks without filling the interior with their solution........these have the 1/2 pipe thread by the way.........then I got the bright idea of having them chromed or nickel plated..........after finding someone who would and was told the cost of chroming...I opted for just nickel plating.......came out pretty good, but the little scratches left by the sandpaper didn't take the plating.......oh, well.....I painted them with refrigerator paint......left them in the hot Texas sun to bake the paint on (it was late August)...had the set hydro'd and VIP'd and still using them 25 years later........the second set I bought in 2005 on ebait, they are USD & still has the vinyl coating on the outside, light rust shows thru on some scratches but no bubbled vinyl, they were hydro'd in 06 and I haven't had them tested since.....I pump my own gas now so the little I dive these last years I don't need no hydro.
Have toyed with the idea of stripping them but probably need to have the 2nd set tested first.
The point is, a little rust isn't going to hurt as long as it isn't deep and heavy and you remove it occasionally and paint or cover it with cold galv.......I have even considered using that stinky stuff they put in the bed of pickup trucks but it is only in black.......tuff stuff however......would make good permanent boots.
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Post by nikeajax on Sept 10, 2018 8:05:30 GMT -8
Yep, I agree with Michael! If it's just surface rust, just spray some clear coat on 'em: we need to preserve their history, like on my HW: It's my opinion that not all gear should look like new, but proudly show a patina JB
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Post by Seahuntjerry on Sept 12, 2018 17:12:25 GMT -8
Your reserve seat in the part with the pin in it.
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Post by Seahuntjerry on Sept 12, 2018 17:15:04 GMT -8
Sorry made a mistake your guys got it figured out!
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Post by duckbill on Sept 12, 2018 19:57:09 GMT -8
Then looked at a couple of galvanizing shops, one just a few miles away and they refused as they had no way to immerse the tanks without filling the interior with their solution. They seem a bit unimaginative. Why couldn't they do it if you filled the cylinder with sand (for mass), and screwed in a bushing and a three foot length of galvanized pipe as a breather to remain above the surface to allow pressure to escape? It just seems to me it could be done. Beware of electroplating. Electroplating causes hydrogen embrittlement in the steel that should be baked out after plating.
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Post by tomcatpc on Sept 1, 2019 15:17:23 GMT -8
I finally got around to diving these today!!! I thought I was going to be overweighted, actually ended up considering adding one pound, maybe? These were a lot more bouyant than I thought they would be. But with 4 lbs on my belt, I was almost perfect at 30-40ish feet. Above that and I felt a bit light, but not too bad. Somewhere over the year and have these sat in my basement the PSI dwindled to 1500 PSI. I'm guessing the manifold is to blame? I've heard these are a pain in the bum to seal? If that is all they leaked in over a year...not going to complain. I think if I start a dive with a full 2250 PSI and 4 lbs, I should be good? I wore a hosercollar BC, but needn't have bothered, did not use it at all. Mark
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Post by crabbyjim on Sept 1, 2019 16:41:24 GMT -8
Put them under water to find the leak. It might be as simple as a loose fitting connection.
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Post by tomcatpc on Sept 1, 2019 17:27:35 GMT -8
Right now they are out of VIZ and almost out of air, so I'm not going to have them in the water anymore this season. I'm going to have them VIZ'd sometime over the Winter then I will see what is going on. I'm hoping you are right. I have heard that US Divers doubles manifolds sometimes can be a pain to get sealed good? Sure had fun diving them. Mark
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