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georgeaustin
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Twin 38's Back in Action

Mon Jun 27, 2016 9:25 pm

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Found a rattie set of Twin LP38's rooting around in the boss's gear locker. I'm told they were left outside for a few years which explains the corrosion on the outside. I took the old Sportsways pack, harness and bands off. Interestingly, The Sportsways pack/harness has the same profile as a pretty good shape Kam EZ pack I have laying around without anything to do - so I'm going to drill a hole (which is already marked) in the Kam EZ for my tank band carriage bolt and spacer assembly - that's going to work out pretty well - all I had to do was pull off the single tank cam buckle thingie.

I disassembled the Sportsways manifold and noted bad o rings but the seat looks corrosion free and in really good shape.
1.) Do I need to do anything besides a good ultrasound cleaning and replace the o rings in the manifold?
2.) Tank neck o rings - just clean the threads and get new o rings? The o ring groove in the tank neck looks fine.

I peeked inside the tanks with a light and don't see any corrosion at all besides a tiny orange spot in one about the size of a grain of rice. I see no pitting.

3.) These look to me to be 3/4 straight pipe threads? That would be good news.

My plan is to get this set in the water again so I thought I'd have them tumbled, bead blasted, hydro'd and stickered.
Maybe its the amount of corrosion around the tank shoulders but I don't see any markings besides - : 8 @ 81
4 o 76
4 02 90 ( on both tanks )

What do you guys suggest for coating the outside? I'm thinking in order of cost 1.) Chrome 2.) Flame spray 3.) Hot dip galvanized 4.) Powder coat 5.) Tractor paint.

I'm leaning toward chrome if my guy can make the $$$ somewhat reasonable. Flame Spray looks bad a$$ and tractor paint is just OG cool. Course, a very cool powder coating color works for me too - like Mint Julep or Root Beer maybe -

Thanks

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georgeaustin
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Re: Twin 38's Back in Action

Mon Jun 27, 2016 9:32 pm

o, yeah, new burst discs as well, I imagine - forgot that.

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ScubaLawyer
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Re: Twin 38's Back in Action

Mon Jun 27, 2016 9:54 pm

Looks like a fun project! When it comes to overhauling a valve / manifold be sure and find an exploded diagram for it. Bryan probably has one in the manuals and catalogs section. I say that because in addition to O-rings, there can be one or two gaskets in there as well (and well hidden). Good luck. Keep us posted. Mark
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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8dust
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Re: Twin 38's Back in Action

Mon Jun 27, 2016 11:46 pm

I have a chrome tank and without a doubt, it looks Bad Ass and then some, in my living room... I call it the Cylon Warrior and have one of the Nemrod regs with the really fancy Art Deco can backs mounted on it, absolutly beautiful, but the chrome trapped moisture behind it worse than any coating I've ever seen and it's totally unusable. Can't imagine that USD vinyl causing worse rust. I have to keep it turned just so, or the giant flaking rust blisters show and kinda take away from my display. I'd love to strut around with a chrome tank, especially a set of doubles, but I predict very poor results long term, and eventual total failure. Sounds like the tanks are in nice shape so IMHO, don't screw them up. I'd go galvalite (sp?) or white tractor/propane tank paint .
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georgeaustin
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Re: Twin 38's Back in Action

Tue Jun 28, 2016 12:17 am

Thanks guys -
Mark, I already caught a sneaky little Teflon washer trying to stay hidden in the main valve - it looks fine though.

It only makes sense that even a good chrome job will look great on the surface but probably not perform well diving. Perhaps that is true for powder coating as well. . . . I imagine just based in common sense that flame spraying might be the absolute best for this application -

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ScubaLawyer
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Re: Twin 38's Back in Action

Tue Jun 28, 2016 12:30 am

georgeaustin wrote:Thanks guys -
Mark, I already caught a sneaky little Teflon washer trying to stay hidden in the main valve - it looks fine though. -
Look inside the J-Valve side of the manifold (the end where the outer threads are). If you see a hole that an Allen wrench will fit into - that has to be backed out and the gasket inside usually needs replacement, at least on the USD ones I've worked on. Mark
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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georgeaustin
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Re: Twin 38's Back in Action

Tue Jun 28, 2016 2:50 pm

Correction - My valve manifold is a Sportsways SJ2 (704C) with 3/4 straight pipe threads for 15/16 tank openings.

crimediver
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Re: Twin 38's Back in Action

Tue Jun 28, 2016 10:37 pm

I know powder coating requires baking the item coated by the powder to allow the powder to melt and flow. Temps required can go anywhere from 200 to almost 400 degrees Centigrade. Tanks can be damaged by heat and lose the temper. I would never subject a tank to heat and if a shop suspects a tank has been repainted or powder coated they won't fill it.

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fishnbeer
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Re: Twin 38's Back in Action

Tue Jun 28, 2016 11:54 pm

George congrats on your new 38's. It will be a fun worthwhile project. As far as the exterior finish I would go for ZRC galvanizing paint. It's good paint, roll it on (several coats) and it will give a good protective finish.

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antique diver
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Re: Twin 38's Back in Action

Wed Jun 29, 2016 7:06 am

Those cylinders are already Galvanized which is much much tougher than any coating you could put over it. I would first suggest trying to clean the white oxidation off with CLR, a product available in grocery stores. They may come out looking ok, but if not you can still proceed with some other coating. It will only cost you about $5 to give it a try, and they need cleaning up anyway before you put any coating on.

I have used ZRC Galvilite with pretty good results, but just over bare steel. Seems to me it takes a few weeks to really harden up, and it will never be as scratch resistant as the hot dip zinc that is now on your cylinders. I prefer original galvanizing for its ruggedness even if it doesn't look new and shiny. There is something to be said for original and experienced looking.

Maybe some other forum members have had success cleaning off the zinc oxides, and could make some other suggestions as well...?
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