Surplus Twin 50s (I think)

Talk about vintage tanks and valves. Hydro and VIP testing, cleaning, painting, coating, Valve parts and repair.

Moderators: Herman, captain

User avatar
SurfLung
Master Diver
 
Posts: 1028
Joined: Sat Jan 01, 2011 2:03 pm
Location: Alexandria, MN

Surplus Twin 50s (I think)

Mon Dec 19, 2016 3:55 pm

My Twin 50s Project...

- My son brought me this set of Twin Tanks a couple of years ago. They had been sitting outside of a friend's shed in Colorado. The friend said they were there when he bought the place and he'd be glad to have someone haul them away. So, my son grabbed them and brought them home to me here in Minnesota. As you can see, they were rusty and dirty. I cleaned them up with car wash soap.
Image
Image
- They are a home made set of twin tanks made from military surplus tanks. As you can see they had a USD "dog bone" back pack. Two different tanks bands were used with what looks like a home made J-Rod. The manifold is a very odd looking Voit model with tapered thread 1/2 inch connections in reducer bushings. The stamped working pressure on these is 1800 psi. That and their shape are the same as my "Twin 38s" except these tanks are a little longer. I think these are approximately 50 cf tanks.
- They looked like heck on the outside but when I took the valves off and looked inside they are totally clean and look brand new on the inside. So, the next thing was to get them inspected and hydrotested... I really expected the outside rust would disqualify them. But it turned out to just be surface oxidation and not pitting. The tanks passed inspection and hydro with flying colors.
Image
- Here are the tanks before and after rust removal via bead blasting. It's surprising how tough the old paint can be after curing for a few decades. I decided to only blast off the rust and leave any paint that was tough enough to withstand the blasting.
Image
- This is a photo of the second coat of Galvalite 96% Zinc paint... Note the paint is still wet. Just like zinc plating, galvalite protects steel by galvanic reaction... The zinc oxidizes instead of the steel oxidizing. So, these tanks are WELL PROTECTED.
- I plan to replace the oddball manifold with the original USD styled Voit manifold... I got a like-new one from the Scuba Museum. My buddy Rich is polishing some original chrome tank bands which I'll mate with an Allan Klauda military style harness. Should be pretty neat. :)
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

SeaHuntJerry
Master Diver
 
Posts: 303
Joined: Sat Jul 02, 2005 12:45 am
Location: Minneapolis

Re: Surplus Twin 50s (I think)

Mon Dec 19, 2016 6:17 pm

nice :evil: :twisted: :D :lol:

User avatar
Bryan
Plank Owner
 
Posts: 4958
Joined: Fri Jun 24, 2005 11:40 am
Location: Wesley Chapel Florida

Re: Surplus Twin 50s (I think)

Mon Dec 19, 2016 7:36 pm

Finish looks great!
Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB

swimjim
Master Diver
 
Posts: 1341
Joined: Thu Mar 23, 2006 12:28 am
Location: Belgium WI

Re: Surplus Twin 50s (I think)

Tue Dec 20, 2016 9:40 am

Nice score Eben! The tanks look great already. Can't wait to see them up at the pond!

User avatar
SurfLung
Master Diver
 
Posts: 1028
Joined: Sat Jan 01, 2011 2:03 pm
Location: Alexandria, MN

Re: Surplus Twin 50s (I think)

Tue Dec 20, 2016 10:17 am

Image
- Galvalite is dry. I'm going to let it "cure" for a couple of weeks over the heat register. Rich says the bands are polished shinier than a "diamond" in a dark part of a monkey's anatomy... Haven't seen such a thing (or thought of it) but it sounds pretty shiney.
Image
- This is the like-new Voit manifold I got from Rob at the Scuba Museum.
- Thanks for the kind remarks :)
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

User avatar
SurfLung
Master Diver
 
Posts: 1028
Joined: Sat Jan 01, 2011 2:03 pm
Location: Alexandria, MN

Re: Surplus Twin 50s (I think)

Mon Jan 09, 2017 1:03 pm

Some Assembly Required...
Image
- I'm going with brand new stainless bands and the Sea Hunt harness from Allan Klauda.
- Bushings and Valves. I bought a huge 1-3/8" box wrench for the bushings... The 1-7/16" wrench I had from some other bushings was too large. Anyway, Menards had a cheapy Chinese version of this box wrench for only $15. Over a foot long for good leverage.
- Using the homemade tank vise I have pictured in other posts, I secured the first tank and test screwed the bushing as tight as it would go to see how high I should wrap the Teflon tape. Then, I wrapped 6 wraps and screwed in the bushing as far as it would go with the box wrench.
- Screwing in the twin tank manifold valve is something that always risks damage from the wrench... Since there really is no wrench that fits it adequately. Well, this time I used an older, beat-up manifold as a wrench. I screwed it onto the valve I was installing and it gave me plenty of wrenching leverage without marring the new manifold valve. Again, test fit to find the depth and then installed it as far as it would go with 6 wraps of Teflon tape. Repeated everything for the other tank.
- The center on/off valve section can be challenging to get a good seal. I think making sure the contact surfaces are clean and smooth is the first step. Did that with OOOO fine steel wool and wiped dust off afterward with a paper towel moistened with food grade silicone spray.
- Assembly went well... I took my time and made sure everything was lined up, etc. I only had enough air in my other tanks to pressurize these half way (800 psi). They have been holding the same pressure for 24 hours so I don't think I have any leaks... We'll check better at higher pressure. :)
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

Return to Tanks and Valves

Who is online

Users browsing this forum: No registered users and 3 guests