Sealing tubes

[defofthecrown]

I've been trying to seal a speargun tube and haven't been succesful. I've tried cork/high density foam sealed w/ silcon, polysulfide, and epoxy.

None of these combinations can keep water from leaking in.

Has anyone been succesful sealing them?

Or is it a waste of time to make it water tight? Just let the water go in and out. I'm using a floatline so I'm not sure how the gun being positively bouyant would be advantages.

I'm thinking solid rubber bung or wood plud w/ o-ring, but I don't want to waste any more time doing things that don't work.

Thanks

 

[Bill]

I solved this one a long time ago.
First find a tube about 2 inches long (5 cm) that will telescope into the one you want to seal. If you can't find one that fits close, use a piece of the same size tubing and slit it lengthwise with a coarse saw blade. You may need to use a file too. After the 2" part slides in and out, I drilled a dozen 3 mm (1/8") holes in it. Give the inside of the tube and the part a vinegar bath, rinse and a good work over with medium sandpaper just before glueing and keep your oily fingers off the surfaces.
Now you need to make or buy a plug that will slip inside the tube but be stopped by the custom part. If the auto supply doesn't have a frost plug that works, you will have to file down a bigger one, have some one punch one out of 3 mm aluminum or do some more file work.
Lightly coat the inside of the tube and the outside of the drilled piece with epoxy and position it. Clean the edge of the plug, thicken the epoxy and glue it in before the first glue joint 'goes off'. After it's dry, I usually run a bead of silicone around the edge of the plug, just in case.
It sounds like a lot of work but I had one gun go twenty years, over a hundred days of use to depths of 25 meters and stay dry as a bone inside, with minimum care.
Bill

 

[icarus pacific]

...and Bill knows about the dry bone!

Here's another quick fix if you can't find a competent welder with a TIG setup that will go below 50 amps. Head over to the plumbing suppy house and get an expansion plug. It'll look like a couple of large flat washers with a compressible rubber doughnut in between. A bolt goes throuh the whole sandwich and gets tightened with a wingnut. Done deal.