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Hello Frank,
That sounds like a good alternative to having to have some
machined. It's a little like the machined ones Dan H. did on
Persistence. You might consider using 316 SS sch, 40 or 80 couplings
instead of nipples welded into the hull. That way if some thing shears off you
won't likely need to weld in a new one. The threads on the nipples are the weak
point. My relative built both his hyperbaric chambers with SS couplings
for the thru hull. If you put steel plugs in both ends of the coupling before
welding, you'll have a better chance of limiting the distortion and keep the
threads clean. Here are some pictures of said couplings.
I have a source for 316 SS couplings that I plan to use in my plate
thru hulls. If you use larger couplings then you need, and install a
reducer for your current needs, you will have more options for changes in
the future. I liked your core idea so much, I worked up a CAD assembly of what I
was thinking would work well.
I don't plan to have any threads or O-ring glands in my main
pressure hull. They are all on removable parts. I even figured out a
design to hold on my side conical conning tower windows with out using screws to
hold the retaining ring on, using a SS V clamping style arrangement. No
more rust streaks for me, thank you very much.
Cheers'
Szybowski
From: ShellyDalg@aol.com
Sent: Thursday, August 06, 2009 10:45 PM
Subject: Re: [PSUBS-MAILIST] Electrical thru-hulls Work on my sub has been going steady lately, and I was getting ready to
start wacking holes in the hull for the wires.
Well, I was re-thinking my simplified thru-hull design and decided it was a
maintenance nightmare.
My latest solution is this........
Still use the simple stainless nipple welded into the hull, with a ball
valve threaded onto the inside.
( You know me.....EVERY hole gets a ball valve.)
Here's the new part.....instead of welding shoulder stops into the inside
of the nipple, and potting the conductor rods in epoxy in the welded nipple, put
the rods and epoxy in a bell reducer, and screw it onto the outside of the
nipple. This makes the epoxy plug a wedge shape so it can't be forced into the
smaller diameter nipple, and it makes the task of potting with the rods in place
much simpler as it can be done on the bench, rather than trying to glue the rods
into the nipple that's already welded into the hull.
The biggest advantage here is that if there's a problem with the
assembly, it can be unscrewed and replaced with just a pipe wrench, rather than
having to drill out and re-pot the welded nipple.
Maintenance and repair are a couple of the biggest factors when I'm
pondering how to accomplish something. I don't want to be far afield on a dive
trip and have a simple part break and take days to fix.
This thru-hull design makes it simpler to do the first time, and
replacement MUCH faster and easier. This way I can carry spare potted reducers
and affect a repair in minutes rather than taking all day to drill, re-pot with
epoxy, and wait for it all to cure before going back out.
Anybody got any thoughts on this newest design? I welcome criticism. Frank
D.
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