RE: [PSUBS-MAILIST] o-ring hull penetrations

[Alec Smyth <Asmyth@changepoint.com>]

Dale,

Thanks for the response. Was there any particular grade of SS recommended? I
just spoke to a welder, and he way unsure whether 316 or 316L. Mind if I ask
what steel you used for the hull?

thanks,

-Alec

-----Original Message-----
From: Dale [mailto:heinzind@cadvision.com]
Sent: Monday, December 11, 2000 3:25 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] o-ring hull penetrations



-----Original Message-----
From: Alec Smyth <Asmyth@changepoint.com>
To: PSUBS (E-mail) <personal_submersibles@psubs.org>
Date: Monday, December 11, 2000 8:46 AM
Subject: [PSUBS-MAILIST] o-ring hull penetrations


>I am in the process of machining mechanical hull penetrations for a couple
>of stainless shafts (a weight drop and a hatch dog). But I've run into an
>embarrasingly basic question!
>
>The o-rings have to seat against a hull insert that is made of alloy steel
>so I can weld it to the hull. Alloy steel is obviously going to need
>corrosion protection. So the issue is, do you use some sort of stainless
>sleeve in the hull insert, or is it good enough to paint carefully and let
>the o-rings seat on paint? So far I have machined these surfaces to a
mirror
>polish and intended giving them a very fine layer of powder coat once
>welded, but it bothers me that paint thickness might not be very precise.
>
>Another approach would be a stainless cup-shaped insert with a static
o-ring
>at the bottom (hard to explain without a picture), but maybe I'm
>over-complicating things again.
>
>What's standard on a K boat for example?
>
>
>thanks!
>
>
>- Alec Smyth
>
>

The K-250  uses a stainless insert for the "O" rings welded to the mild
steel hulll.. I just went to my local welding shop, and they gave me the rod
I needed, and it welded very easy.. all the shafts are stainless as well..
the only problem I had, is when I welded the stainless inserts into the
hull, they shrunk, and my shafts would not go through.  I had to ream them
once they were installed, and stainless does not ream very easy..but if you
are careful, they will..
this is very similar in design to a hydraulic cylinder, which will hold
several thousand psi.
dale