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

["Marsee Skidmore" <heyred@email.msn.com>]

The L indicates low carbon. Welded 316 tends to lose it's corrosion
resistance in the heat affected zone. This has something to do with carbon
precipitating out of solid solution (I think), so lowering the carbon
content fixes it. If the o-ring surfaces are within the heat affected zone,
you'd probably want 316L. It couldn't hurt. - Joe

----- Original Message -----
From: Alec Smyth <Asmyth@changepoint.com>
To: <personal_submersibles@psubs.org>
Sent: Monday, December 11, 2000 12:42 PM
Subject: RE: [PSUBS-MAILIST] o-ring hull penetrations


> 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
>
>