RE: [PSUBS-MAILIST] Hot-galvanize stainless steel ?

[Alec Smyth <Asmyth@changepoint.com>]

Carsten, maybe I'm misunderstanding it, but as I understand your description
you would have:

- A stainless shaft (or "key")
- A stainless insert for it welded into a dropweight of plain steel

If you galvanize the drop weight (with the insert already welded of course)
then the key and the key-hole would be of different metals so the corrosion
problem would be worse than if they were both just SS. Wouldn't it be enough
to just paint the drop weight like the rest of the sub for corrosion
protection purposes, but leave the key-hole unpainted? If you wanted to get
really fancy, you could sleeve the shaft in plastic like nylon or teflon, to
prevent it from sticking after a year in the water.

rgds,

- Alec

-----Original Message-----
From: MerlinSub@t-online.de [mailto:MerlinSub@t-online.de]
Sent: Thursday, January 24, 2002 11:49 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Hot-galvanize stainless steel ?


"Dan H." schrieb:
> 
> Carsten,
> 
> Why not just weld in a stainless steel plate with your key way already
> in it into a hole cut in your steel weights.  Instead of cutting out the
> key in the actual steel weight, weld in a piece of stainless for the key
> to fit into.  

That it exact was I want to do. Maybe my description was a little short.

> Even if you had the whole thing galvanized and it didn't
> take well to the stainless it wouldn't matter.  Actually, the part of
> the key way in contact with the key will probably wear through the
> galvanize in time anyway just from rocking back and forth in use, won't
> it?

That is exact the question - would the galvanize hold on the stainless
- or not ? I think that if the zinc gives way from the key-hole - we
have a direkt contact from two parts of Stainless steel with a very
little
gap filled with saltwater between them - all the time in seawater -
maybe 
the hole year. That should generate maybe a corrosion problem - and if 
one of the key-hole surface has to much structure on it - the key will
not turn. 

Maybe it would be better to make the key-hole-plate  from normal
carbon steel. I am not affraid that the zinc gives way during 
"Using the key". If I use it - the drop weights gives way and the
sub is not longer able to dive - so the weight will be lost and will not
repaint..  

> 
> Just a question; why didn't you use lead for your drop weight?  There's
> so much more weight for the area it takes up.  A ton of old tire weights
> doesn't make that big of a pile.
> 
Maybe I will do it - a drop weight build from 1/3 inch strong steel
plates  
as a box - and than filled with lead. It will be depents on the final 
weight calclulation - some month before CSSX contact the water in our
river.

Carsten

> Dan H.
> 
> Carsten Standfuß wrote:
> 
> > Hi submadmans and ironheads,
> >
> > One question about metalurgy :
> >
> > Is it possible to Hot-galvanize stainless steel ?
> >
> > I want to build the drop-weights from normal mild
> > and cheap steel and hot-galvanize it.
> > The release-key will be made from stainless steel (SS).
> >
> > For the reason that the welded key-hole inside the
> > dropweight can be made easy from the same plate as
> > the key and with the same waterjet cut - I ask this
> > unuseual question.
> >
> > drawing without scale : (and below 40 KB :-) )
> >
> > I = Stainless steel release key
> > O = Stainless s. hot galv.? key hole
> > = = mild steel hot galv.drop weight
> >
> > _____________________________________
> >
> >                  IIIIIIIturn90°
> >                  I
> >     =========    I    ========
> >    ==========OOO I OOO==========
> >   ===========  IIIII  ===========
> >
> > _________________________CS-1/2002___
> >
> > And please - I know that a full SS drop weight will fit
> > the problem.. .. but I have three weights of 1,3 ts -
> > means it generate another one..
> >
> > regards - Carsten