Re: [PSUBS-MAILIST] Stainless Welding Question

["James Frankland" <james@guernseysubmarine.com>]

Hi Scott\Frank\Alec,

Thanks for the replies.  309L it is.

Ive actually done a couple and i did them using 309L stick electrodes.  I did a suitable bevel as frank says preheated and welded the root with 2.5mm electrode, then went up to 3.2 for the outer run.

Just took a while thats all.  I would point you to my website but its broken.  Might work for you, depends on your browser.  Another job ive got to do.

Also, i think im going to make a "port" as Frank suggests because i want to get one of those standard penetrators on that are now available through the club.

Thanks again for the advice.

James

----- Original Message -----
From: ShellyDalg@aol.com [mailto:ShellyDalg@aol.com]
To: personal_submersibles@psubs.org
Sent: Wed, 24 Feb 2010 11:52:06 EST
Subject: Re: [PSUBS-MAILIST] Stainless Welding Question

Hi James. I would go and talk to the guys at your local welding store. If
you are welding stainless parts onto/into carbon steel parts, stainless
filler  is always used. Maybe your ship building friend was talking about
putting steel  fittings into the steel hulls.
Joint design is also a critical factor. Thru-hulls are subject to some
unusual stresses.
The area of the hole should be reinforced either by adding weld beads
around the hole to increase thickness or in the case of multiple penetrations a
thicker "disk" should be welded in. ( not ON )
For a single penetration, the hole in the hull should be beveled on the
exterior, and stainless filler rod built up in the bevel, making a conical
shaped "plug" of stainless. Typical bevel is 22-1/2 degrees. If the hull is
1/4"  to 3/8" it should be doubled in thickness at the hole.
As for corrosion, you could use steel through hulls like schedule 80
couplings or nipples but they won't be painted on the inside and will rust out
more quickly than 316L-SS fittings.
Pre-heating the hull and fittings is important too, with a slow cooling (
torch work ) after welding.
Re-polish the inside of the fitting after completion to keep it's
anti-corrosion properties at maximum.
I'm using mostly 1" schedule 80 seamless nipples from McMaster-Carr at $30
each.
The really sweet way for multiple penetrations guys use now is to machine a
 "port" with "O" rings like a small window and install a thick stainless
disk  with threaded holes for penetrations. This way you can easily replace
the disk  with more or less holes like if you wanted to add a manipulator arm
or  lights/cameras at a later date. There are some photos of these available
on  various member projects on the psubs site.
Frank D.