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Re: [PSUBS-MAILIST] Side Thruster Removal on K-250 #118

Brian,

They are rolled (leg out) angle iron, which is what George called for originally. The issue was not the connecting welds, but the degradation on the leg side of the steel itself, which had rusted away substantially. So we build them back up while we were at it. They changed to T section later. If I was doing it again, I'd do Ts, but you almost have to build them in place. Lots of work.

Internal rings are not less critical for welding, but are less demanding, I guess you'd say. The Mermaid subs from Germany had stitch welded rings inside, like long tacks just to hold them in place and help distribute load under pressure. Perry welded them like full penetration welds, whether inside or outside. Now, outside welds DO have to be full penetration welds, as the rings are in tension rather than compression.

You should be okay welding that stuff in there, especially if the hull cylinder is built to close tolerances. That makes life a lot easier.

Vance


-----Original Message-----
From: Brian Cox <ojaivalleybeefarm@dslextreme.com>
To: personal_submersibles@psubs.org
Sent: Tue, 27 Jan 2009 8:35 pm
Subject: RE: [PSUBS-MAILIST] Side Thruster Removal on K-250 #118

Hi Vance,
                On the inside stiffeners,  I assume that they are probably "T" shaped,  since those are basically resisting the outside pressure,  how critical are those welds?  The reason for my question is that I was hoping to do some welding myself.   I can weld farely well but not like a pro.  It seems to me that is an area that is less critical than others.
 
Brian
-----Original Message-----
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org]On Behalf Of vbra676539@aol.com
Sent: Tuesday, January 27, 2009 6:15 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Side Thruster Removal on K-250 #118

Brent,

I sympathize. The same thing happened to my K350 and we burned better than thirty pounds of rod putting in overlays to get the wall thickness on the hull cylinder back to something safe. I had some deep pits (although small in cross section). Two areas were down to about .125". We used acoustic reflective thickness measuring in a 1" grid pattern to map all that out, and ended up throwing our hands in the air and overlaying very nearly all of the bilge from the aft ellipse (which was okay) forward for almost two feet! Plus there were a handful of small spots forward of that. We even had to do some buildup on the ring stiffeners in a few places. Man, you talk about putting some hours in behind a welding hood!!! I'm here to tell you, that was a job.

Now I'm rebuilding the main ballast supports, and I've still got to add a couple of penetrators. All that and be ready for sandblast and paint by the end of February. Nothing to it, right?

Vance


-----Original Message-----
From: Brent Hartwig <brenthartwig@hotmail.com>
To: PSUBSorg <personal_submersibles@psubs.org>
Sent: Tue, 27 Jan 2009 6:54 pm
Subject: RE: [PSUBS-MAILIST] Side Thruster Removal on K-250 #118



Hi  Frank,

The sub has been painted a couple of times, and so I'm not sure what exactly they did.  I think the original paint is still there, since it doesn't look like the sub has ever been sanded or sand blasted.  All the little weld splatter is still there, of which would of been very easy for them to sand off.  From the looks of it, I would guess they only did stick welding on the sub, and did it very quickly.  There is some voids next to some of the weld beads that look like they used to much power for those welds, and then didn't make another bead to clean it up. I plan to TIG those voids up.   I have some pictures in regards to this I'll post in a bit.

I've sanded some test areas, and there is a pretty good gray primer at the base that is still protecting most of the exterior.  I don't see any of that primer on the interior, so I think they skipped that coat in there.  Most the rust on the sub is from it being left outside for the last 10 plus years, and allowing water to get in thru a open hatch and not draining it.  I cleaned up the mud, loose paint, and water about a year before I acquired the sub and drilled a .25" hole at the bottom of each ribbed section, so it would at least drain, and not deteriorate as fast as it was if it stayed there longer. 

The worst rust pitting is were the lead slabs were attached,since they didn't put any spacers between the lead and the painted metal.  That area couldn't breath and dry out easily.  So I might need to replace the main steel vertical panels on both skids, as well as the lower horizontal strip, with SS.


Regards,
Szybowski




From: ShellyDalg@aol.com
Date: Thu, 22 Jan 2009 14:58:27 -0500
Subject: Re: [PSUBS-MAILIST] Side Thruster Removal on K-250 #118
To: personal_submersibles@psubs.org

Hi Brent. Good pics. What type of paint was used on George's subs? I see where the rust has gotten pretty bad in some spots, and I wonder if it's caused by simple lack of maintenance, or not enough protection in the first place. Heavy zinc paint stands up well if maintained properly. Where two components are bolted together, there are several solutions to prevent rust. Delrin disks, bushings inside the bolt holes, judicious painting of all exposed parts, stainless, anodes, and lots of other ideas/methods are easy solutions.
I designed my sub so I can dis-assemble it quickly and easily for maintenance/repair. I should be able to strip it down to the bare hull and re-assemble it in a day, with minimal tools. That way I will be able to get it clean after dives, and touch-up any paint that needs it, without having to sit in the shop for a week. I like the idea of putting plastic/nylon bushings in the bolt holes. Stainless bolts and nylon/stainless washers, so the potential for rust is lessened. There are some places where I'll be using brass bolts with stainless nuts, and some places where I'll use lead bolts with stainless nuts. I have some parts that need to be very strong, and others that are designed to break-away if needed. Brass fasteners are good in some spots because they may need to be drilled out for removal. Here's a quick sketch of one place where it's needed.
Because the fairing covers the mounting tab, I'll be welding a stainless nut onto the bottom of the tab. The brass bolt head can be cut/ground off if need be to remove the fairing. The nylon bushing keeps the different metals from corroding together, and once the brass bolt head is gone, the bushing and fairing can be lifted off. Then some vise grips will pull out the brass bolt, or if needed, drill out the bolt because it's soft. This of course will only be necessary if I don't maintain that particular connection and allow it to get crusty.
http://www.frappr.com/?a=viewphoto&id=1578526&pid=10804946&myphotos=1
Spare bushings, washers, brass bolts, etc are just a few things to carry along in the field for repairs/maintenance. I want to be able to repair this thing with a minimum of tools when I'm out some where remote. Frank D.

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