Hello Frank,
Did you say enthusiasm? Be careful what you wish for. ; )'
I've never seen a sub that didn't have continuous welds on the parts of the stiffeners that contact the outer skin. Do you know of any I can look at. Not to say that your method isn't good, I just hadn't heard of it before. I would think it would be a rust nightmare if done on a steel hull. Unless you back ground the part of the ring that was going up against the outer skin like you normally would to weld it, and then after stitch welding it, sand blasted it, epoxy primer it, paint and then fill the groove with a product like Sika Flex 292 and then Rhino coated the whole inside of the pressure hull. I hate having to grind and/or sandblast paint over and over and over and over. There has to be a better way.
That's not to say that all areas of a sub shouldn't be designed, so you can get to them for inspection and maintenance later, as you said. That is one on my biggest things I spend time working up designs for. I've seen so many museum and PSUBs that were not designed this way, and it made working on them very hard if not impossible, without doing some very serious cutting.
The RV Needlefish, for all it's great innovations that I learn much from, had allot of areas you couldn't get to with out destroying the bow, stern, and saddle tanks, to do so. I'm under the impression that trying to bond fiberglass composite, over and onto a steel pressure hull wouldn't be a good bond. This being mostly because they expand and contract at different rates. I would like to hear from others with more actual experience with composites on this. I'll need to ask Karl Stanley about this as well, since Idabel has built with composites attached directly to the paint of the steel hull.
Will the steel hull of the R300 try to expand and contract, at a different rate then the syntactic foam around it, and in doing so, try to break it. Or will the syntactic foam so insulate and absorb heat and cold changes, that they work together?
I'm thinking about casting syntatic foam between the internal ribbing of this K-250 I'm working on, by way of infusion molding it. I will do this after I've installed T stock steel inbetween the support ribs horizontally, and after I've applied a Rhino type coating to deal with the expantion and contraction of the steel. The T stock will do basicly two things, give strength to the hull and keep the syntactic foam from falling out, since on the K boats the support rings only have under cut areas on one side, because they are made of rolled angle iron as most of you guys well know.
I think I would like to heat treat the whole completed pressure hull of my sub if I could, like Karl Stanley did on Idabel. I'm not sure how much it cost him, but I can find out.
http://stansub.fotki.com/the_submarine-1/the_submarine_under/heat_treatment.html
Regards,
Brent Harwig
From: ShellyDalg@aol.com
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] MIG Welding a Sub
Date: Thu, 26 Jul 2007 19:20:29 EDT
Well OK, here's my two cents. I've been welding for 40 plus years, and am still learning but for my sub, tig roots and stick cover passes.This gives X-ray quality welds, minimum porosity, and takes a hell of a lot longer to do.Shielding gas on BOTH sides for the root.For compressive welds like internal stiffeners, a stitch method works best. You don't need continuous welds (and a continuous heat stress zone) around the circumference of the hull when a simple ring is being welded inside. As the pressure increases, the hull will shrink around the ring and a little "give" here is a good thing.Ideally, putting the completed hull in an oven would be good, but expensive.Minimize welds to the pressure hull by welding on tabs, then bolting whatever in place rather than welding some big "thing" on there. This also makes it easier to change or up-grade when you get new ideas or need something extra for a specific task.Don't build anything you can't get to later. Gotta be able to grind and paint on a regular basis.OK......that was more like 5 cents. Keep up the enthusiasm, and remember, this is supposed to be FUN!!!Frank D.
Get a sneak peek of the all-new AOL.com.