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Greetings James, Your right, I am on another planet. We finally got two way internet installed over here on the ice world of Hoth. Your hatch and conning tower look to be to heavy and shiny to be of any use to you. So you should just crate them up and send them on over to me. I have a good use for them over here. Just don't forward the machining bill. ;)' As for the gland, the K-250 plans show a 15 degree angle, which looked to me like it was a little more over kill then needed. So it makes sense to me that George lightened that up a bit to 10 degrees for the K-350's. I've seen a couple of other gland drawings that show the sharp outside corners of the gland being rounded over just a touch to about a .005" radius. Seems to me that if that was done, it would help prevent some damage to the O-ring in some situations, as well as help keep paint from chipping if it is needed on that flanges surfaces. James are your hatch and conning tower flanges SS or cladded with SS? I can see were if a person wanted to clad the flange that has the gland in it, and you wanted the gland to also be cladded, that you could first machine in a over sized gland. Then fill it with SS and then machine it again to your finished specs. But it might very well be cheaper to get the same strength of the steel flange with a little larger SS one. Cheers, Brent "Never try to teach a pig to sing; it frustrates you and annoys the pig." ~ Mark Twain " Lettin' the cat outta the bag is a whole lot easier than puttin' it back in." ~Unknown "If you get to thinkin' you're a person of some influence, try orderin' somebody else's dog around." ~Unknown > To: personal_submersibles@psubs.org > From: james@guernseysubmarine.com > Subject: RE: [PSUBS-MAILIST] Coved O-ring Groove > Date: Fri, 22 Feb 2008 08:53:51 +0000 > > Hi Brent. > > I like the snow cave! Looks like that bit in "Alien" when they go troopsing off to find the space ship. I'm sure your on another planet! > > Anyway, about the hatch groove. > > > Not to long ago Frank D. asked about whether he should cut a coved or square O-ring groove in his hatch, and I don't remember if any one answered > him? > > I just had mine machined at a professional shop 2 days ago. The Kittredge plans show a square groove with a 10 degree angle on the inside diameter. I assume this angle is to allow somewhere for the o ring to compress into. Anyway, thats how i've done it, right or wrong. You can see it here. > > http://www.guernseysubmarine.com/index_files/Page9271.htm > > James > > > > ----- Original Message ----- > From: Brian Cox [mailto:ojaivalleybeefarm@dslextreme.com] > To: personal_submersibles@psubs.org > Sent: Thu, 21 Feb 2008 23:38:45 -0800 > Subject: RE: [PSUBS-MAILIST] Coved O-ring Groove > > Wouldn't the hatch be metal to metal and the pressure coming in at the > hatch/seat division make the o ring try to extruded into the sub. The > pressure that the o ring would extrude would be very high, higher than the > collapse pressure of the sub I would think. > > Brian > -----Original Message----- > From: owner-personal_submersibles@psubs.org > [mailto:owner-personal_submersibles@psubs.org]On Behalf Of Brent Hartwig > Sent: Thursday, February 21, 2008 9:37 PM > To: personal_submersibles@psubs.org > Subject: RE: [PSUBS-MAILIST] Coved O-ring Groove > > > I worked up three more drawings to show what I was thinking a O-ring in a > coved gland or square gland with silicone or urethane filling the square > corners of the gland, would look like being under great pressure. Since I > think there would be far more pressure coming down on the O-ring from the > hydrostatic pressure on the hatch's outer surface then would be coming in > from the space between the hatch flange and seat. Also I would expect that > the more exterior hydrostatic pressure is applied to the hatch that it would > further help seal the O-ring against the seating surface, keeping it from > extruding to the low pressure side of the seal. Any thoughts? > > > http://www.frappr.com/?a=viewphoto&id=4001713&pid=9275457 > > > > Regards, > Brent Hartwig > > > > > > ---------------------------------------------------------------------------- > From: brenthartwig@hotmail.com > To: personal_submersibles@psubs.org > Subject: [PSUBS-MAILIST] Bottomed Out Hatch Flange O-ring Failure > Date: Sat, 2 Feb 2008 15:37:06 -0800 > > I've been thinking about this for some time now, and thought it was time > to talk about it. There has been a fair bit of discussion on O-ring failure > in a hatch, by means of extrusion. I don't think this would be the mode of > failure for a hatch O-ring, and here is why. When the hatch is shut and > under water, the exposed surface area on the O-ring between the two metal > mating surfaces is vastly smaller then the surface area on the top of the > whole hatch pushing down on it. This means that if the pressure is to great > for the O-ring, the hatch mating surfaces will bottom out and then the water > will just start to flow past the O-ring without extruding it. Also if the > hatch bottoms out there will be no place for the O-ring to extrude into. At > this point I think the O-ring would just rather let the water pass between > it and the flat flange mating surface, rather then extrude. Any thoughts? > > I made up a model to better show what I'm thinking the O-ring would look > like when fully compressed into it's gland by a bottomed out hatch flange. > > http://www.frappr.com/?a=viewphoto&id=4001713&pid=9115314 > > > Here is a really great link I found today showing a lot more modes of > O-ring failure then I'd seen any place else. > > http://www.allorings.com/failure.htm > > Not to long ago Frank D. asked about whether he should cut a coved or > square O-ring groove in his hatch, and I don't remember if any one answered > him? I would think the cove would make for less room for a O-ring to deform > into to help keep the metal hatch surfaces from bottoming out. While > watching the Nova show on the Alicia sub called "Underwater Dream Machine", > I noticed that they put a lot of silicone type sealant in the O-ring groove > that is in the large unboltable flange, that keeps the two large steel > pressure hull sections together. I'm guessing they did this to fill the > extra space of a square type O-ring groove, that the O-ring doesn't fill > when in a non compressed state. So there will be more space between the > flanges at depth, to keep them from bottoming out. Any thoughts, or should I > add more O2 to my snow cave? > > Here are two pictures showing snow through the windows of my house. One > shows snow up against a window in the the spa room, and the other shows that > the snow outside my shop window is completely blocking the view out the > window. So when I say snow cave, I mean it. This is not normal for around > here. > > http://www.frappr.com/?a=viewphoto&id=4001713&pid=9115443 > > Regards, > > Brent Hartwig > |