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[This message is converted from WPS-PLUS to ASCII] ------- Forwarded message Posted: Fri, 01 Dec 95 00:00:01 -0500 Date: Fri, 01 Dec 95 08:09:01 -0500 Author: j. scott landon [This message is converted from WPS-PLUS to ASCII] Doug, <<she's dead.>> my apologies for commenting about your dead mother. <<First I have never bent or broken a valve knob (stem)>> without doing a laser alignment, you can't say for sure that it is bent or not. it may just not be bent enough to make a difference. <<Do I gather from your statement "you have got to be scootering to hit the ceiling that hard" that you don't swim in caves with lots of flow and understand the physics of a mass and stream velocity?>> i swam jackson blue just recently with serious flow after one fo the battery packs in the zepp died at the beginning of the dive. and as a chemical engineer, i'll do all the physics you want to do. should we start with quantum mechanics? we did that in physical chemistry classes. <<Considering your recommendation on stainless for large diameter valve stems: Can you recommend the grade of stainless steel to use to avoid crevice corrosion.>> i would use 316L. i took materials courses with my chem e classes and i now work in a chemical plant where we are constantly working with materials in high corrosion environments. <<Should it be desensitized, passivated, etc. Some of us cave divers also like dive in saltwater (we don't limit our experience).>> if you want to stress relieve the stem after machining, you can. i don't believe you need it for this application. the salt water will not cause chloride cracking at normal temperatures. the 316L will stand up to the pitting and attack far better than 304. <<Do you know anything about some of the problems that were experienced by some manufacturers when they used the wrong materials (including the ScubaPro Mk15 regulator piston)?>> wouldn't own one of those pieces of high priced junk. i stick with poseidon diaphragm first stages. if i really want a piston first stage, i'll buy a sherwood. <<Do you have any projections on the rate of crack propagation or pitting in stainless and the associated failure rates. If you don't have expertise in materials for underwater use then you may wish to refrain from considering yourself an expert. Some of us do.>> do you refrain or are you an expert? your 316L should work just fine. if you really want to worry, use hastelloy C276. how's that cowboy. bring a big checkbook for the hastelloy. maybe you'd prefer inconel. i'll give you a list of materials until you accept that i know one or two things about materials. <<You are a list vulture; you sit around and make these posts and then respond "i'm not on techdiver, so don't respond to me on the list." What sort of nonsense is that? If you have something to say to me, then grow some balls and say it to me.>> if i could get on techdiver, i would. i have tried repeatedly, but the system cannot deal with my mailing address. it bounces my attempts. i have asked jr oldroyd to manually add my name, but he says he cannot. no nonsense. i can only read messages through the web. if you posted your answer solely to the list, i may have never seen it. i wanted to make sure i got your response. where do i send the check for the brass knobs <G>? scott ------- End of Forwarded message
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