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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Calling all you chemists...
Will urine ie human waste corrode 316L valves and pipe? The question is
asked because waste tanks are typically plastic, but Lloyds A1 certification requires all through hull valves to be fire proof. Fireproof valves are typically 316L. I have purchased all my valves from the chemical industry. I have been told that urine will corrode 316 over time. I don't believe it. If 316 is good enough for corrosives in industry, why would it not stand up to human waste? If anybody knows for sure, please let me know. Steve |
#2
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Calling all you chemists...
On Wed, 14 May 2008 17:47:45 +0200, "Steve Lusardi"
wrote: Will urine ie human waste corrode 316L valves and pipe? The question is asked because waste tanks are typically plastic, but Lloyds A1 certification requires all through hull valves to be fire proof. Fireproof valves are typically 316L. I have purchased all my valves from the chemical industry. I have been told that urine will corrode 316 over time. I don't believe it. If 316 is good enough for corrosives in industry, why would it not stand up to human waste? If anybody knows for sure, please let me know. Steve Here's a chemical compatibility chart, which shows 316's performance as "Excellent" in this application: http://www.sscableties.com/chem_pz.htm 316L (low carbon) should have very similar chemical resistance properties at reasonable temperatures. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |
#3
Posted to rec.crafts.metalworking
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Calling all you chemists...
Will urine ie human waste corrode 316L valves and pipe? The question is asked because waste tanks are typically plastic, but Lloyds A1 certification requires all through hull valves to be fire proof. Fireproof valves are typically 316L. I have purchased all my valves from the chemical industry. I FWIW, there have generally been bronze valves in the head on most Ocean charter fishing boats. Karl |
#4
Posted to rec.crafts.metalworking
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Calling all you chemists...
On Wed, 14 May 2008 17:47:45 +0200, "Steve Lusardi"
wrote: Will urine ie human waste corrode 316L valves and pipe? The question is asked because waste tanks are typically plastic, but Lloyds A1 certification requires all through hull valves to be fire proof. Fireproof valves are typically 316L. I have purchased all my valves from the chemical industry. I have been told that urine will corrode 316 over time. I don't believe it. If 316 is good enough for corrosives in industry, why would it not stand up to human waste? If anybody knows for sure, please let me know. Steve Greetings Steve, Stainless steels will corrode faster if not exposed to free oxygen. Stainless that is constantly submerged in salt water will corrode when the same piece above water will not. This corrosion can also be from biological processes. Science News had an article several years ago about stainless piping that had to be replaced in some nuclear power plants because of corrosion induced largely by bacteria. I have machined many stainless prop shafts that were replacements for shafts that had what appeared to be worm holes in them that ran roughly parallel with the shaft axis and were anywhere from 3 to 18 inches deep. Washington State had to have a bunch of stainless pipe replaced on some ferries because the boat builder used it in a salt water system where the inside of the pipes were always flooded. ERS |
#5
Posted to rec.crafts.metalworking
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Calling all you chemists...
On Wed, 14 May 2008 17:47:45 +0200, "Steve Lusardi"
wrote: Will urine ie human waste corrode 316L valves and pipe? The question is asked because waste tanks are typically plastic, but Lloyds A1 certification requires all through hull valves to be fire proof. Fireproof valves are typically 316L. I have purchased all my valves from the chemical industry. I have been told that urine will corrode 316 over time. I don't believe it. If 316 is good enough for corrosives in industry, why would it not stand up to human waste? If anybody knows for sure, please let me know. Steve There was a thread on rec.boats.cruising today in which a lady named Peggie Hall states: ---------------------------------------------------------------------------------------------------------- SS fittings in the sanitation system plumbing??? Not a good choice, 'cuz urine will corrode 'em. At least one trawler mfr who puts all fittings on the top of the tank, with a pickup tube inside the tank on the discharge (a great idea) used stainless fittings and pickup tubes--a VERY bad idea, 'cuz the tubes are corroding, even falling off in pieces inside the tank, in just a few years. -- Peggie ---------- Peggie Hall Specializing in marine sanitation since 1987 Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and Other Sources of Aggravation and Odor" http://shop.sailboatowners.com/boat_odors/ --------------------------------------------------------------------------------------------------------- Peggie has been posting on rbc for some years now and her posts have always been logical and informative. You might try contacting her for additional information. Bruce-in-Bangkok (correct Address is bpaige125atgmaildotcom) |
#6
Posted to rec.crafts.metalworking
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Calling all you chemists...
"Steve Lusardi" wrote in message ... Will urine ie human waste corrode 316L valves and pipe? The question is asked because waste tanks are typically plastic, but Lloyds A1 certification requires all through hull valves to be fire proof. Fireproof valves are typically 316L. I have purchased all my valves from the chemical industry. I have been told that urine will corrode 316 over time. I don't believe it. If 316 is good enough for corrosives in industry, why would it not stand up to human waste? If anybody knows for sure, please let me know. Steve I think it depends on who's urine. Years ago, after a night of merriment, my urine would eat holes in porcelain. |
#7
Posted to rec.crafts.metalworking
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Calling all you chemists...
ERS,
You are correct. I am aware of the rules of use of 316 and that the corrosion protection is the oxygen layer on its surface. The corrosion you described is called crevice corrosion and can occur even in fresh water, not just salt water, but it is caused by oxygen deprivation where all the free oxygen has been consumed in the water. Crevice corrosion will not occur if the corrosive medium is continually flushed with new fluid. It is when the corrosive medium becomes stagnant and its oxygen content is not refreshed is when crevice corrosion occurs. It is the other aspect you mentioned that concerns me, the bacteria thing, that I do not understand. Through proper use and period flushing, I should be able to reduce the risk of crevice corrosion. Steve wrote in message ... On Wed, 14 May 2008 17:47:45 +0200, "Steve Lusardi" wrote: Will urine ie human waste corrode 316L valves and pipe? The question is asked because waste tanks are typically plastic, but Lloyds A1 certification requires all through hull valves to be fire proof. Fireproof valves are typically 316L. I have purchased all my valves from the chemical industry. I have been told that urine will corrode 316 over time. I don't believe it. If 316 is good enough for corrosives in industry, why would it not stand up to human waste? If anybody knows for sure, please let me know. Steve Greetings Steve, Stainless steels will corrode faster if not exposed to free oxygen. Stainless that is constantly submerged in salt water will corrode when the same piece above water will not. This corrosion can also be from biological processes. Science News had an article several years ago about stainless piping that had to be replaced in some nuclear power plants because of corrosion induced largely by bacteria. I have machined many stainless prop shafts that were replacements for shafts that had what appeared to be worm holes in them that ran roughly parallel with the shaft axis and were anywhere from 3 to 18 inches deep. Washington State had to have a bunch of stainless pipe replaced on some ferries because the boat builder used it in a salt water system where the inside of the pipes were always flooded. ERS |
#8
Posted to rec.crafts.metalworking
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Calling all you chemists...
Karl,
Thank you for your response. I do know that bronze has been used for through hulls in the past, but rarely now in steel hulls because of electrolosis issues. Although bronze satisfies the Lloyds issue, its use brings to bear a whole new set of corrosion issues. Steve "Karl Townsend" wrote in message anews.com... Will urine ie human waste corrode 316L valves and pipe? The question is asked because waste tanks are typically plastic, but Lloyds A1 certification requires all through hull valves to be fire proof. Fireproof valves are typically 316L. I have purchased all my valves from the chemical industry. I FWIW, there have generally been bronze valves in the head on most Ocean charter fishing boats. Karl |
#9
Posted to rec.crafts.metalworking
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Calling all you chemists...
Spehro,
Thanks for your response. It gives me some peace of mind. Steve "Spehro Pefhany" wrote in message ... On Wed, 14 May 2008 17:47:45 +0200, "Steve Lusardi" wrote: Will urine ie human waste corrode 316L valves and pipe? The question is asked because waste tanks are typically plastic, but Lloyds A1 certification requires all through hull valves to be fire proof. Fireproof valves are typically 316L. I have purchased all my valves from the chemical industry. I have been told that urine will corrode 316 over time. I don't believe it. If 316 is good enough for corrosives in industry, why would it not stand up to human waste? If anybody knows for sure, please let me know. Steve Here's a chemical compatibility chart, which shows 316's performance as "Excellent" in this application: http://www.sscableties.com/chem_pz.htm 316L (low carbon) should have very similar chemical resistance properties at reasonable temperatures. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |
#10
Posted to rec.crafts.metalworking
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Calling all you chemists...
Bruce,
It is precisely Peggie's response that generated this query. I have spoken to her on the phone about this issue in February. Peggie does not know one stainless alloy from another and could not give me the precise circumstances that created this condition, nor could she identify the alloy used. I respect her knowledge immensely and do not doubt for a second that this occurred and is true, but I am faced with a dilemma and need to understand the corrosion risks better in order to mitigate those as well as possible, hence this query. Please note Spehro's response above. It verifies my initial response to Peggie's statement. There was something else going on. It could be this bacteria thing, but my best guess at the moment is stagnation, free oxygen deprivation and the resultant crevice corrosion was the culprit. In addition to this query, I sent a similar one to the valve manufacturer, but I have not yet received the response. Right now it looks like my solution to the dilemma is to double valve the holding tank exit line, first with plastic and secondly with 316L at the hull. Steve "Bruce in Bangkok" wrote in message ... On Wed, 14 May 2008 17:47:45 +0200, "Steve Lusardi" wrote: Will urine ie human waste corrode 316L valves and pipe? The question is asked because waste tanks are typically plastic, but Lloyds A1 certification requires all through hull valves to be fire proof. Fireproof valves are typically 316L. I have purchased all my valves from the chemical industry. I have been told that urine will corrode 316 over time. I don't believe it. If 316 is good enough for corrosives in industry, why would it not stand up to human waste? If anybody knows for sure, please let me know. Steve There was a thread on rec.boats.cruising today in which a lady named Peggie Hall states: ---------------------------------------------------------------------------------------------------------- SS fittings in the sanitation system plumbing??? Not a good choice, 'cuz urine will corrode 'em. At least one trawler mfr who puts all fittings on the top of the tank, with a pickup tube inside the tank on the discharge (a great idea) used stainless fittings and pickup tubes--a VERY bad idea, 'cuz the tubes are corroding, even falling off in pieces inside the tank, in just a few years. -- Peggie ---------- Peggie Hall Specializing in marine sanitation since 1987 Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and Other Sources of Aggravation and Odor" http://shop.sailboatowners.com/boat_odors/ --------------------------------------------------------------------------------------------------------- Peggie has been posting on rbc for some years now and her posts have always been logical and informative. You might try contacting her for additional information. Bruce-in-Bangkok (correct Address is bpaige125atgmaildotcom) |
#11
Posted to rec.crafts.metalworking
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Calling all you chemists...
On Thu, 15 May 2008 10:40:21 +0200, "Steve Lusardi"
wrote: Bruce, It is precisely Peggie's response that generated this query. I have spoken to her on the phone about this issue in February. Peggie does not know one stainless alloy from another and could not give me the precise circumstances that created this condition, nor could she identify the alloy used. I respect her knowledge immensely and do not doubt for a second that this occurred and is true, but I am faced with a dilemma and need to understand the corrosion risks better in order to mitigate those as well as possible, hence this query. Please note Spehro's response above. It verifies my initial response to Peggie's statement. There was something else going on. It could be this bacteria thing, but my best guess at the moment is stagnation, free oxygen deprivation and the resultant crevice corrosion was the culprit. In addition to this query, I sent a similar one to the valve manufacturer, but I have not yet received the response. Right now it looks like my solution to the dilemma is to double valve the holding tank exit line, first with plastic and secondly with 316L at the hull. Steve It sounds to me as though you have an installation with a holding tank and a thruhull pump out in a steel boat. If that is the situation I'd plumb the thruhull with the hull/seawater in mind as the fittings will have limited contact with sewage... assuming that you flush the lines after pump out, and use plastic for the tank plumbing. Even if you have a bowl to thruhull system, without a holding tank, there is still limited contact of concentrated sewage with the thruhull as you initially pump water and then when it is flushed clean you usually flip the lever and pump until you have blown the lines clear of liquid. Of course, there is some leakage back through the joker valve so sea water seeps back but I'd guess that the majority of the liquid in contact with the thruhull is going to be sea water. I'd guess that the other fellow's recommendation of 316L is probably your best choice. "Bruce in Bangkok" wrote in message .. . On Wed, 14 May 2008 17:47:45 +0200, "Steve Lusardi" wrote: Will urine ie human waste corrode 316L valves and pipe? The question is asked because waste tanks are typically plastic, but Lloyds A1 certification requires all through hull valves to be fire proof. Fireproof valves are typically 316L. I have purchased all my valves from the chemical industry. I have been told that urine will corrode 316 over time. I don't believe it. If 316 is good enough for corrosives in industry, why would it not stand up to human waste? If anybody knows for sure, please let me know. Steve There was a thread on rec.boats.cruising today in which a lady named Peggie Hall states: ---------------------------------------------------------------------------------------------------------- SS fittings in the sanitation system plumbing??? Not a good choice, 'cuz urine will corrode 'em. At least one trawler mfr who puts all fittings on the top of the tank, with a pickup tube inside the tank on the discharge (a great idea) used stainless fittings and pickup tubes--a VERY bad idea, 'cuz the tubes are corroding, even falling off in pieces inside the tank, in just a few years. -- Peggie ---------- Peggie Hall Specializing in marine sanitation since 1987 Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and Other Sources of Aggravation and Odor" http://shop.sailboatowners.com/boat_odors/ --------------------------------------------------------------------------------------------------------- Peggie has been posting on rbc for some years now and her posts have always been logical and informative. You might try contacting her for additional information. Bruce-in-Bangkok (correct Address is bpaige125atgmaildotcom) Bruce-in-Bangkok (correct Address is bpaige125atgmaildotcom) |
#12
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Calling all you chemists...
Nuclear subs have Titanium or K-500 Monel hull fittings. Are either of
these affordable for the rest of us? |
#13
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Calling all you chemists...
For all of you following this thread. The response from Sharpe Valves, maker
of these valves is below: Steve, everything we have says that 316 SS gets an "Excellent" or "A" rating when it comes to urine up to 140deg.F. Thanks, Pat Thank you all for your help. Steve "Steve Lusardi" wrote in message ... Will urine ie human waste corrode 316L valves and pipe? The question is asked because waste tanks are typically plastic, but Lloyds A1 certification requires all through hull valves to be fire proof. Fireproof valves are typically 316L. I have purchased all my valves from the chemical industry. I have been told that urine will corrode 316 over time. I don't believe it. If 316 is good enough for corrosives in industry, why would it not stand up to human waste? If anybody knows for sure, please let me know. Steve |
#14
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Calling all you chemists...
"Steve Lusardi" wrote in
: For all of you following this thread. The response from Sharpe Valves, maker of these valves is below: Steve, everything we have says that 316 SS gets an "Excellent" or "A" rating when it comes to urine up to 140deg.F. snip If you're ****ing out 140deg plus urine I'd say you'd be having bigger problems than a bit of corrosion in a fitting..... Bill |
#15
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Calling all you chemists...
Bill wrote: "Steve Lusardi" wrote in : For all of you following this thread. The response from Sharpe Valves, maker of these valves is below: Steve, everything we have says that 316 SS gets an "Excellent" or "A" rating when it comes to urine up to 140deg.F. snip If you're ****ing out 140deg plus urine I'd say you'd be having bigger problems than a bit of corrosion in a fitting..... Bill Too much hot sause on 'Mexican Food' nights? ;-) -- http://improve-usenet.org/index.html Use any search engine other than Google till they stop polluting USENET with porn and junk commercial SPAM If you have broadband, your ISP may have a NNTP news server included in your account: http://www.usenettools.net/ISP.htm |
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