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

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

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

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

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)

"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.

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

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

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

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)

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)

Nuclear subs have Titanium or K-500 Monel hull fittings. Are either of
these affordable for the rest of us?

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

"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

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? ;-)


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