It is amazing how brand new ships are destroyed in a single year by ship staff who have NO dang idea about destructive properties of cavitation.
Here are some actual emails-- glean from it and be safe!
It gives me no pleasure to post this email.
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A05768 Mon, 8 Dec XXX 07:20
From: XXXR - Master
Date: Sunday, December 07, XXX 7:44 PM Msg: A05768-65626
Path: \XXXX - MASTER\ SENTBOX
gentlemen,
let's get scientific--
HOW THE COOLER TUBES GET HOLED !!
bernoulli lifted his law from 6 millenium old indian science of yoga.
in preparation for his routine pranayama to boost nitric oxide levels
and hence the oxygen intake -- the yogi must first clear his sinuses--
he would drink saline warm water through his nose ( driving water with
great force ) first thing in the morning. the capillary eductor action
sucked out the mucous from the sinuses- and the muck came out though the
mouth , along with the driving water.
bernoulli's law stated that, if an inviscid fluid flows along a pipe of
varying cross section, then the pressure is relatively low at
constrictions where the velocity is high and relatively high where the
pipe opens out and the fluid stagnates.
now this is surely a paradox--- for to a not so bright layman -- a
constriction should increase the local pressure rather than diminish it.
the paradox is solved when you term pressure changes along the pipe as
cause and the velocity changes as effect, instead of the other way
around.
here is a simple experiment . hold two sheets of A4 size paper so that
they hang vertically two centimetres apart and blow downward so that
there is a current of air between them. the sheets will be drawn
together by the reduction in pressure associated with this current.
ships are drawn together for much the same reason if they are moving
through the water in the same direction at the same speed with a small
distance between them.
now---other simple experiment, go to the toilet and listen to the
hissing sound made by a tap that is almost shut. the flow is so
constricted and the velocity within the constriction so high that the
pressure in the constriction is actually negative . the water cavitates
as it passes through, as the liquid pressure drops below vapour
pressure. the crackling noise that is heard is the sound of tiny
bubbles collapsing ( implosion ) as the water slows down and the
pressure rises again on the other side.
this scours the metal away like grit blasting- at constrictions and
bends --- no zinc anode can stop it..
best regards
capt ajit vadakayil
master
XXX
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dear XXX,
NOTE: ON ALL XXX SHIPS-- ZINC ANODES ARE ERODED AND
COOLER TUBES ARE HOLED -- NOT BY GALVANIC CORROSION
--BUT BY CAVITATION!--
COOLER TUBES ARE HOLED -- NOT BY GALVANIC CORROSION
--BUT BY CAVITATION!--
-- BECAUSE OF LACK OF UNDERSTANDING--
COOLING WATER INLET MUST BE 100% OPEN ALWAYS -- OUTLET
MUST BE THROTTLED TO CONTROL TEMP AND REDUCE FLOW
MUST BE THROTTLED TO CONTROL TEMP AND REDUCE FLOW
FOR GALVANIC ACTION ON ZINC TO TAKE PLACE ELECTROLYTE
SEAWATER MUST BE STAGNANT --THAT IS WHY WHEN WE BALLAST
SS TANKS , SALT WATER IS RECIRCULATED.
SEAWATER MUST BE STAGNANT --THAT IS WHY WHEN WE BALLAST
SS TANKS , SALT WATER IS RECIRCULATED.
try shaking your car battery vigorously-- it wont retain charge!
brgds
capt ajit vadakayil
master
#######################
-----
From: XXXX - MASTER
Date: Thu, 5 Aug XXX 03:30 +0100 Msg: A03153-15578
Subject: Re: TECH2/ EXIT INERTIAL CAVITATION AND RED WATER
dear XXX,
XXX needs to have some intelligent " physics party " along with
their motley " chemical party " .
the trouble with them is they have the blinkers on, on the chemical
tunnel trial.
CHEMISTRY is about nitrite corrosion inhibitor, hardness, chlorides,
wildly fluctuating pH, scaling , galvanic corrosion , bacteria chomping
of nitrites , passivating films etc.-- CURES
PHYSICS is about cavitation, nucleating surfaces , de-aeriation from
ford end of engine, air/steam finding the highest point, expansion
tanks, inclination of jcfw outlet pipe, thermal expansion of metals ,
oxygen scavenging by heat , dynamic stresses etc -- PREVENTION
i guess PREVENTION IS BETTER THAN CURE.
nitrite passivating films protects only anodic mild steel from giving up
electrons. azole protects copper. galvanic corrosion returns metals to
their element state on the periodic table of medeleyeev.
in the tunnel trail with descaling acids they don't realise that zinc
galvanised coatings ( economy ships , ney ) cannot take pH value outside
6 to 9 range.
a proper deareating cyclonic tank, in the JCW system inserted into the
piping , with an alarm in case of excess steam formation can do wonders.
thermostatically controlled regulating JCW valve seat is the perfect
area for nucleations by local steam formation and local overheating .
digression: given the chance XXX will come hoppety hop on XXX
with diesel guard nb and rcor nb in their back packs , to get rid
of our RED water woes ( kiss our kidneys goodbye! ) -- by passivating
our mild steel fw pipe interiors--
-- like how the cancer doctor puts his hooks on the cancer patient and
bleeds him till he dies.
brgds
capt. ajit vadakayil
MASTER
#########################
-----Original Message-----
From: XXXX - MASTER [mailto: XXX.com]
Sent: August 05, XXX 1:00 AM
dear XXX,
i have to break a promise about long engineering emails --- such is the
importance to safety and economy -
a month back i had sent a email to you/ XXX, about RED domestic fresh
water water woes.
i had explained how our cold toilet fresh water water MS pipes rusty and
pitted from inside , but shining SILVER on outside ( japanese economy
ship--ney! ) -- produces red water by DISCHARGE CAVITATION TRRRRRR -.
this was after i read with a lot of amusement-- everybody's collective
ridiculous take on this matter , over the past 2 years on emails --
( with XXX all gassed up and revved to milk the shipowners with MORE
fantastic but costly chemicals, and poison poor sailors' kidneys -- )
today, i am in the mood to expound further--
first check out the attachments --
both are as different as salt and sugar.
one is affected by INERTIAL cavitation while the other by NON-INERTIAL
cavitation.
one is a LOW PRESSURE area handling minus 0.3 bars pressure ( vacuum )
while the other is a HIGH PRESSURE area handling + 7 bars pressure--always .
OUR BUDGET LOSS DUE TO CAVITATION OF EMS BRAND NEW SHIPS HAS BEEN
FANTASTIC --
COOLERS ETC COST MONEY -- but we do mindless cure , with NEVER a thought
given to prevention--
i will only talk about TRRRRR discharge cavitation here--
-- the picture is of a recirculation octopus which always hold minimum 7
bars pressure of hot water and tank cleaning chemical solvent.
the hole have been created by a few hours of TRRRR on a strong metal --
not a lifetime
when fluid pressure falls < SVP ( a value based on tensile flow ) caused
by EXIT CAVITATION , in areas where fluid flowing along a wall a high
pressure detaches itself-- we get holes.
it is about fluid dynamics -- at branches , ( flow velocity is
disregarded by design engineers )--where bubbles implode after
nucleating against a focused ratio of flow to area surface.
when water changes its state from liquid to gas its volume increases by
1700 times approx.
at the junction the vapor is compressed back into liquid ( as the
tank cleaning machine orifice is small ) creating an unequal formation--
at this junction you can hear sound. this is due to play of VP/ BP /
volatility of the solvent + water mixture.
( digression: in the holly wood movie chain reaction starring morgan
freeman --they add argon to the water before cavitating the blue water
to generate unlimited free energy from ZPE -- a must see!! )
bottom line: most of our brand new chemical tankers will require
extensive renewals of ER under bilge pipelines --due to inertial
cavitation. no cathelco or aluminium hydroxide gel can stop it.
3 of my personal friends on different ships in different companies did
ABANDON SHIP at sea because of TRRRR effect in engine room sw pipes.
brgds
capt. ajit vadakayil
MASTER
XXXX
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-----
From: XXX MASTER
Date: Thu, 21 Oct XXX 16:53 +0100 Msg: A03153-26377
gentlemen,
excessive iron in drinking water causes kidney and liver problems.
SMS 10c of 2010- RED WATER -- SEAFARERS RIGHT UNDER ILO-MLC-2006 TO
CLEAN WATER AND ADHERENCE TO XXX POLICY REGARDING CREW HEALTH
The fresh water pipes in accomodation have lost their inner coating and
are poor quality ( though looking good on outside ) leaching RED rust
water .
this problem is worsened when shore fresh water is taken which has high
dissolved oxygen compared to ships generated distilled water.
This rusty fresh water affects the quality of crew’s life on board and
their health.
This is in contravention of ILO- MLC-2006 guidelines ( for which all
ships will have to be mandatorily certificated soon ) and XXX company
policy regarding crew health.
Budget constraints are hence overridden .
This rust water settles down on all the white cement between toilet
galley tiles and gives them a dirty look- affecting the first impression
of any inspector.
This dirty grooving cannot be removed by any amount of scrubbing , which
only makes the grooves more deep. They have to be soaked in phosphoric
acid and then washed down to get back the original white colour.
The crew keeps fresh water taps open to reduce the red water intensity
wasting about 20% of the water .
This must be balances with the economics to find a solution in
conjunction with owners.
Rust water does has reactions with crew skins- and it is commonplace for
crew to get boils and carbuncles-which can be explained by any doctor.
At the end of a contact officers are forced to discard all their
expensive good clothes on board which have the discoloured brown jaded
look and cannot be worn ashore in any decent place. This is due to
laundry machine taking in red water-which cannot be drained initially.
THE SOLUTION IS TO IDENTIFY THE SHIPS WITH THIS PROBLEM AND
REPLACE THE FW PIPES WITH PVC PIPES .
There is a school of thought that PVC pipes will rupture in a fire OR
give toxic fumes. These fears are unfounded.
You can keep a paper cup filled with water in a microwave and turn on
full heat-the cup will NOT catch fire as long as there is water inside.
Water has the following properties:--
----Large heat capacity. It requires lot of energy to increase its
temperature .
----Large latent heat of vaporization . It requires 5 times more energy
to convert boiling water to steam
----High thermal conductivity
If a ship’s accommodation catches fire, the topmost tap in the bridge
toilet can be left 20% open-and the PVC pipes are safe from rupture or
from emitting toxic fumes.
In freezing weather a thin pipe from topmost FW pipe leading back to
fresh water tank will prevent any rupture. However freezing rupture is
more applicable to metal pipes-as PVC pipes will squirt from joint
rather than rupture.
PVC pipe replacement is an UNSKILLED job.
brgds
capt. ajit vadakayil
MASTER
XXX
" motivation comes from within-- happiness too! "
email: XXX.com
CAPT AJIT VADAKAYIL
..
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