Lubrication in ice. ppt 4 [autosaved]

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MARINE INT. COMB. ENGINES
Semester VI - UG11T3602
Lubrication in Marine I C E.
PPT 4
S K Mukherjee,
Faculty – IMU – KC.

Marine Int. Comb. Engines - II
 Basic Lubrication of Machinery.
 All machinery which have rubbing, rotating, and
rolling contact surfaces require a lubricating
medium in between.
 The lubricating oil in a machine unit is akin to
the blood system in a human body. For a
machinery system to run satisfactorily the
lubricating oil has to be at the highest level of
purity, cleanliness and appropriate viscosity.
Engine health condition and faults can be traced;
and impending issues can be diagnosed through
lub oil sample analysis.
 The principal functions of the engine lubricant
are as follows:

Basic Functions of a Lubricant/Oil.
 Lubrication - Provide a film between moving parts
and thereby reduce frictional resistance..
 Cooling - Heat transfer media. Removes/dissipates
the heat generated.
 Sealing - Filling in uneven surfaces. (example:
between piston ring & liner)
 Cleaning – Removing dirt, carbon, debris from
settling, and holding contaminants in suspension.
 Dampening & Cushioning - Of components under
vibration induced stress.
 Protection - From oxidation & corrosion
 Transporting - dirt and debris to cleaning systems
(filters & centrifuges).

 Good practices in machinery lubrication:
 a) Correct choice of a lubricating oil/lubricant
for the work it is intended. (i.e. Grade of Oil,
and associated properties)
b) Optimum feed rate as required . (Too much
oil is as detrimental as too little)
c) periodic checking/testing/analysis of the
used oil to determine the loss in characteristics
as compared to the new oil. And assess, if the
oil can continue in service OR requires to be
changed. It also finds faults within the engine.

 Lubrication of the main propulsion engines(2-St)
comprise of the following areas :
 1. Main system lubrication inside the crankcase.
(bearings/camshaft/gear and chain drives/exh v/v
operation etc)
2. Cylinder lubrication ( between piston rings
and Cylinder liner).
3. Miscellaneous areas such as Governor, Turning
gear, Turbochargers bearings (sometimes).

 Main Engine Lubricating oil system (ref : Diagram)
 The main or crankcase lubrication system is supplied by
one of two helical gear pumps, one of which will be
operating and the other is on standby, set for automatic
cut-in should there be a lubricating oil pressure reduction
or primary pump failure. The main LO pumps take their
suction from the main engine sump tank and discharge oil
via the main LO cooler, which takes away the heat. A fine
filter (50 um) , unit with a magnetic core helps to remove
any debris and traps ferrous particles for analysis. The tube
nest or plate-type LO cooler is cooled from the low
temperature central cooling freshwater system, and in
some cases directly by sea water

Main Engine Lub
Oil System.
1. From sump to
Engine parts and
return.
2. From sump to T/C
tk to T/c and back.
3. From sump to
Purifier and return.
4. From sump to Dirty
Oil Tk (DOT)
(through
pump/purifier)

• The supply pressure in the main lubrication system
depends on the design and requirement and is generally
around 4-6 kg/cm2.
• LO supply to the cooler is via a three-way valve which
enables some oil to bypass the cooler. The three-way valve
maintains a temperature of 40°C at the lubricating oil inlet
to the engine.
• The main LO system supplies oil to main bearings,
camshaft and camshaft drive, cross-head, guides, thrust
bearings, (piston cooling- if oil cooled,) & reversing
mechanism .
• Also provides for cut-out for monitoring devices to protect
engine against lub oil pressure drop or failure.

• Main Engine LO purifier takes suction from main engine
LO sump and purifies the oil. Its feed temperature is
maintained around 75-80 degrees Celsius (as maximum
density difference is achieved at that temperature) to allow
efficient separation.
• The engine LO must be tested frequently in order to
determine whether or not it is fit for further service.
• Samples should be taken from the circulating oil and not
directly from the sump tank.

Main Engine Lube Oil Sump Tank:
• It is located under the engine in the double bottom
(above the hull plate) and is surrounded by cofferdams.
• A sounding pipe to know the level of lube oil in the sump
is provided, along with a sounding pipe for cofferdam to
know if there is any leakage.
• Cofferdam needs to be inspected on regular basis to
know any signs of leakages.
• The main engine Lube oil sump tank consists of a level
gauge, sounding pipe, air vent pipe, heating steam coil,
manholes with covers, suction pipe with valves for LO
pump and LO purifiers.

 Turbocharger Lubricating oil system
 The turbocharger bearing lub system can be completely
separate from the main engine lub system or can be fed through
the main engine lubricating system (as in diagram), depending
on the design.
 The figure shows an arrangement to provide lub oil to the T/C
even when the engine is stopped, but with the LO pumps
running. It consists of an overhead tank filled with oil from the
LO pumps. A pipe from bottom of the tank with an orifice plate
leads to the T/C bearings, and thereafter to the sump tank. The
orifice plate allows flow at a lesser rate than the filling pipe.
Thus an overflow outlet pipe at the top allows the excess oil
collected to return to the sump tank. As the rotor of the T/C
continues to rotate for some time after engine is stopped it
requires oil for the bearings. The oil tank ensures this even if the
engine and pump have stopped or tripped inadvertently.

 Contaminants found in the System oil of a Two-
Stroke propulsion engine:
 1. Water (SW or FW). (max permitted: 0.2%)
2. Fuel( “Dilution”).
3. Cylinder oil (cylinder oil passing through stuffing box
into crankcase lub oil is a contaminant)
4. Carbonaceous products of combustion.
5. Insolubles. (dust, rust, worn metal particles, ash etc)
6. Microbial contamination (growth of Fungus).

Contamination of Lubricating Oil by Water
 Causes
 Leakages from cylinder cooling water system. Rare, as
design restricts such contamination. (FW)
 Leakages from piston cooling water system (for water
cooled pistons) quite rare as design restricts such.(FW)
 LO cooler water leakages (can be seawater or
freshwater).(Only while pump is running!)
 Leakages from sump tank heating coils.
 Condensation of water vapour inside crankcase.
 Centrifugal purifier incorrect operation. This is the most
common factor in water contamination

 Effects (water contamination)
 Acid formation in lube oil for trunk type piston engines.
 Reduction in cooling efficiency.
 Reduction in load carrying capacity of lube oil.
 Reduction in lube oil properties such as BN.
 Formation of sludge.
 Corrosion in various parts of the machinery.
 Microbial degradation of lube oil.

How to Deal With Seawater Contamination in Lube Oil
 Find and rectify source of SW/FW leakages immediately.
 Transfer whole sump oil to LO dirty oil/settling tank, maintain
temperature around 75-80 degree Celsius, drain water and
sludge periodically.
 Clean the sump of sludge and debris , and inspect.
 Run LO purifier in batch operation at about 78 degree Celsius
and optimum efficiency, from LO dirty oil/settling tank to tank.
 Send purified LO sample for shore analysis.
 Shore analysis report will specify whether the LO can be reused
or treatment such as water washing to be carried out or not.
 Return oil to sump after satisfactory report. Else, renew oil.

Allowable Limits for Water in Lube Oil
 For cross-head type engines water in LO to be less than
0.2%; take immediate action when the water content
reaches 0.15%; water content. Above this may damage the
engine.
 For trunk type engines water in LO to be less than 0.15%;
take immediate action when the water content is
above 0.1% ; water content above this may damage the
engine.

2. Fuel Dilution
 Causes
When unburned diesel fuel makes its way past the
rings and into the engine oil in the crankcase, fuel
contamination, or fuel dilution, results. Fuel dilution
can decrease oil viscosity and lubricity even at very low
levels, increasing both bearing wear and the potential
for bearing failure.
 In 4-St engines, fracture of fuel pipe to injector is a
common source of dilution.
 Leaking fuel pumps can cause fuel ingress into
camshaft spaces and thence to lub-oil system.

• Detection
Even a moderate decrease in oil viscosity can indicate the
presence of fuel contamination. As testing for fuel dilution
is the measurement of one petroleum product within
another, it is most accurately identified by gas
chromatography (GC), a process that separates the
mixture by vaporizing the sample and measuring each
component released.
• On board, unusual drop in L.O. pressure is indicative.
• Odors of Fuel & L.O. are distinctive and indicative. Sample
of LO can be checked through smell.
• Change in Flash Point is indicative and requires oil
change if below 180deg Celsius.

• Risk
• Fuel contamination is a serious issue that makes early
detection vital to maintaining component health.
• As diesel fuel lowers oil viscosity, it reduces the corrosion
protection of Lub oil , additives and accelerates
component wear.
• Extremely severe cases can result in a crankcase explosion
as Flash Point will have reduced.

3. Cylinder Oil
 Causes: Leakages past stuffing box (piston rod gland) will
result in the partly burnt, carbonized cylinder oil sludge
from under piston space to enter crankcase spaces and
contaminate the system oil.
 The mixing of cyl oil and system oil changes the viscosity
as well as the BN value to upset the normal requirements
in bearing lubrication. Damage results.
4. Carbonaceous products of combustion.
 Combustion debris, ash, Oxides of Vanadium, Salts of
Calcium, unburnt fuel, carbon generally arise through
leakages past the stuffing box when piston rings are worn
and blow past takes place

 5. Insolubles (Abrasives)
Causes
• Of these six contaminants, abrasives are, by far, the most
damaging to lubrication systems and engine
components.
• Common abrasives, in the form of dust and dirt, can
enter the lubrication system through leaks in the air
intake system, seals, ventilation system or from a
contaminated supply of new oil.
• As they circulate within the oil, they cause wear to metal
components, which can produce additional wear
particles that may cause even greater damage.

 Detectionn (OF Abrasives)
Concentrations of silicon and aluminum identified by ICP
(inductively-coupled plasma) spectroscopy are typically
indicative of dust and dirt contamination. ICP detects
wear, contaminant and additive elements present in oil by
ionizing the sample and using a mass spectrometer to
measure levels of concentration.
 Risk
If abrasive contaminants are left unchecked, extensive,
sometimes irreparable, engine and component wear can
occur reducing vehicle reliability and longevity and
increasing maintenance, repair and replacement costs

 6. Microbial Contamination
 Minute micro organisms in oils
 Minute microorganisms, i.e. bacteria, can exist in lubricating
oils and fuel oils. Under suitable conditions they can grow and
multiply at phenomenal rates. Their presence leads to the
formation of acids and sludge, metal staining, deposits and
serious corrosion. The presence of slime and the smell of rotten
eggs (hydrogen sulphide) indicates a contaminated system.
 Water in a lubricating oil or fuel oil, oxygen and appropriate
temperature conditions will result in the growth of bacteria and
infestation of a system. The removal of water, or ensuring its
presence is at a minimum, is the best method of infestation
prevention. The higher the temperature in settling, service and
drain tanks holding fuel or lubricating oils, the better.

 Coolers – (Heat Exchangers)
 The heat exchangers largely used on ships are:
 a) Shell & Tube type,
b) Plate Type

 Shell & Tube type: Casing is usually made of cloise
grained cast iron. Gun metal or fabricated steel may also be
used. End boxes are of the same material internally lined
with a rubber or epoxy compound. Sacrificial zinc anodes
are fitted as shown to prevent corrosion.
 The tube stack is made of stress relieved aluminium brass
tubes expanded into naval brass tube plates. One end is
fixed the other is free to expand as shown. Brass circular
baffles give radial flow to the fluid and support to the tube
stack.

PLATE
TYPE Heat
Exchangers
:

 Plate Type : Consists of a variable number of titanium (or
stainless steel or aluminium brass) plates clamped together
between a closing pressure plate and a frame as shown. Sealing
nitrile rubber in grooves is used between individual plates.
Plate surfaces are corrugated to give strength and increased heat
transfer surface. The corrugations are of herring bone design
with the “V” pointing up and down alternatively.
 Advantages:
 1. Compact and space saving. 2. Easily inspected and cleaned.
All pipe connections are at the frame plate so do not have to be
disturbed when plates are dismantled. 3. Variable capacity.
Number of plates can be changed to meet capacity
requirements.4. With titanium plates there is virtually no
corrosion or erosion risk and turbulent flow takes place
between plates to increase heat transfer and enable fewer plates
to be used.

Cylinder Lubrication
 The main purposes of providing lubrication between liner
and piston rings are:
 1. To separate sliding surfaces with an unbroken oil film.
2. To form an effective se4al between liner and rings to
avoid blow past of gases.
3.To neutralize corrosive combustion products and thus
protect liner, piston and rings from corrosive attack.
4. To soften deposits and thus prevent wear due to
abrasion.
5. To remove deposits to prevent seizure of piston rings
and keep engine clean.
6. To cool hot surfaces without burning.

Effects of excess cylinder liner lubrication
 Fouling of ring grooves and resulting ring zone
deposits.
 Consequently, loss of gas sealing effect and blow by
follows.
 Fouling of scavenge space and scavenge fire follows.
 Also affecting combustion process.
 Leading to breakage of piston rings
 Fouling of exhaust system and
turbocharger.
 Increased cylinder oil consumption.

Effects of reduced cylinder liner lubrication ?
 Promotes wear of liner and rings
 Overheating of local area resulting micro
seizure due to lack of boundary lubrication.
 Consequently major damage to piston and
cylinder liner.
 Increased blow past with potential for scavenge
fires with related damage to the engine as
whole.

Grade of Oil used: (for Cylinder Liner)
 The oil used for cylinder lubrication in 2-st engines is
SAE-50 (Society of Automotive Engineers, ‘50’ is the grade
Viscosity at stipulated temperature). The oil further
requires a base (Alkali content) to neutralize the acidic
component of the exhaust gases arising out of the sulphur
in the fuel. The strength of the alkali is indicated by the
Total Base Number (TBN) or presently just ‘BN’ . With
high Sulphur content of 3-3.5% the base number is 70. ie:
’70 mg of alkali in one gram of the oil’. The crank-case or
System oil is generally SAE-30 or SAE – 40. Care must be
taken not to allow the two oils to mix.

Cylinder Liner Wear:
Types of wear: 1. Abrasive wear,
2. Corrosive wear.
 Abrasive wear: occurs when abrasive particles enter the
combustion spaces with scavenge air or as a result of poor
quality or contaminated fuel. Instances of extremely high
abrasive rates can be caused by catalytic fines or “Catfines”.
These are products in residual fuel: Al2O3, and SiO2.
• Corrosive Wear: This is the more common cause of cylinder
liner wear, caused when burning heavy fuel containing sulphur.
During combustion this forms SO2 & SO3, ie Sulphuric &
sulphurous acids in combination with the water vapour which is
also a product of hydrocarbon combustion. This necessitates
use of alkaline lub oils for cylinder lubrication

“Clover-leafing”:
 This form of liner wear occurs when the alkali strength
does not commensurate with the sulphur concentration in
the fuel. Lower than required level of BN will cause uneven
wear along the length of the liner walls. The
circumferential profile partly resembles a clover leaf.
Ineffective sealing between ring & liner results, thereby
cause for ‘collapse’ of rings, & blowpast.

CLOVER –LEAFING OF Cyl Liner.
Wear pattern in Cyl Liners:

“Bore-Polishing” :
 This arises if the alkali strength is more than requirement,
then deposits of CaCO3/CaSO4 on the topland will cause
the salts to reach the spaces between the top ring and liner.
This as an abrasive will cause polishing of the liner surface,
thereby reducing the ability of surface oil retention.
Enhanced wear down with blowpast results. Anti-
Polishing Rings (APR) are used for prevention of such
wear. Also called ‘piston-cleaning-rings’.

ANTI-POLISHING RING for Cylinder Liners

Fitting of APR…
Accumulation of comb. debris &
salts…

Importance of Lubricating Oils:
 The most essential fluid that is used in an engine, is the
lubricating medium – the oil. The engine oil is the main
lubricant that plays a vital role in the engine cycle.
Viscosity is the MOST IMPORTANT property of the
lubricating oil. Vital functions of the oil are as stated
below:
 The engine oil reduces the friction among the parts of the
engine at the various stages of the combustion cycle
reducing the wear and tear of the internal parts of the
engine.
 The engine oil performs the vital role of cleaning the
sludge from the engine block which would otherwise result
in a possible blockage

 The engine oil helps neutralise the acids that
are released at any stage of the combustion
process from the fuel and oxidation of other
lubricants.
 The engine oils also have anti-corrosion abilities
which prevent the cylinder block from getting
corroded.
 The engine oil carries away the heat generated
between running surfaces and keeps
components cool.

 ENGINE OIL GRADES….Introduction
Lubricating Oils in Engines can be of various VISCOSITIES.
This property is the key factor in ensuring satisfactory
health, running conditions and clearances between contact
surfaces in all parts of the machinery.
Lubricating oils principally come in two grades: Monograde
oils and Multigrade oils. Further, SAE (Society of
Automotive Engineers) identify oils as “Summer” grades
and “W” – Winter grades. The Summer grades are more
viscous or ‘thicker’ oils, and the Winter grades are less
viscous or ‘thin’ oils. While ‘Monograde’ is a single
Summer OR Winter oil, ‘Multigrade’ is a combination of
the Summer & Winter grades

• Engine oils:’Summer’ & ‘Winter’ are differentiated on
the basis of their viscosities. Different engine oils
have different viscosities at room temperature and also
react differently to temperature changes.
• Selecting an engine oil grade is based on design,
running conditions such as temperature limitations,
loading of the components, surface speeds,
dimensions, clearances and more.
• When an engine starts the oil is cold and thick and
requires a thin oil. After a period of running as the oil
heats up it becomes thinner.

Reqirement is an optimum value of viscosity at normal
load condition. This calls for a combination of the S &
W oils. The S-oil simply is denoted by its viscosity
grade number while W-oils use the letter”W”.
Therefore, there is one set (W) which measures cold
temperature performance (0W, 5W, 10W, 15W and
20W). The second set (S)of measurements is for high
temperature performance (8, 12, 16, 20, 30, 40, 50)

 What does 20W-40 mean in engine oil?
 The engine oil grade consists of 4 characters. Here we explain
the meaning of each of them:
 The first number is followed by a ‘W’. Here the W stands for
Winter and represents how the oil will react to a cold start.
 In simple words, the number with the W represents the
parameter of how the oil will flow in cold conditions.
 The smaller the number, the better will be the flow. For
instance, a 5W-30 oil will have a better cold flow than 10W-30
engine oil.
 The number in the following part is the indication of how the
finely the oil will flow at normal operating temperature once it
is achieved.
 The 10W-30 engine oil will have a better flow than the 10W-40
engine oil at normal operating temperature

Marine Int Comb. Engines - II
 What are the types of engine oils?
 In general, there are three types of engine oil:
 Mineral Engine Oil:
This is the most basic lubricating oil. Mineral oils are
refined petroleum oils from crude oils, and which
undergo treatment to function under a wide
temperature range. These are cheaper than the other
two.
Mineral oils find their use in older 2-Stroke Diesel
engines, sometimes with additives (Anti-rust, and anti-
oxidation), and in 4-stoke diesels with detergency,
dispersancy and low alkalinity.

Semi-Synthetic Engine Oil:
 This is one diplomatic engine oil. It positions
itself right in between the territory of Mineral
and Full Synthetic oil. As easy to say, Semi-
Synthetic oil is a combination which offers the
affordability of mineral and the performance of
synthetic.
Semi-synthetic offer as much as three times
the protection compared to mineral oils. The
drawback with semi-synthetic is that they do
not offer the superior level of protection that a
full synthetic does.

 Full Synthetic Engine Oil
 The cutting edge in engine oil technology. Full
synthetic engine oil delivers excellent protection and
aides in better fuel efficiency. They are very costly
 Synthetic oils go through extensive treatment in the
lab to make them significantly superior to their
counterparts. The process involves breaking down
the mineral oil into the most basic molecules, which
helps remove any undesired substances and
impurities to a very high degree. The molecules of
synthetic oil are also very consistent in their size and
shape, offering superior lubrication. Full synthetic
oil function at their optimum in both low or high
temperatures, or under extraordinary stress.

 ADDITIVES in Lubricating oils:
• There is more to lubricants than just
viscosity. Additives are chemical compounds
which are added to improve protection of
components and increased life of the oil by
giving:
a) properties which the oil does not have,
b) replacing desirable properties that may
have been removed during refining,
c) enhancing the performance of the basic
lubricating oil.

 Additives have three basic roles:
 Enhance existing base oil properties with
antioxidants, corrosion inhibitors, anti-foam
agents and demulsifying agents.
 Suppress undesirable base oil
properties with pour-point depressants
and viscosity index (VI) improvers.
 Impart new properties to base oils with
extreme pressure (EP) additives, detergents,
metal deactivators and tackiness agents.

 Types of additives:
 1. Anti Oxidant.
 2.Corrosion Inhibitors,
 3. Detergency
 4 Dispersancy,
 5. Pour point depressants,
 6. Viscosity-Index improver.
 7. antifoaming additives,
 8.Oiliness and extreme pressure additives

THANK YOU
S K Mukherjee,
Faculty, IMU- Kolkata Campus.

Lubrication in ice. ppt 4 [autosaved]

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