guidance for lubricating oil management
TRANSCRIPT
-
7/26/2019 Guidance for Lubricating Oil Management
1/29
Copyright 2003 by NYK LINE All rights reserved
Guidance for Lubricating Oil Management
(Main Engine System Oil)
2003
NYK Line
Technical Group
Maritime Technology Team
-
7/26/2019 Guidance for Lubricating Oil Management
2/29
Copyright 2003 by NYK LINE All rights reservedi
Table of contents
Introduction .......................................................................................................................... 1
Chapter 1: System Oil Management for Slow-Speed Engines .............. .............. ............. ..... 2
1. Characteristics of system oil for slow-speed engines.........................................................2 2. Balance of system oil circulation .......................................................................................2
2.1 Lubricating oil for replenishment and drip oil entering system oil .................................3
2.2 Leaked lubricating oil and drawn out lubricating oil......................................................3 3. Onboard system oil management ......................................................................................4
3.1 Maintaining a proper amount of system oil...................................................................4 3.2 Maintaining properties of system oil ............................................................................43.3 Economical Efficiency .................................................................................................5 3.4 System oil analysis .....................................................................................................53.4.1 Purposes of system oil analysis................................................................................5
4. Standard Values for Lubricating Oil Management ..............................................................6 4.1 Standard Values for System Oil Management ..............................................................6
5. Items to be checked for system oil management ...............................................................9 5.1 Density .......................................................................................................................95.2 Kinematic Viscosity .....................................................................................................9
5.3 Flash Point..................................................................................................................95.4 Water Content .............................................................................................................9 5.5 TBN (Total Base Number)..........................................................................................10 5.6 TAN (Total Acid Number) ........................................................................................... 115.7 Insolubles ................................................................................................................. 115.8 Metal......................................................................................................................... 115.9 Ferrography .............................................................................................................. 11
Chapter 2: System Oil Management for Medium-Speed Engines................ .............. .......... 12
1. Characteristics of system oil for medium-speed engines .................................................12 2. Balance of system oil circulation .....................................................................................12
2.1 Lubricating oil for replenishment................................................................................122.2 Lubricating oil for consumption..................................................................................13
3. Onboard system oil management ....................................................................................13 3.1 Maintaining a proper amount of system oil.................................................................13 3.2 Maintaining properties of system oil ..........................................................................143.4 System oil analysis ...................................................................................................14
4. Standard Values for Lubricating Oil Management ............................................................16 4.1 Standard Values for System Oil Management ............................................................16
5. Items to be checked for system oil management .............................................................16 5.1 Density .....................................................................................................................165.2 Kinematic Viscosity ...................................................................................................16 5.3 Flash Point................................................................................................................17 5.4 Water Content ........................................................................................................... 175 .5 TBN (Total Base Number).........................................................................................185.6 TAN (Total Acid Number) ........................................................................................... 185.7 Insolubles .................................................................................................................18 5.8 Metal.........................................................................................................................18 5.9 Ferrography ..............................................................................................................18
Chapter3: Economical System Oil Management for Slow-Speed Engines .............. ............ 19
1. Replenishment method for system oil.............................................................................. 192. Replenishment with only new oil .....................................................................................19
2.1 Guide for implementation .......................................................................................... 193. Re-use of stuffing box leaked oil .....................................................................................19 4. Use of Low Viscosity Oil .................................................................................................21
4.1 Guide for implementation .......................................................................................... 214.2 Use of Low Viscosity Oil............................................................................................21
5. Replenishment ratio of recycling oil and low v iscosity oil .................................................22 5.1 Reuse of recycled oil (stuffing box leak oil)................................................................235.2 Make up with low viscosity oil ....................................................................................24 5.2 Make up with low viscosity oil ....................................................................................25
-
7/26/2019 Guidance for Lubricating Oil Management
3/29
Copyright 2003 by NYK LINE All rights reserved1
Introduction
With the ever-increasing degradation of marine fuel oil and the successive introduction of
high-output propulsion engines, system oil management for diesel engines has continued to undergo
gradual changes.
Although engine manufacturers, oil companies, and ship owners have established their own
standards for system oil management, some of their standards are merely specifications based on
their experience and have not been sufficiently examined from a technical point of view. For
slow-speed engines, it is necessary to adopt a management method in accordance with the actual
condition of system oil because contamination of used cylinder oil (the so-called drip oil) continually
increases with the adoption of high-power, supercharged engines. Meanwhile, for medium-speed
engines, more meticulous (careful) management is needed because system oil is directly affected by
combustion gas and/or ingress of combustion residues, which cause heavy fouling.
Therefore, standard values for system oil management are significantly affected by engine
design and the purification of lubricating oil, and it is presumed that this tendency will continue in
the future.
With such situation being prevalent, NYK has continuously conducted surveys on the properties
of system oil for main engines and has considered establishing an optimum system oil management
method capable of responding to changes in oil conditions.
This guidance explains the following items:
System Oil Management Method for Slow-Speed Engines
System Oil Management Method for Medium-Speed Engines
Items to be checked Limit values: The highest or the lowest value for use
Economical System Oil Management Method for Slow-Speed Engines
The purpose of this guidance is to provide an effective oil management system.
Needless to say, the major objective of lubricat ing oil management is to minimize engine
failures and to maintain safe operation of the vessels. In the meantime, we are required to maintain a
cost-conscious view and to strive to contribute to the economical operation of the ship by reducing
consumption of lubricating oil. Therefore, it is important to combine safe operation of vessels with
economical ship operation.
We hope this guidance will be used by all concerned for the consequent safe operation of
vessels.
-
7/26/2019 Guidance for Lubricating Oil Management
4/29
Copyright 2003 by NYK LINE All rights reserved2
Chapter 1: System Oil Management for Slow-Speed Engines
1. Characteristics of system oil for slow-speed engines
On two-stroke cycle slow-speed engines of the crosshead type (slow-speed engines) the cylinder
space and the crankcase are separated so that the system oil does not directly make contact with the
combustion chamber and the combustion gas. Cylinder oil, which is different from system oil, is fed
into the cylinder liners.
A characteristic of system oil for slow-speed engines is that a fouling continues as a result of the
ingress of used lubricating oil. Cylinder oil, after lubricating the cylinder liner, drops along the liner
wall and remains in the space under the piston. Some of the dropped cylinder oil mixes into the
system oil through the stuffing box. The amount of mixed cylinder oil depends upon the type of
engine and the maintenance conditions of the rings, however, in general the higher the turbocharging
and the greater the wear on the stuffing seal rings, the larger the amount of mixed cylinder oil.
The design of the stuffing box also has a significant effect on the amount of oil entering into the
system oil. Meanwhile, lubricating oils used in slow-speed engines (crosshead type) are rarely
affected by acid materials and/or oxidation.
Therefore, the main point of system oil management for slow-speed engines is to take measures
to prevent contamination by drip oil. More specifically, system oil management is to be carried out
by placing emphasis on changes in kinematic viscosity and TBN.
2. Balance of system oil circulation
A balance of system oil for slow-speed
engines is illustrated in Figure 1-1. The squares
with a solid line in Figure1-1 indicate lubricating
oils replenished or mixed into the circulating
system, while the squares with a dotted line
indicate lubricating oils leaked or drawn out
from the circulating system. The amount of
new oil / drip oil makes up for the quantity of
lubricating oil leaking/drawing out of the
circulation system and as a consequence the total
amount of system oil is usually maintained at the
same level.
On an older type of engine, the amount of
new oil is larger because the amount of drip oil is
relatively small. As a result, the properties of
system oil are almost the same as those of new oil. On the contrary, on a high-power,
high-supercharged engine, the amount of drip oil is large while the amount of new oil replenished is
small.
As a result, the properties of system oil will deteriorate compared to an older type of engine.In particular, when the values of kinematic viscosity and TBN increase significantly, drawing out of
system oil in use is needed.
Fig.1-1 Balance of system oil (Low-speed)
Lanternrecess drain
Otherleaked oil
Drip oil(Leaked oil)
Cylinder oilinjection
Drawingout
Sump Tank
Separatorleaked oil
Replenishment,
ContaminationLeakage, Drawing
Replenishmentof new oil
System
oilStorage
tank
Stuffing boxdrain
Separator
-
7/26/2019 Guidance for Lubricating Oil Management
5/29
Copyright 2003 by NYK LINE All rights reserved3
2.1 Lubricating oil for replenishment and drip oil entering system oil
(1) Replenishment New oil / Reuse oil
1) New oil is replenished at periodic intervals.
2) Reuse oil, drip oil leaked from the seal rings on the stuffing box, is sometimes used together
with new oil.
3) Ensure that enough new system oil, desirably the entire amount of system oil being circulated
that can be replaced at least once, is kept at all times in order to deal with any unexpected
accidents during which an entire amount of system oil would need to be replaced.
(2) Drip oil
1) This is the used lubricating oil entering the crankcase from the space under the piston through
the stuffing box seal rings.
2) The properties of drip oil vary with the type of engine and the cylinder feed oil ratio, however,
it is presumed that drip oil has almost the same property values of lantern drain oil, which are
shown in Table 1-2.
2.2 Leaked lubricating oil and drawn out lubricating oil
(1) Stuffing box leaked oil
1) This is leaked-off oil (used lubricating oil and system oil) from scraper rings on the stuffing box
and is led away to a drain.
2) Stuffing box leaked oil chiefly refers to system oil from the crankcase scraped off by the sets of
rings on the stuffing box and returned to the recycling tank. It has similar properties to the
original system oil as shown in Table 1-1.
3) Re-use may be possible for this oil after the oil has been treated in the purifier.
Table 1-1: Properties of Stuffing Box Leaked Oil and System Oil
Items
Density
(g/cm3)
Kinematic
Viscosity
(cSt @40)
Water
(%v/v)
TBN
(mgKOH/g)
Insolubles
in Pentane
(%m/m)
Leaked oil (range) 0.8865~0.9255 100~160 0.02~1.5 6.5~30 0.01~2.6
Leaked oil (average) 0.9064 126 0.20 16.5 0.33
System oil (average) 0.9041 123 0.14 14.4 0.11
(2) Lantern drain oil
1) This is the used lubricating oil (contaminated oil) remaining in the bottom of the scavenge
space, where it is drained away via the scavenge drains.
2) On modern engines the same drain line is generally used for the stuffing box leaked oil and the
lantern drain oil. In such a case, re-use is not possible for the stuffing box leaked oil.
Table 1-2: Properties of lantern drain oil
Items
Density
(g/cm3)
Kinematic
Viscosity(cSt @40)
Water
(%v/v)
TBN
(mgKOH/g)
Insolubles
in Pentane(%m/m)
Insolubles
in Toluene(%m/m)
Properties 0.948~0.966 185~300 0.5~1.0 48~60 1.5~2.5 0.5~2.0
-
7/26/2019 Guidance for Lubricating Oil Management
6/29
Copyright 2003 by NYK LINE All rights reserved4
(3) Drawn out system oil
1) When constant deterioration of the system oil is observed (when the amount of drip oil is large),
conduct drawing out operations at periodic intervals.
2) Temporary drawing out is an effective remedy for sudden deterioration in properties of the
system oil.
(4) Leaked-off oil from purifier
1) This is the lubricating oil drained out from the purifier when cleaning.
(5) Other leaked-off oil
1) This is the lubricating oil leaked from the flanges on the piping.
3. Onboard system oil management
3.1 Maintaining a proper amount of system oil
1) Carry out replenishment or drawing out in a timely manner to maintain a proper amount of
system oil at all times.
2) System oil tends to be affected by fouling when the total amount of system oil decreases.
3) In general the amount of system oil for low-speed engines is approximately 14m3 / 10000kw
(10m3 / 10000PS).
4) Attention should also be paid to the amount of new oil.
(Ensure that enough new system oil, desirably the entire amount of system oil being circulated
that can be replaced at least once, is kept at all times)
3.2 Maintaining properties of system oil
3.2.1 Replenishment and Drawing out
1) Carry out replenishment or drawing out in a timely manner to keep the property values of the oil
within the recommended standard values.
2) Determine the optimum amount of replenishment or drawing out based on the results of
periodic analysis.
3) Except in an emergency case, when the values of kinematic viscosity and TBN can be
maintained within the standard values, other properties can also maintained.
4) Properties of the system oil are affected to varying degrees by the engine load, wear on the seal
rings on the stuffing box, and the amount of cylinder feed oil. Therefore, these factors should be
taken into account when maintaining system oil.
3.2.2 Treatment by purifier
(1) Carry out system oil treatment with the purifier.
1) Bypass purifying
a. Set the oil flow rate for the purifier to approximately 1700 lit/h /10000kw(1300 lit/h/10000PS).
b. Set the oil flow temperature between 80 and 85.
c. For a total blow type purifier, set the cleaning interval to two hours or less because calcium
compound, a main ingredient in additives, is liable to become hard if two hours is exceeded.
(2) Entire quantity purifying
-
7/26/2019 Guidance for Lubricating Oil Management
7/29
Copyright 2003 by NYK LINE All rights reserved5
Treat all of the system oil during a docking period when the main engine is stopped for a
prolonged period of time.
a. Transfer all of the system oil to the lubricating oil settling tank and purify it by circulating it
through the purifier. In addition, clean the lube oil sump tank.
b. Set the heating temperature in the tank to approximately 80 .
c. The oil flow volume through the purifier is to be adjusted to between two and three times the
entire amount of system oil. (With 10m3 of system oil, for example, the oil flow volume would
be between 830 to 1250 lit/h)
3.3 Economical Efficiency
(1) New oil replenishment is to be minimized. The quality of the system oil can be maintained in optimum
condition if a larger amount of new oil is supplied, however, economical efficiency will be small.
(2) When considering economical efficiency, the target value should be close to the upper limit of the
standard value range. More meticulous management is required.
**** Target value for system oil management ****
a. Kinematic Viscosity: Upper limit minus 5 cSt
b. TBN : Upper limit minus 5 mgKOH/g
(3) Re-use of stuffing leaked oil is to be considered.
Re-use of stuffing leaked oil is available when values of system oil are kept with only new oil
replenishment. In this method, new oil must be used together with stuffing leaked oil.
Replenishment with only stuffing leaked oil should be avoided.
**** Guide line for stuffing leaked oil ****
a. Kinematic Viscosity: Upper limit minus 10 cSt
b. TBN : Upper limit minus 10 mgKOH/g
3.4 System oil analysis
1) Request shore laboratories to make analysis at regular intervals.
2) When conducting shipboard analysis, check the accuracy of shipboard analysis results by
comparing the results to shore analysis.
3.4.1 Purposes of system oil analysis
1) To determine whether the system oil is usable or not
2) To assess current conditions of the engine (for example, detection of abnormal wear on the
bear ing)
3) To review whether the management method for system oil is appropriate or not
3.4.2 Analysis interval
1) When no problem is observed: every six months or shorter2) When a problem occurs: during trouble and every one to three months after occurrence of the
trouble
-
7/26/2019 Guidance for Lubricating Oil Management
8/29
Copyright 2003 by NYK LINE All rights reserved6
3.4.2 Sampling
1) Samples (oil actually circulating through the system) are to be taken from the sampling cock or
the air vent valves on the cooler, the pump, and the filter.
2) Prepare a clean container for sampling.
3) Sampling is to be conducted after the drain is thoroughly discharged.
4) Usually the amount of the sample is 0.5 to 1 liter. (It depends on shore laboratories.)
5) In case of trouble, samples are to be taken at the inlet/outlet of the damaged components
(usually at the outlet of the pump). When a sample is taken at the outlet of the filter, wear
particles have been captured on the filter and the cause of the problem may not be identifi ed.
4. Standard Values for Lubricating Oil Management
The standard values which were used until recent years had been specified based on the balance
of system oil used for the older type of slow-speed engines.
Therefore, these values were determined from mere experience without technical examination.
If these values were applied to the system oil management for modern engines, uneconomical
management results would occur with large amounts of system oil drawn out and large amounts of
new oil supplied. Furthermore, even if an engine runs for a prolonged period of time with the system
oil exceeding the standard values, normal engine operation can be achieved without noticeable
problems. This has been verified by practical engine operat ions onboard. In this respect there is
still some margin to reduce new oil consumption of system oil.
More than 15 years have passed since the first high-output propulsion engine was introduced,
and only in recent years have manufacturers and oil companies prepared standard values for system
oil management for high-output propulsion engines.
However, since their standards include indefinite values, we decided to do better by reviewing
the standard values based on the results of past onboard surveys conducted by NYK.
4.1 Standard Values for System Oil Management
(two-stroke cycle slow-speed engines (crosshead type))
The NYK standard values for system oil management for two-stroke cycle slow-speed engines
(crosshead type) are shown in Table 1-3. The standard values (or recommended values) for system
oil management specified by the engine manufacturers and oil companies are shown in Table 4-1.
-
7/26/2019 Guidance for Lubricating Oil Management
9/29
Copyright 2003 by NYK LINE All rights reserved7
Table 1-3: NYK Standard Values for System Oil Management
for Two-Stroke Cycle Slow-Speed Engines (Crosshead Type)
Standard Values
MAN B&W
(MES)(HITACHI)
(KAWASAKI)
Wartsila RTA
(DU)
(MHI)
UEC
(MHI)
(AKASAKA)
(Others)
Max. 140 145 1351) Kinematic
viscosity Min.
cS
@40 15% 15% 10%
2) Flash point (PM) > 180
3) Water % v/v < 0.3
4) Total acid number increase mgKOH/g < 1.0
Max. (increase) 15 25 205) TBN
Min.
mgKOH/g
@KCIO4 3.06) Insolubles in Pentane (Method A) % m/m < 0.5
7) Insolubles in Toluene % m/m < 0.5
8) Ferrography < 50 + Trend
9) Metals
Fe, Cu, Sn, Pb, Ni, Cr)mg/kg < 20mg/kg + Trend
-
7/26/2019 Guidance for Lubricating Oil Management
10/29
Copyright 2003 by NYK LINE All rights reserved 8
Table 1-4: Engine Manufacture/Oil Company Standard Values for System Oil Management
for Two-Stroke Cycle Slow-Speed Engines (Crosshead Type)
Oil company Engine manufacture
Exxon Mobil
JOMO COSMONIP PON
OILW.artsila
Sulzer
MAN
B&Wothers
BP
CASTROLSHELL
MES
HITACHI
(MAN B&W)
Limits
W.artsila
DU
RTA
Limits
MHI
(UERTA)
Guide lines
CIMAC
Guide lines
Max.+25%
1)
+35%2)
128.8 136
1501)
1602)
1451)
1502)
1361)
1432)
+3.00 [135]1)
+3.50 [142]2)
+25 1)
+50 2)
+40% 160 +30%
+3.00 [135]1)
+3.50 [142]2)
Kinematic viscosity
(cSt @40)Min.
-5%1)
-15%2)
95.0 81.75
871)
832)
-2.95 [69]1)
-3.45 [65]2)
-25 1)
-50 2)
-15% -10%
-2.95 [69]1)
-3.45 [65]2)
Flash Point () Min. 180 160 200 160 180 190 (COC) 180 (COC) 180 (PM)
Water (%v/v) Max. 0.2 0.3 0.2 (0.3) 0.1 (0.2) 1.0 0.2 0.5(m/m) 0.2 0.20.491)
0.5
2)
Total acid number (mgKOH/g) Max . - 0> 11
1)
< 42)
+151)
Max. 30
121)
151)
16 (7)1)
30 (12)2)
+100% 30
TBN
(mgKOH/g)
Min. 3.1 53
1)
22)
31)
2 (2)1)
1 (1)2)
-30% 2
32)
Insolubles in Pentane
(% m/m)1.0 1.5 0.75 (1.0) 2.0 1.0
0.5 1.491)
1.52)
Insolubles in Benzene (% m/m)
Max.
1.0
2.0
Viscosity adjusting oil
Remarks
* Upper
limit of
Insolubles
in Pentane
is 1.5%
* Figure in ( ) shows the upperlimit of water content
* Figure in ( ) shows the
upper limit of insolubles(based on DIN)
* There are standard valuesfor metal content,
Ferrography, and FT-IR.
* Mobil DTE Oil HeavyMedium is used as a low
viscosity dilution oil.
* Viscosity
@100
* Viscosity in [ ]
shows @40
SAE30,
VI=105
* TBN values in( ) areapplicable to
all but threetypes of
engines ( RTA,MC, and
ME).
*Insoluble is
analyzed byShell Method.
* For a short
per iod of
time, water
content up
to 0.5% is
acceptable.
*Upper limit
of
Insolubles
in Toluene
is 0.6%.
*Upper limit
of
Ash is
2.0%.
* Viscosity @100(SAE 30)
* Water and Insolubles in
Pentane in ( ) showupper limits.
* Max. content ofmetals are 30 mg/Kg
* Upper limit of TBNshows increase value
against new oil
( ) shows Max or Min
Renewal year of data 2002.4 2002.4 2002.4 2002.4 2002.4 2002.4 2002.4 2002.4 2002.4 1997
1) Precautionary limit2) Mandatory limit
8
-
7/26/2019 Guidance for Lubricating Oil Management
11/29
Copyright 2003 by NYK LINE All rights reserved9
5. Items to be checked for system oil management
The following items are to be checked for system oil management.
5.1 Density
1) Ingress of drip oil usually increases the density of the system oil.2) Density is an important factor when selecting a gravity disc for the purifier.
3) Check the density of the system oil in use accordingly and confirm that a correct size of gravity
disc corresponding to the density of the system oil is used.
4) Density does not directly affect engine performance.
5.2 Kinematic Viscosity
1) Kinematic viscosity is an indication of fouling in the system oil and is a fundamental item
needed for system oil management.
2) Kinematic viscosity increases due to ingress of high viscosity oil, such as drip oil / HFO (Heavy
Fuel Oil) and an increase of insolubles in the system oil. The amount of drip oil largely
depends on the type of engine, the design of the stuffing box, and wear conditions. On RTA
type engines, for example, the amount of drip oil is large on C types, while the amount of drip
oil is relatively small on T types. On MAN B&W engines and MHI UEC engines the amount of
drip oil is moderate, between those of RTA type engines.
3) Ingress of low viscosity oil, such as MDO (Marine Diesel Oil) causes a decrease in viscosity of
the system oil.
4) When an unexpected increase or decrease in viscosity takes place, inspect for a cause of this
change and take necessary measures.
5.3 Flash Point
1) In many cases contamination with fuel oil is the main cause of a decrease in flash point.
However, there is almost no case history of a decrease in flash point for a low-speed engine.
2) On older types of MAN B&W engines where the oil system lines for the camshaft and the
system oil are different, the flash point of the camshaft oil may decrease due to contamination
of the fuel oil.
3) When a slight decrease in the flash point is observed, draw out some oil and supply new oil to
maintain a proper flash point.
4) When a remarkable decrease in flash point is observed, replace all of the system oil.
5) When an unexpected decrease in flash point takes place, inspect for a cause of the decrease and
take necessary measures.
5.4 Water Content
1) When water mixes into the system oil, the lubricity decreases, the additive deposits, and
-
7/26/2019 Guidance for Lubricating Oil Management
12/29
Copyright 2003 by NYK LINE All rights reserved10
corrosion takes place on the parts, in particular, lubricating parts are adversely affected.
2) Major causes of increases in water content for low-speed engines are malfunction of the purifier
or ingress of cooling water.
Ingress of water from the purifier is mainly attributed to improper selection of gravity disc.
Since fouling usually causes an increase in density of the system oil, check the density of thesystem oil in use accordingly and confirm that a proper size of gravity disc corresponding to
density of the system oil is used.
3) When a large quantity of water (0.5% or more) is contaminated, in principle, replace
all of the system oil with new oil.
4) Contaminated oil containing a large quantity of water is to be transferred to the settling tank
and the water content is to be removed through the following procedures:
a. After raising the heating temperature in the settling tank up to 80 to 85 , stop heating and
leave it for one day to allow the oil to settle and separate in the tank, extending the settling
time to ensure sufficient separation of water, and draining off water at the bottom of tank.
b. Conduct purification by circulating through the purifier and check water content with an
onboard water content meter.
c. When fresh water contamination is found, water removal can be performed by evaporation by
increasing the heating temperature up to 105 to 110 in the settling tank. In this situation,
bubbling with clean air is an effective remedy. However, do not exceed the heating
temperature of 98 when purification by circulating through the purifier is performed at the
same time.
d. In the event of seawater contamination, set the heating temperature lower than the temperature
of the oil flow through the purifier, and discharge as much water as possible through the purifier.
Sodium chloride may remain in system oil if the heating temperature is raised to an excessive
level in the settling tank.
e. After removing water content, request shore laboratory analysis and determine how best to deal
with the treated oil based on the analysis results.
5.5 TBN (Total Base Number)
1) TBN increases because of the influence of remaining additives in drip oil.
2) The degree of increase depends on the type of engine and the design of the stuffing box.
Although TBN in drip oil is 40 to 60mgKOH/g, these values vary with the type of engine and
the lubricating oil feed rate. TBN in system oil (new oil) is approximately 5mgKOH/g
3) When the value of TBN exceeds the standard value ranges, draw out some oil and supply new
oil to maintain the proper range.
-
7/26/2019 Guidance for Lubricating Oil Management
13/29
Copyright 2003 by NYK LINE All rights reserved11
5.6 TAN (Total Acid Number)
1) TAN increases due to external factors, such as sulfur compounds and additive remaining in drip
oil.
2) Usually TBN is used as a guide for system oil management. System oil is rarely affected by acid
materials and/or oxidation except on rare occasions when combustion gas in the scavenge spaceleaks into the crankcase.
5.7 Insolubles
1) Insolubles increase due to remaining additives which have deteriorated and combustion residues
contained in drip oil.
2) Insolubles have a significant effect on the wear on the bearing and scale adherence on the
heating transfer surface.
3) Insoluble includes toluene insolubles that identify oil-insoluble material in system oil and
pentane insolubles that identify solid and oxidation byproduct, such as resins. Usually pentane
insolubles are used for assessing characteristics of the system oil.
5.8 Metal
1) An ingress of wear particles resulting from abnormal wear on the bearing increases metal
content in the system oil.
2) Metal content is an important item for assessing engine condition.
3) An increase in metal content is a clear sign that engine condition may be worsening. By
assessing changes in metal content (quantity and kind), serious engine trouble can be avoided
before developing into cr itical conditions.
4) If metal content exceeds the standard range or if a rapid increase in a certain metal content is
being shown, it could indicate an abnormal increase in the amount of wear on the bear ings , and
an immediate investigation is to be carried out on the bearings and the loosened bolts. (check
for loosened bolts)
5.9 Ferrography
1) Ferrography is an analytical method that quantifies the levels of contaminant metal particles
present in system oil.
2) This is an important item for assessing engine conditions as well as metal composition.
-
7/26/2019 Guidance for Lubricating Oil Management
14/29
Copyright 2003 by NYK LINE All rights reserved12
Chapter 2: System Oil Management for Medium-Speed Engines
1. Characteristics of system oil for medium-speed engines
A four-stroke cycle medium-speed engine (trunk-piston type) has a structure in which the
system oil directly make contact with the combustion chamber and the combustion gas. Acharacteristic of system oil for medium-speed engines is that fouling and deterioration continue as a
result of the direct contact of combustion gas and the ingress of combustion residues, such as carbon.
On medium-speed engines heavier degradation of system oil takes place compared with
low-speed engines. In particular, the characteristic of system oil is greatly affected by combustion
conditions.
Improper system oil management may lead to serious accidents, such as burnt bearings, cracks
in the crankshaft, and fractures of the connecting rod.
The design of the engine has also a significant effect on the causes of failure in the bearing. On
a crankcase and the cylinder block with low rigidity, vibration causes unstable bearing clearances,
resulting in abnormal wear. Therefore, it is important to assess the characteristics of the engine.
The main point of system oil management for medium-speed engines is to take measures to
prevent fouling by combust ion gas and combust ion compounds. More specifically, system oil
management is to be carried out by placing emphasis on control of insolubles. System oil
degradation is mainly caused by the ingress of combustion residues (such as carbon) even under
normal conditions, however, lubricating oil itself also degrades as a result of combustion gas and
acid materials.
2. Balance of system oil circulation
A balance of system oil for medium-speed engines is almost same as illustrated in Figure 1-1.
The squares with a solid line in Figure 1-1 indicate lubricating oils replenished or mixed
into the circulating system, while the squares with a dotted line indicate lubricating oils
leaked or drawn out from the circulating system. Cylinder oil which has the same characteristics of
the system oil is occasionally supplied to the cylinder liner.
2.1 Lubricating oil for replenishment
(1) New Oil Replenishment
1) New oil is replenished at periodic intervals.
2) Ensure that enough new system oil, desirably the entire amount of system oil being circulated
that can be replaced at least once, is kept at all times in order to deal with any unexpected
accidents during which an entire amount of system oil would need to be replaced.
(2) Used Cylinder Oil
1) When cylinder oil is being fed, used cylinder oil containing combustion composition enters the
-
7/26/2019 Guidance for Lubricating Oil Management
15/29
Copyright 2003 by NYK LINE All rights reserved13
system oil.
2) When the amount of cylinder feed oil is large and the amount of new oil supplied to the
crankcase is small, insoluble content will increase. In such cases, draw out some system oil in
use.
2.2 Lubricating oil for consumption
(1) Scraping off by piston rings
1) The amount of cylinder oil scraped off by the rings is greatly affected by the combustion
condition.
2) In cases where severe vibration combustion is taking place, the amount of system oil
consumption may increase more than twice as much as the normal amount.
3) When the amount of system oil consumption is remarkably large, an engine load adjustment
is to be considered.
(2) Drawn out system oil
1) When constant deterioration of the system oil is observed, conduct drawing out
operations at periodic intervals.
2) Temporary drawing out is an effective remedy for sudden deterioration in properties of the
system oil.
(3) Leaked-off oil from purifier
1) This is the lubrication oil drained out from the purifier at cleaning.
(4) Other leaked-off oil
1) This is the lubrication oil leaked from the flanges on the piping.
3. Onboard system oil management
3.1 Maintaining a proper amount of system oil
1) Carry out replenishment or drawing out in a timely manner to maintain a proper amount of
system oil at all times.
2) Consumption of system oil greatly varies with combustion conditions. Special attention should
be paid to changes in the amount of system oi l consumption.
3) System oil tends to be affected by fouling with a decrease in the total amount of the system oil.
4) In general the amount of system oil for medium-speed engines is approximately 10 to 14m3 /
10000kw (7 to 10m3 / 10000PS)
5) Attention should also be paid to the amount of new oil.
-
7/26/2019 Guidance for Lubricating Oil Management
16/29
Copyright 2003 by NYK LINE All rights reserved14
3.2 Maintaining properties of system oil
3.2.1 Replenishment and Drawing out
1) Properties of system oil are affected to varying degrees by combustion condition.
2) Carry out replenishment with new oil in a timely manner to keep the property values of the oil
within the recommended standard values.3) When the amount of system oil is large or when the amount of system oil consumption is small,
draw out some oil and then replenish with new oil. On medium-speed engines fouling
progresses at all times. Therefore, when the amount of system oil consumption is small,
heavier fouling will take place. Special attention should be paid to changes in properties for
system oil management.
4) Except in an emergency, when the values of insolubles can be maintained within the standard
values, other properties can also be maintained.
5) Determine the optimum amount of replenishment or drawing out based on the results of
periodic analysis.
3.2.2 Treatment by purifier
(1) Carry out system oil treatment with the purifier.
1) Bypass purifying
a. Set the oil flow rate for the purifier at approximately 1700 lit/h /10000kw
(1300 lit/h/10000PS).
b. Set the oil flow temperature to between 80 and 85.
c. For a total blow type purifier, set the cleaning interval to two hours or less because calcium
compound, a main ingredient in additive, is liable to become hard if two hours is exceeded.
(2) Entire quantity purifying
Treat all of the system oil during a docking period when the main engine is stopped for a
prolonged period of time.
a. Transfer all of the system oil to the lubricating oil settling tank and purify it by circulating it
through the purifier. In addition, clean the lube oil sump tank.
b. Set the heating temperature in the tank to approximately 80 .
c. The oil flow volume through the purifier is to be adjusted to between two and three times the
entire amount of system oil (With 10m3 of system oil, for example, the oil flow volume
would be between 830 to 1250 lit/h).
3.4 System oil analysis
1) Request shore laboratories to make analysis at regular intervals.
2) When conducting shipboard analysis, check the accuracy of shipboard analysis results by
comparing the results with shore analysis.
-
7/26/2019 Guidance for Lubricating Oil Management
17/29
Copyright 2003 by NYK LINE All rights reserved15
3.4.1 Purposes of system oil analysis
1) To determine whether the system oil is usable or not
2) To assess the current condition of the engine (for example, detection of abnormal wear on
bear ings)
3) To review whether the management method for system oil is appropriate or not
3.4.2 Analysis interval
1) When no problem is observed: every three months
2) When a problem occurs: when the system oil condition corresponds to one or more of the
following cases/symptoms, carry out oil analysis every two weeks and assess the effect on the
abnormality.
When analysis results (A method) of pentane insoluble content exceeds 1.0% or more.
When metal content (Cu, Sn, Al, Fe, etc.) shows a tendency to increase compared to previous
analysis results despite the fact that new oil has been replenished.
When vanadium and nickel, which are metal elements in fuel oil, show a tendency to increase,
and at the same time, a decrease in the flash point or an increase in insoluble content are
observed.
When frequent clogging takes place in the secondary and tertiary strainer installed on the
lubricating oil pipe.
When the chief engineer concludes that there is an abnormality in system oil management.
Abnormalities include the following situations:
*Analysis results show that the values of properties are out of the usable limit.
*Onboard spot test indicates that there is an abnormality in the system oil in use.
* Abnormal increase in lubricating oil consumption is observed.
3.4.3 Sampling
1) Samples (the oil actually circulating through the system) are to be taken from the sampling cock
or the air vent valves on the cooler, the pump, and the filter.
2) Prepare a clean container for sampling.
3) Sampling is to be conducted after the drain is thoroughly discharged.
4) Usually the amount of sample is 0.5 to 1 liter. (It depends on the requirements of the shore
laboratories.)
5) During trouble, samples are to be taken at the inlet/outlet of the damaged components (Usually
at the outlet of the lubricating oil pump). When a sample is taken at the outlet of the filter, wear
particles have been captured on the filer; cons equently, the cause of the problem may not be
identified.
-
7/26/2019 Guidance for Lubricating Oil Management
18/29
Copyright 2003 by NYK LINE All rights reserved16
4. Standard Values for Lubricating Oil Management
On medium-speed engines, fouling is heavier than that of low-speed engines and the fouling
may develop very rapidly depending on combustion conditions. In addition, the fouling status varies
greatly with the type of engine. Therefore, it is important to assess the characteristic of the engine
and conduct system oil management with time allowance to some degree.
4.1 Standard Values for System Oil Management
(four-stroke cycle medium-speed engines (trunk-piston type))
The NYK standard values for system oil management for four-stroke cycle medium-speed
engines (trunk-piston type) are shown in Table 2-1.
Table 2-1: NYK Standard Values for System Oil Management
for Four-Stroke Cycle medium-Speed Engine (Trunk-piston Type)
Standard Values
1) Kinematic Viscosity SEA 30SEA 40 % 25 %
2) Flash Point (PM) > 170
3) Water % v/v < 0.3
4) Total acid number (increase) mgKOH/g < 1.0
5) TBNmgKOH/g
(@KCIO4)> 16
6) Insolubles in Pentane (Method A) % m/m < 1.5
7) Insolubles in Toluene % m/m < 1.0
8) Ferrography < 50 + Trend
9) Metals Fe, Cu, Sn, Pb, Ni, Cr) mg/kg < 20mg/kg + Trend
5. Items to be checked for system oil management
The following items are to be checked for system oil management.
5.1 Density
1) Ingress of insolubles (combustion composition) usually increases the density of the system oil.
2) Density is an important factor when selecting a gravity disc for the purifier.
3) Check the density of the system oil in use accordingly and confirm that a correct size of gravity
disc corresponding to density of the system oil is used.
4) Density does not directly affect engine performance.
5.2 Kinematic Viscosity
1) Kinematic viscosity is an indication of fouling in the system oil and is a fundamental item
needed for system oil management.
2) Kinematic viscosity increases due to ingress of high viscosity oil, such as HFO (Heavy Fuel
Oil) and an increase of insoluble content in the system oil.
-
7/26/2019 Guidance for Lubricating Oil Management
19/29
Copyright 2003 by NYK LINE All rights reserved17
3) Ingress of low viscosity oil, such as MDO (Marine Diesel Oil), causes a decrease in viscosity of
the system oil.
4) When an unexpected increase or decrease in viscosity takes place, inspect for a cause of this
change and take necessary measures.
5.3 Flash Point
1) In many cases contamination with fuel oil is the main cause of a decrease in flash point.
2) When a slight decrease in flash point is observed, draw out some oil and supply new oil to
maintain a proper flash point.
3) When a remarkable decrease in flash point is observed (170 or less), replace all of the system oil.
4) When an unexpected decrease in flash point takes place, inspect for a cause of the decrease and
take necessary measures.
5.4 Water Content
1) When water mixes into the system oil, the lubricity decreases, the additive deposits, and
corrosion takes place on the parts, in particular, lubricating parts are adversely affected.
2) Major causes of increases in water content for medium-speed engines are malfunction of the
purifier or ingress of cooling water. Ingress of water from the purifier is mainly attr ibuted to
improper selection of gravity disc. Since fouling usually causes an increase in density of the
system oil, check the density of the system oil in use accordingly and confirm that a proper size
of gravity disc corresponding to density of the system oil is used.
3) When a large quantity of water (0.5% or more) is contaminated, replace all of the system oil
with new oil.
4) Contaminated oil containing a large quantity of water is to be transferred to the settling tank
and the water content is to be removed through the following procedures:
a. After raising the heating temperature in the settling tank up to 80 to 85 , stop heating and
leave it for one day to allow the oil to settle and separate in the tank, extending the settling
time to ensure sufficient separation of water, and draining off water at the bottom of the tank.
b. Conduct pur ification by circulating through the pur ifier and check water cont ent with an
onboard water content meter.
c. When fresh water contamination is found, water removal can be performed by evaporation by
increasing the heating temperature up to 105 to 110 in the settling tank. In this situation,
bubbling with clean air is an effective remedy. However, do not exceed the heating
temperature of 98 when purification by circulating through the purifier is performed at the
same time.
d. In the event of seawater contamination, set the heating temperature lower than the
temperature of the oil flow through the purifier, and discharge as much water as possible in
the purifier. Sodium chloride may remain in the system oil if the heating temperature is raised
-
7/26/2019 Guidance for Lubricating Oil Management
20/29
Copyright 2003 by NYK LINE All rights reserved18
to an excessive level in the settling tank.
e. After removing water content, request shore laboratory analysis and determine how best to
deal with the treated oil based on the analysis results.
5 .5 TBN (Total Base Number)1) TBN decreases as a result of ingress of combustion gas and mixture of acid substance contained
in combustion composition.
2) The degree of decrease is affected by combustion conditions and sulfur content in fuel oil.
5.6 TAN (Total Acid Number)
1) TAN increases as a result of external factors, such as sulfur compounds and additive remaining
in drip oil.
2) Usually TBN is used as a guide for system oil management.
5.7 Insolubles
1) Insolubles have a significant effect on the wear on the bearings.
2) Insoluble content is a fundamental item needed for system oil management for medium-speed
engines.
3) Insolubles include toluene insolubles that identify oil-insoluble materials in system oil and
pentane insolubles that identify solid and oxidation byproducts, such as resins. Usually, pentane
insolubles are used for assessing characteristics of the system oil
5.8 Metal
1) An ingress of wear particles resulting from abnormal wear on the bearings increases metal
content in the system oil.
2) Metal content is an important item for assessing engine condition.
3) An increase in metal content is a clear sign that engine condition may be worsening. By
assessing changes in metal content (quantity and kind) serious engine trouble can be avoided
before developing into cr itical condition.
4) If metal content exceeds the standard range or if a rapid increase in a certain metal content is
being shown, it could indicate an abnormal increase in the amount of wear on the bear ings , and
an immediate investigation should be carried out on the bearings and the bolts. (check for
loosened bolts)
5.9 Ferrography
1) Ferrography is an analytical method that quantifies the levels of contaminant metal particles
present in system oil.
2) This is an important item for assessing engine conditions as well as metal content composition.
-
7/26/2019 Guidance for Lubricating Oil Management
21/29
Copyright 2003 by NYK LINE All rights reserved19
Chapter3: Economical System Oil Management for Slow-Speed Engines
1. Replenishment method for system oil
Based on the NYK Standard for system oil management and the SMS Manual, onboard system
oil management has been implemented in accordance with the actual situation on each vessel. Theresults of the reviews conducted so far suggest that there is still some margin to reduce new oil
consumption of system oil.
The amount of new oil consumption can be reduced by adopting the most suitable method from
the following three methods, with some consideration given to the characteristics of engine as well
as the properties of system oil in use.
1) Replenishment with only new oil
2) Re-use of stuffing box leaked oil as replenishment oil (recycling oil)
3) Use of low viscosity oil as replenishment oil
Figure 3.1 shows replenishment methods and guides for property values of the system oil.
2. Replenishment with only new oil
2.1 Guide for implementation
This method is applicable to the engines in which the properties of system oil can be maintained
within the following ranges when replenishing with only new oil.
1) Kinematic Viscosity: 130 to 135 cSt
(note that the value must not exceed the upper limit of the standard value)
2) TBN increase : 15 to 20 mgKOH/g
(note that the value must not exceed the upper limit of the standard value)
3. Re-use of stuffing box leaked oil
1) This is a method in which stuffing leaked oil is collected and used together with new oil after
purifying it with the pur ifier. Stuffing leaked oil has similar properties to system oil.
2) For implementing this method, another settling tank for storage of re-use oil (recycling oil) is
necessary in addition to a storage tank for new oil.
New Oil Upper limits
Kinematic 95~105 130~135 135~145viscosity(cSt @40)
TBN 5~ 7 15~20 20~25(mgKOH/g)
Replenishment
with only new oil
Re-use of stuffing
Box leak oil
Use of Low
Viscosity Oil
Fig. 3.1: Guides for Selection of Replenishment Method
(Convergence Values When Supplied Only New Oil)
-
7/26/2019 Guidance for Lubricating Oil Management
22/29
Copyright 2003 by NYK LINE All rights reserved20
3) This method is not applicable to the engines in which the same drain line is used for the stuffing
box leaked oil and the lantern drain oil.
3.1 Guide for implementation
This method is applicable to the engines in which the properties of system oil can be maintainedwithin the following ranges when replenishing with only new oil.
1) Kinematic Viscosity: 135 to 130 cSt or less
2) TBN increase : 20 to 15 mgKOH/g or less
3.2 Procedures for recycling
The following procedures are to be taken for re-use of stuffing box leaked oil:
3.2.1 Collecting stuffing box leaked oil
1) Transfer stuffing box leaked oil to the settling tank.
3.2.2 Heating/Settling/Draining
1) After raising the heating temperature in the settling tank up to 80 to 85 , leave it for
approximately one day and drain off sediment.
2) When a large quantity of impurities is found in the oil, stop heating the oil during the settling
period to improve sedimentation.
3) When water content (fresh water) is large, the heating temperature may be increased up to
105 to evaporate contained water. In this situation, bubbling with clean air is an effective
remedy.
3.2.3 Purifying (Refer to Figure 3-2)
1) Set the heating temperature in the settling tank between 80 to 85 and conduct purification
by circulating through the purifier for at least one day.
2) Adjust the flow rate in the purifier at 30% or less of the rated volume flow rate and set the
heating temperature of the oil through the purifier between 85 to 90 .
3) As heavy fouling will most likely take place in the purifier, shorten overhauling/ maintenance
intervals in accordance with fouling status.
4) If two settling tanks are available, more effective purification results can be obtained by
purifying the entire quantity of oil between the tanks via the purifier.
Collecting stuffing
box leaked oil
Heating
Settling
Draining off
Purifying
Analyzing
PropertiesDetermining
blending rati o
Replenishment
-
7/26/2019 Guidance for Lubricating Oil Management
23/29
Copyright 2003 by NYK LINE All rights reserved21
3.2.4 Analyzing Properties/determining blending ratio
1) Request shore laboratories to make analysis of properties of the recycling oil.
Determine whether the recycling oil is usable or not. Determine a blending ratio with new oil.
2) Determine a blending ratio in accordance with the actual condition of the system oil on each
vessel because the type of engine and maintenance conditions affect the blending ratio.
3.2.5 Replenishment
1) Do not carry out replenishment with only recycled oil to avoid a large decrease in properties ofthe system oil. New oil must be used together with recycled oil.
4. Use of Low Viscosity Oil
1) This method is applicable to engines on which a rapid increase is observed in kinematic
viscosity and TBN, resulting from a large amount of used lubricating oil mixture; consequently,
frequent drawing out operations should be carried out.
2) For implementing this method, another settling tank for storage of low viscosity oil is necessary
in addition to a storage tank for new oil.
4.1 Guide for implementation
This method is applicable to engines in which the properties of system oil can be maintained
within the following ranges when replenishing with only new oil.
1) Kinematic Viscosity: 135 to 145 cSt or more
2) TBN increase : 20 to 25 mgKOH/g or more
4.2 Use of Low Viscosity Oil
Separated from the storage tank for normal system oil, low viscosity oil should be stored in
Circulating purification with one tank Entire quantity purification with two tanks
Fig. 3-2: Purification for re-use oil
Collect tank
for stuffing
box leaked oil
Storage
tank
for new oil
Settling
tank for
re-use oil
Purifier Main engine
Purifier
Collect tank
for stuffing
box leaked oil
Settling
Tank
No.1
Storage
tank for
new oil
Main engine
Settling
tank
No.2
Purifier
Purifier
B ass Purif in
-
7/26/2019 Guidance for Lubricating Oil Management
24/29
Copyright 2003 by NYK LINE All rights reserved22
only the storage tank provided for low viscosity oil and used
together with new oil as replenishment oil. Since the
blending rat io is greatly affected by the type of engine,
maintenance conditions, the degree of increase in kinematic
viscosity and the properties of the low viscosity oil,determine a blending ratio in accordance with the actual
condition of the system oil on each vessel.
Table 3-1 shows the properties of low viscosity oil
produced by the major oil companies.
Table 3-1: Low Viscosity Oils of Major Oil Companies
Oil company Name of oil DensityKinematic
viscosity 40/100TBN
NIPPON OIL Marine S20 0.884 71.4 / 9.03 7
JOMO ATLANTA MARINE D 2005 0.878 44.8 / 6.76 5
COSMO COSMO MARINE 2005 0.880 49.13 / 7.17 5.5
SHELLMelina S Oil 20
Merina Oil 20
0.882
0.893
67.0 / 8.7
67.9 / 8.8
5
8
EXXON MOBIL Mobil DTE Oil Heavy Medium 0.875 64 /8.6
BP CASTROL CASTROL CDX 20 0.890 65 / 8.3 5
5. Replenishment ratio of recycling oil and low viscosity oil
Figure 3-4 shows a simplified flow diagram
for system oil in the circulating system. In the
circulating system the amount of oil supplied
into the circulating system (oil-in) makes up for
the amount of oil leaked out or drawn out of the
circulating system (oil-out). Thus, the total
amount of system oil is controlled to maintain a
certain level. For an engine in which the amount
of oil-out is large, replenishment with only new
oil will result in an increase in the amount of
oil-in. As a result, the standard value specified
for the system oil management becomes lower.
Meanwhile, for an engine in which the
amount of oil-out is small, the standard value
specified for the system oil management tends to
be higher because the amount of oil-in will
decrease. The amount of oil-in and oil-out is greatly affected by the design of the stuffing box and
the wear condition of the seal rings. When the system oil leaks, a large amount of system oil will
Storage tank
for new oil
Main engine
Storage tank
for low
viscosit oil
Purifier
Bypass Purifying
Fig. 3-3: Use of Low Viscosity Oil
Other
leaked oil
Sump tank
of engine
Cylinder
oil
Purifier
Either is used
Drippedoil
Leaked oil
of stuff. box
Collect tank
of leaked oil
Drawing
New oil
tank
(Normal oil)
Low
Viscosityoil tank
Re-use
oil tank
Fig. 3-4: Flow diagram of system oil
-
7/26/2019 Guidance for Lubricating Oil Management
25/29
Copyright 2003 by NYK LINE All rights reserved23
drain out into the system. When the used cylinder oil passes the stuffing box seal rings, a large
amount of oil contaminated will drain into the crankcase.
In this section, we consider the use of recycled oil (leaked oil from the stuffing box) and proper
system oil management corresponding to the amount of drip oil.
5.1 Reuse of recycled oil (stuffing box leak oil)
Calculated values of kinematic viscosity with use of recycled oil are shown in Table 3-2.
Figures 3-5, 3-6, and 3-7 show the predicted transition of kinematic viscosity and TBN as a
function of the time when recycled oils of different blending ratios are used. Table 3-2 reports that
the calculated values of kinematic viscosity with use of recycled oil at different blending ratios are
compared to the value of kinematic viscosity with only new oil when the total amount of supply oil
(new oil + recycled oil) is maintained at the same level.
When the upper limit value of kimematic viscosity is specified at approximately 140cSt, a
reduction of new oil replenishment can be expected in an engine in which kinematic viscosity is
controlled at 130cSt or less. In particular, in an engine in which kinematic viscosity is controlled at
115cSt or less, 50% or greater reduction effectiveness can be expected.
Table 3-2: Calculated Values of Kinematic Viscosity and TBN with Use of Re-Use Oil
Percentage of
re-use oil ()
= Reduction of new oilConverged values Kinematic viscosity / TBN
0 (New oil only) 110.0 / 5.1 115.0 / 7.4 120.0 / 9.6 125.0 / 11.7 130.0 /13.7
20 114.6 / 7.3 120.6 / 10.3 123.9 / 11.8 132.2 / 15.6 137.9 / 18.0
30 117.9 / 8.4 124.9 / 11.7 128.0 / 13.3 137.1 / 17.3 143.1 / 19.8
40 122.1 / 9.9 129.5 / 13.4 133.4 / 15.2 143.3 / 19.4 149.7 / 21.9
50 128.0 / 11.8 136.3 / 15.7 140.7 / 17.5 151.3 / 21.9 153.5 / 22.7
55 131.9 / 13.0 140.7 / 17.0 148.8 / 20.4
60 136.5 / 14.5 146.0 / 18.7 154.5 / 22.1
65 142.6 / 16.3 152.6 / 20.6
70 150.4 / 18.5
Note: 1) Recycled oil kimematic viscosity: 110% of the system oil in use
TBN : 2mgKOH/g larger than the system oil in use2) Recycled oil ratio is the rate of the total amount of supply.
Figures 3-5, 3-6 and 3-7 show prediction curves in which the values for kinematic viscosity of
the system oils converge at 110, 120, 125cSt respectively when only new oil with 100 cSt at 40 is
supplied. In all cases, kimematic viscosity of the recycled oil is 110% and TBN is +2mgKOH/g of
the system oil in use. For example, when kimematic viscosity of the system oil converges at 110cSt
on an engine whose system oil is controlled by only new oil, kimematic viscosity will converge at
128cSt and TBN will converge at +11.8 mgKOH/g respectively by using recycled oil with 50% of thetotal amount of supply oil.
-
7/26/2019 Guidance for Lubricating Oil Management
26/29
Copyright 2003 by NYK LINE All rights reserved24
100
110
120
130
140
150
0 20000 40000 60000
0
0.4
0.5
0.6
0.650
5
10
15
20
25
0 20000 40000 60000
(c
St@40)
TBN(mg
KOH/g)
(hr) (hr)
Ratio of
Re-use oil
Fig. 3-5: Prediction Curves in Kinematic Viscosity and TBN at Different
Blending Ratio of Recycled Oil (Convergence Value for New Oil:110cSt)
Running hours (hr) Running hours (hr)
TBN(mgKOH/g)
Viscosity(cSt@40)
100
110
120
130
140
150
0 20000 40000 60000
0
0.2
0.3
0.4
0.5
0
5
10
15
20
25
0 20000 40000 60000
(cSt@40)
TBN(mgKOH/g)
(hr) (hr)
Fig. 3-6: Prediction Curves in Kinematic Viscosity and TBN at Different
Blending Ratio of Recycled Oil (Convergence Value for New Oil:120cSt)
Ratio ofRe-use oil
Running hours (hr) Running hours (hr)
TBN(mgKOH/g)
Viscosity(cSt@40)
100
110
120
130
140
150
0 20000 40000 60000
0
0.2
0.3
0.4
0
5
10
15
20
25
0 20000 40000 60000
(cSt@40)
TBN(mgKOH/g)
(hr) (hr)
Fig. 3-7: Prediction Curves in Kinematic Viscosity and TBN at Different
Blending Ratio of Recycled Oil (Convergence Value for New Oil:125cSt)
Ratio ofRe-use oil
Running hours (hr) Running hours (hr)
TBN(mgKOH/g
)
Viscosity(cSt@40
)
-
7/26/2019 Guidance for Lubricating Oil Management
27/29
Copyright 2003 by NYK LINE All rights reserved25
5.2 Make up with low viscosity oil
Calculated values of kinematic viscosity and TBN of system oil with use of low viscosity oil are
shown in Table 3-3. Figures 3-8, 3-9 and 3-10 show the predicted transition of kinematic viscosity
and TBN as a function of the time when low viscosity oils at different blending ratios are used.
The amount of replenishment with which the target values of 135cSt and 140cSt can bemaintained are shown in Table 3-3. The values for LO consumption and TBN in Table 3-3 are
represented in accordance with four different blending ratios and viscosities of low viscosity oils.
(Values for the blending ratios are compared to replenishment with only new oil (100cSt), considered
to have a value of 100%.) The lower the kinematic viscosity of low viscosity oil and the greater the
blending rat io, the larger the effectiveness in reducing the amount of new oil to be supplied. However,
when TBN of both low viscosity oil and new oil have the same value, a reduction of TBN in blending
oil cannot be expected. In particular, when kinematic viscosity in low viscosity oil is low and the
blending rat io of low viscosity oil is large, special attention should be paid. On actual vessels the
relationship between kinematic viscosity of low viscosity oil and TBN does not necessarily
correspond to Table 3-3, however, when the target value of kinematic viscosity of the system oil is
set at 140cSt, the blending ratios need to be at 40% or less with low viscosity oil with 70cSt and 20%
or less with low viscosity oil with 50cSt.
Figure 3-8, 3-9 and 3-10 show the relationship between the blending ratios of low viscosity oil
(with 70cSt of kinematic viscosity) and the kinematic viscosity and TBN of the system oil when the
total amount of supply oil (new oil + low viscosity oil) is maintained at the same level. These
figures also illustrate prediction curves in which values of the kinematic viscosity of the system oils
converge at 145, 150, and 160 cSt respectively when only new oil with 100 cSt at 40 is supplied.
When the target value for kinematic viscosity of the system oil is set at 140cSt, the blending
ratios will be at 15% with 145cSt (convergence value for new oil), 30% with 150cSt, and 70% with
160cSt respectively. As the total amount of supply oil (new system oil + low viscosity oil) stays at
the same level, the value of TBN will also stay at the same level regardless of the blending ratio, and
TBN will converge at 21.5 mgKOH/g with 145cSt (convergence value for new oil), 23.5mgKOH/g
with 150cSt,and 27.0 mgKOH/g with 160cSt respectively.
-
7/26/2019 Guidance for Lubricating Oil Management
28/29
Copyright 2003 by NYK LINE All rights reserved26
Table 3-3: Calculated Values of Viscosity and TBN with Use of Low Viscosity Oil
Target viscosity:135cSt Target viscosity:140cStRatio of
low viscosity oil
ratio to thetotal amount
Viscosity of
low viscosity oil
(cSt)
LO
consumption
%
TBN
Convergence
value(mgKOH/g)
LO
consumption
TBN
Convergence
value(mgKOH/g)
50 66 + 22.3 68 + 24.0
60 73 + 21.1 75 + 22.9
70 80 + 20.0 81 + 21.920 %
100 100 + 17.4 100 + 19.3
50 49 + 26.0 52 + 27.5
60 57 + 24.0 60 + 25.7
70 66 + 22.3 69 + 24.040 %
100 100 + 17.4 100 + 19.3
50 44 + 27.4 46 + 28.9
60 52 + 25.3 55 + 26.870 61 + 23.3 64 + 24.9
50 %
100 100 + 17.4 100 + 19.3
50 39 + 28.7 42 + 30.1
60 47 + 26.5 50 + 27.9
70 57 + 24.2 59 + 25.860 %
100 100 + 17.4 100 + 19.3
TBN of low viscosity oil is assumed to be equal.
Drawing out of using oil is not taking into consideration.
-
7/26/2019 Guidance for Lubricating Oil Management
29/29
100
120
140
160
0 20000 40000 60000
0
0.5
0.6
0.7
0.9
0
5
10
15
20
25
30
0 20000 40000 60000
(cSt@
40)
TBN(mgKOH
/g)
(hr) (hr)
Fig. 3-10: Prediction Curves in Kinematic Viscosity and TBN at Different Blending
Ratio of Low Viscosity Oil (Convergence Value for Normal Oil:160cSt)
Ratio oflow vis.
oil
Running hours (hr) Running hours (hr)
TBN(mgKOH
/g)
Viscosity(cSt@
40)
100
120
140
160
0 20000 40000 60000
0
0.3
0.4
0.5
0.6
0
5
10
15
20
25
30
0 20000 40000 60000
(cSt@40)
TBN(mgKOH/g)
(hr) (hr)
Ratio oflow vis.
oil
Running hours (hr) Running hours (hr)
TBN(mgKOH/g)
Viscosity(cSt@40)
Fig. 3-9: Prediction Curves in Kinematic Viscosity and TBN at Different Blending
Ratio of Low Viscosity Oil (Convergence Value for Normal Oil:150cSt)
100
120
140
160
0 20000 40000 60000
0
0.15
0.3
0.450
5
10
15
20
25
30
0 20000 40000 60000
(c
St@40)
TBN(mg
KOH/g)
(hr) (hr)
Ratio of
low vis.oil
Running hours (hr) Running hours (hr)
TBN(mgKOH/g)
Viscosity(cSt@40)
Fig. 3-8: Prediction Curves in Kinematic Viscosity and TBN at Different Blending
Ratio of Low Viscosity Oil (Convergence Value for Normal Oil:145cSt)