Lubricating Oil Specification

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Requirement

This document is valid for the following engine types: L16/24, L21/31, L23/30H, L27/38, L28/32H, V28/ 32H, V28/32S

For the engines, a HD-lub. oil (heavy duty) corresponding to at least type CD Comercial Class D after API service system (meets MIL-L-2104 C and D) has to be used.

The oil should be rust and oxidation inhibited.

When selecting a lubricating oil, attention must be paid to the fuel oil sulphur content.

Due to generating running mode for HOLEBY's engines, where the lub. oil consumption depends on running time and the fuel oil consumption and following the sulphur input to the lub. oil depends on the load, a lower TBN-value (Total Base Number) than normal for main engines is needed.

Viscosity

30* 105 mm2/sec at 40° C L16/24, L21/31, L27/38

40 145 mm2/sec at 40° C

Stationary

L16/24, L21/31, L27/38

L23/30H, L+V28/32H, V28/32S

40145 mm2/sec at 40° C

*At cooling water temperatures above 32° C SAE 40 oil can be used. In this case, please contact MAN B&W, Holeby.

If load profile is different, this should be taken in consideration.

In the long run though, the operation results are the criteria that prove which TBN is the most economical one for efficient engine operation.

General

Guiding Values

Based on typical load profile for marine GenSet (5060% of rated power)

Based on typical load profile for stationary GenSets (50-100% of rated power)

Based on typical load profile for variable speed engine, pumps (10-100% of rated power)

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General

During operation of trunk engines the lubricating oil will be contaminated slowly by small particles originating from the combustion.

The burning of heavy fuels will normally increase this contamination due to the increased content of carbon residues and other impurities.

Contamination of lubricating oil with water, fresh or salt, can also take place.

A certain amount of contaminants can be kept suspended in the lub. oil without affecting the lubricating properties.

But the condition of the lub. oil should be kept under observation by analyzing oil samples. See also 504.04 "Criteria for Cleaning/Exchange of Lubricating Oil".

The engine bearings are protected by the full-flow lub. oil filter built onto the engine, the filter cartridges having a fineness of 15 micron and the safety filter a fineness of 60 micron.

The condition of the lub. oil can be maintained/ reestablished by exchanging the oil at fixed intervals or based on analysis results.

Cleaning with Centrifugal Separators

A more economical solution is to maintain the condition by continuous treatment. Experience has proved that centrifuging is superior to other methods of cleaning lubricating oils.

The optimum cleaning effect is achieved by keeping the lubricating oil in a state of low viscosity for a long period in the centrifuge bowl.

Low viscosity is obtained by preheating the lubricating oil to a temperature of 85 °C - 95 °C.

Slow passage of the lubricating oil through the centrifugal separator is obtained by using reduced flow rate and by operating the separator 24 hours a day, only stopping when cleaning of the bowl is necessary.

When treating detergent type lubricating oil, the flow rate is usually recommended to be reduced to 15-25%

of the rated flow of the separator.

In order to keep the amount of lubricating oil in the engine in good condition, it is necessary to treat 0.27 l/kw per hour (0.20 l/BHP per hour).

A centrifuge for treating this amount of lubricating oil under the mentioned derated flow conditions should have a rated capacity of 1.08-1.8 l/kw per hour (0.8- 1.3 l/BHP per hour), but in each case the separator manufacturer's recommendations for capacity and operation instructions should be followed.

For engines with cartridge-type oil filters (dept filters), continuous and efficient purification of the oil in the separator is essential to ensure long service life of the cartridge filters.

For cleaning of the lubricating oil system after overhauls and inspection of the lub. oil piping system, see section 515.

Deterioration of Oil

Oil seldom loses its ability to lubricate, i.e. to form a friction-decreasing oil film, but it may become corrosive to the steel journals of the bearings in such a way that the surface of these journals becomes too rough and wipes the bearing surface.

In that case not only the bearings must be renewed, but the journals must be polished. Corrosiveness of the lubricating oil is due to either far advanced oxidation of the oil itself (TAN) or to the presence of inorganic acids (SAN). In both cases the presence of water will multiply the effect, especially an influx of seawater as the chloride ions act as an inorganic acid.

Oxidation of Oils

At normal service temperature the rate of oxidation is insignificant, but the following factors will accelerate the process:

High Temperature

The temperature level will generally rise if the coolers

L23/30H

are ineffective.

High temperature will also arise in electrical preheaters if circulation is not continued for 5 minutes after the heating has been stopped, or if the heater is only partly filled with oil.

chamber.

In a grave case of oil deterioration, the system should be cleaned thoroughly and refilled with new oil.

Catalytic Action

Oxidation of the oil will be considerably accelerated if catalytic particles are present in the oil. Wear particles of copper are especially harmful, but also ferrous particles and rust are active. Furthermore, the lacquer and varnish-like oxidation products of the oil itself have an accelerating effect. Continuous cleaning of the oil is therefore important to keep the sludge content low.

Signs of Deterioration

If circulating oil of inferior quality is used and the oxidative influence becomes grave, prompt action is necessary as the last stages in the deterioration may develop surprisingly quickly, i.e. within one or two weeks. Even if this seldom happens, it is wise to be acquainted with the signs of deterioration. These may be some or all of the following:

-Sludge precipitation in purifier multiplies.

-Smell of oil becomes acrid or pungent.

-Machined surfaces in crankcase become coffee brown by a thin layer of lacquer.

-Paint in crankcase peels off or blisters.

-Excessive carbon is formed in the piston cooling

Water Washing

Water washing of HD-oils must not be carried out.

Water in the Oil

If the TAN is low, a minor increase in the fresh water content of the oil is not immediately detrimental while the engine is running. Naturally, it should be brought down again as quickly as possible (below 0,2% water content, which is permissible). If the engine is stopped when corrosion conditions are unsatisfactory, it should be turned just over 1/2 revolution once every hour (i.e. stop in different positions) while the oil circulation and purifying at a high preheating temperature continue to remove water. Water in the oil may be noted by steam formation on the sight glasses, by appearance, or ascertained by immersing a piece of glass or a soldering iron heated to 200-300°C in an oil sample. If there is a hissing sound, water is present. If a large quantity of water has entered the oil system, it may be profitable to suck up sedimented water from the bottom of the tank. Taste the water for salt. If salty, an oil sample should be analysed immediately for chloride ions.

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Description

Page 2 (2)

5.Neutralization Number

Limit value : 0.4-1.0 above typical level Unit : mgKOH/g

Possible test method : ASTMD-974

6.The Total Contamination (insolubles Content) Heptane insolubles.

Limit value : < 1.5 generally, depending upon actual dispersant value and the increase in viscosity.

Unit : Weight %

Possible test

method : ASTM D-893 procedure B in n- Heptane.

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Replacement of Lubricating Oil

It is not possible to predict the expected life time for lubricating oil, as it is not possible for the engine manufacturer to know which fuel and lubricating oil qualities will be used and under which operation conditions the engine will be operated.

A replacement of lubricating oil is required when the oil's identification values have changed no that the lubricating cleaning and neutralization properties no longer are sufficient.

Exchange of the lub. oil has to be based on the oil suppliers evaluation of samples of oil in service. Samples should be forwarded at appropriate intervals at least once every three months depending of running-mode and results of last analysis.

The oil sample should be taken after the filter and, if possible, while the engine is running as this will ensure that the test will be representative for the whole change in the engine.

Evaluation of the Lubricating Oil Condition

For evaluating the conditions of a used oil, the following guidance conditions are normally sufficient. Anyway, all parameters have to be evaluated as a whole, and no single can be taken as a criterion for changing oil.

1. Viscosity

2. Flash Point

Limit value : > 185° C

Possible test

method : Setaflash tests (cut of point cor relates with 204° C i ASTM D-92

(coc)

General

3. Water Content

4. Total Base Number (TBN-Number)

Due to the generating running mode for HOLEBY's engines, where the lub. oil consumption depends on running time and the fuel oil consumption and following the sulphur input to the lub. oil depends on the load, a lower TBN-value than normal for main engines is needed.

Following guiding values can be given:

The TBN is normally reduced gradually with the time of operation. The influential elements are the sulphur content in the fuel oil, the lubricating oil amount and the amount of re-filling due to normal consumption. After a certain time of ope-ration, the TBN will stabilize at a lower value, the TBN equilibrium.

General

Re-filling should be carried out with lubricating oil of the initial TBN.

5. Neutralization Number

6. The Total Contamination (insolubles Content) Heptane insolubles

Limit value : < 1.5 generally, depending upon actual dispersant value and the increase in viscosity.

Possible test

method : ASTM D-893 procedure B in n- Heptane.

Additionally

test : If the level in n-Heptane insolubles is considered high for the type of oil and application, the test could be followed by a supplementary determination in Toluene.

Also infra red test can be used.