Final 22.docx

Boiler Starting Failure – Troubleshooting

Failure in boiler starting is a common phenomenon on ship. There can be several reasons for the failure in staring of a boiler. In this article we will learn about the most common reasons for not starting of boiler. 1) Fuel inlet valve to the burner is in close position: The fuel line for boiler’s burner consists of several valves located at fuel tank, pumps suction, discharge valve, or valve before the boiler burner. Any of these can be in closed position resulting in starvation of fuel. 2) Line filter at the inlet of the fuel line for burner is choked: If the system runs in heavy oil then there are chances of filters in the line getting choke. To avoid this, boiler system are normally built for changeover from diesel to heavy oil during starting and heavy to diesel during stopping. This keeps the filter and the fuel line clean. 3) Boiler fuel supply pump is not running: There are two main reasons for fuel pump not running. Normally when the pumps are in pairs, the change over auto system is kept in manual position, and if the operating pump trips, the stand by pump will not start automatically. Another reason is tripping of pump due to short circuit in the system etc. Solenoid valve in the fuel supply line is malfunctioning Nowadays most of the system adopts advance automation, but their can be a possibility wherein the solenoid in the fuel supply line is malfunctioning and not opening. 5) Flame eye is malfunctioning: A Flame eye is a photocell operated flame sensor fitted directly on the refractory to detect weather the burner is firing or not. If the flame eye unit is malfunctioning, then it will give a trip signal even before the burner starts firing. 6) Air or Steam ratio setting is not proper

For proper and efficient combustion, air fuel ration is very important, if the supply of air is excess then there will be excess of smoke, and if it exceeds more than normal level the combustion will burn off causing flame failure.

7) Forced draft fan flaps malfunctioning For removing excess gases trapped inside the combustion chamber forced draft fan (FDF) are used for pre purging and post purging operation and are connected with a timer to shut the fan flaps. If the flaps are malfunctioning then continuous forced air will go inside the chamber, preventing the burner to produce flame causing flame failure of the boiler.

8) Any contactor switch inside Control panel is malfunctioning Boiler control panel consist of several contactors and PLC cards. Even one contactor malfunctioning may result in trouble for boiler starting. 9) Trip not reset If any previous trips like low water level, flame failure, emergency stop etc. has not been reset than boiler will not start. 10) Main Burner atomiser is clogged Main burners consist of atomizer for efficient burning of fuel. If the atomizer is clogged by sludge and fuel deposits then burner may not produce flame and trip the boiler.. 11) Pilot Burner nozzle is choked : A Pilot burner nozzle is very small and can be blocked by carbon deposits and sludge resulting in flame failure. Some pilot burner consists of small filter which can be clogged after continuous operation resulting in flame failure because of carbon accumulation. 12) Electrodes are not generating spark

Initial spark for generating a flame is produced by electrode which may be due to carbon deposits on them or fault in the circuit of electrodes etc. Operating Faults in Turbochargers Exhaust Gas Temperature too High Causes and Remedies: • • • •

There may be faults in engine fuel injection system (i.e.) more fuel injection .The remedy is to adjust correct fuel timing according to manufacturer. Insufficient air in the combustion chamber for combustion. Turbocharger filter may get chocked or blocked. For this, clean the filter of the turbocharger. Compressor or turbine of turbocharger may get contaminated. The remedy is to clean the compressor side and turbine side of turbocharger. Exhaust gas back pressure too high. This may be due to high carbon deposits in exhaust gas duct and in nozzle ring. The remedy is to clean the carbon deposits in the exhaust gas duct. • Turbine blade is damaged or eroded. In case the turbine is eroded the only remedy is to replace the turbine blades and rotor of turbocharger. • Cover ring may be eroded. The remedy is to clean it if possible or to replace it. • Charge air cooler may be dirty due to carbon deposits in tube fins due leaky labyrinth seal in turbocharger. The remedy is to clean the copper fins around the tubes. • Insufficient cooling water through charge air cooler. The cooling water inlet valve may be throttled by mistake. The remedy is to open the valve fully (if it is throttled) or to top off the cooling water system.

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Charge air cooler cooling water inlet temperature is too high. Check the temperature of cooling eater and clean the cooling system. • Insufficient ventilation around the turbocharger. The remedy is to improve the ventilation by running a blower or ventilation fan in an enclosed atmosphere. Turbocharger Worked Under High Exhaust Temperature

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Charge Air Pressure too Low

Causes and Remedies: •

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Leakage in the exhaust gas duct between engine and the turbine. The remedy is to locate the leak and to repair it. • Fuel injection may be incorrectly adjusted. The remedy is to adjust the fuel injection timing correctly. • Manometer indication may be defective. Check the correct functioning of manometer and if it is found defective replace the manometer. • Leak in the line to the manometer. The remedy is to repair the leak. • Dirt in the air filter causing pressure drop. Clean the filter. • Dirt in compressor and turbine of turbocharger. Clean compressor side and turbine. • Labyrinth seal leaking or damaged. Consult the service station for replacement. • Turbine blades and compressor impeller damaged. Replace the rotor. While replacing the rotor, ensure that the rotor is dynamically and statically balanced. • Nozzle ring damaged. The remedy is to replace it. • Cover ring eroded. The remedy is to replace it. • Exhaust gas back pressure too high. The remedy is to clean the exhaust gas silencer. • Charge air cooler is dirty. This can be found by the pressure drop across the charge air cooler. The remedy is to clean the charge air cooler. Charge Air Pressure is too high Causes and Remedies: •

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The main reason is that engine performance is higher than normal. The remedy is to check the engine performance and reduce it to normal. • Fuel injection system incorrectly adjusted. The remedy is to adjust it correctly. • Manometer indication may be incorrect. Check the correct functioning of manometer and if it is found defective replace it. • Nozzle ring is dirty or partly obstructed. The remedy is to clean it. Vibration of Turbocharger Causes and Remedies: •

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Rotor of the turbocharger is unbalanced due to heavy contamination of compressor side and turbine blades. The remedy is to clean the compressor side and turbine side either by water washing or by dry cleaning and it is better to call service station if the vibration is abnormal. Turbine blades or binding wire in turbine blades is damaged. Replace it. One of the turbine blades may be broken or eroded too much which may cause the rotor to become unbalanced due to variation of centrifugal force acting in various blades during operation. The remedy is to remove the blades which are broken and also remove the opposite blades to the broken blades thereby equalizing the centrifugal force acting on the rotor. The bearing may be misaligned. Seek possible cause or replace the bearing.

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Noise on Running Down, Time too Short, and Reluctant Starting Causes and Remedies: • • • •

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Bearing is damaged. The remedy is to replace the bearing with the manufacturer. Rotor is rubbing. Call service station personnel if it unable to find the fault. Dirt in turbocharger. Clean it either by dry cleaning or by water washing. The labyrinth seal is damaged. This is a whistling sound and is more specific than the remaining sounds. If you hear this sound call the service station to repair labyrinth seal. Constant Surging of the Turbocharger Causes and Remedies: •

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Increased flow resistance due to dirt in the charge air cooler or heavy deposits of dirt in the compressor and turbine blades. The remedy is to clean both the compressor side and turbine side of the turbocharger either by using dry cleaning methods or by water washing (wet cleaning). Defective check valves in a two stroke engine. The remedy is to replace the valves. Exhaust gas pressure increased after the turbine because the exhaust gas silencer is dirty. The remedy is to clean it.

iesel Generators – Troubleshooting Cooling System Issues Diesel Generators can have issues with the cooling systems. Here we offer advice for on site checking of what to check before calling an engineer. Operator’s Maintenance The most important link in the maintenance chain is the engine operator. His daily and weekly checks of the cooling system and reports on any questionable conditions he observes will help prevent engine breakdown on the job and provide valuable information to engine repair people. Each must be recorded and reported as and when they are found.

Diesel Generator Checks Before Start-up 1. Water level. 2. Cleanliness of coolant. 3. Radiator cap gasket. 4. Hose and connections for leaks or hose collapse. 5. Engine lubricating oil level. Note Oil level too low or too high will cause overheating and possible loss of the coolant. 6. Check for water in the oil and vice versa. 7. Inspect the fan for bent or damaged blades. 8. Check the belt for tension and condition. 9. Inspect the radiator for bent core fins or accumulation of debris. Check shutters for damage or linkage wear. 10. Check for leaks at the cooler, water pump, or other accessories. Diesel Generator Complaints and Causes Loss of coolant due to external leakage. 1. Leaking pipe plugs, such as core plugs, which seal off coolant passages. 2. Loose clamps, faulty hose and piping. 3. Leaking radiator: Core hole plugs are sometimes loosened by corrosion or vibration. These same conditions, or frozen coolant, can cause core seals to open up. 4. Leaking radiator, de-aeration top tank or surge tank. 5. Leaking gaskets due to improper tightening of cap screws, uneven gasket surfaces or faulty gasket installation.

6. Leaking drain cocks. 7. Leaking water pump: Badly worn or deteriorated seals are the cause of leaks at the pump. Premature failure of the pump seals often results from suspended abrasive materials in the cooling system, or excessive heat from lack of coolant or cavitation. 8. Leaks at engine cylinder head gasket. 9. Leaks at upper cylinder liner counter bore. 10. Leaking engine or auxiliary oil cooler. 11. Leaking air intake after cooler (intake air heater in some cases). 12. Leaking water manifold and/or connections. Loss of Coolant Due to Internal Leakage 1. Leaking engine cylinder head gasket: Coolant passes into the cylinders or the crankcase. 2. Cracked engine cylinder head: Coolant passes into cylinders and is blown out of the exhaust. 3. Deteriorated, severed or chafed liner packing; defective liner packing bore: Coolant passes into the engine crankcase. 4. Improperly seated or defective sleeves: Coolant can pass into the cylinder, crankcase, and, if the heads have cylindrical injectors, coolant can enter the fuel system if it gets past the injector body O-ring. 5. Porous cylinder block or head casting: Coolant can pass into the crank case via holes in the system jacket. If the cylinder heads have internal fuel passages, coolant can enter the fuel system via holes in the wall of the fuel rifle which adjoins coolant passages. 6. Cracked or porous water cooled exhaust manifold and faulty manifold to head mounting gaskets. Coolant passes into the cylinder or out through the exhaust system. 7. Leaking engine or accessory oil cooler: Coolant passes into the oil side of the cooler when the engine is shut down. The reverse almost always occurs when the engine is operating. 8. Leaking engine air intake after cooler or intake air heater: Coolant passes into the cylinders on naturally aspirated engines, also on turbo charged engines when the intake manifold pressure is less than the coolant pressure. Loss of Coolant Due to Overflow 1. Over filled radiator: As the engine reaches normal operating temperatures, the coolant expands, and due to a lack of expansion space, unseats the pressure cap or relief valve, allowing the coolant to pass out through the overflow pipe. This does not occur with a properly designed top tank – expansion space compensates for this. 2. Slush freeze or frozen coolant resulting from insufficient antifreeze in the system or poor mixing of antifreeze and water. 3. Dirt, scale or sludge in the cooling system. 4. Plugged radiator core. 5. Restriction or plugging of fill line due to routing and/or deterioration. 6. Combustion gas entering the cooling system and displacing the coolant causing it to overflow. 7. More water introduced in the area above the baffle than the fill line can handle. 8. Improperly routed or sized fill line. 9. Excessive air intake temperatures.

Diesel Generator Engines Overheating 1. Poor circulation of coolant caused by collapsing of soft hose and restriction. 2. Over fuelling the engine. 3. Radiator shutter malfunction or improper adjustment of the thermal controls. 4. Incorrect adjustment or malfunction of variable pitch or modulating fans. 5. Crankcase oil level too high: Crankshaft dips in oil and causes a corresponding increase in temperatures due to friction and parasitic load on the engine. Crankshaft oil dipping can also be encountered when operating an engine beyond the angles for which the oil pan was originally designed. 6. Dirty engine exterior: Heavy accumulations of dirt and grease can severely hinder normal heat dissipation through the exterior walls of all the engine components. 7. Pressure of air in the cooling system: The following are the most common causes of air entrapment:A. Low coolant level due to leaking water pump or leaks at hose and/or coolant accessories. B. Leaking air intake aftercooler. C. Leaking engine or air compressor cylinder head gasket. D. Improperly seated injector sleeve. 8. Inadequate cooling capacity: This condition can be the result of misapplication of one or any combination of the following cooling system components:A. Radiator B. Top Tank C. Surge Tank D. Fan E. Fan Shroud F. Water Pump G. Auxiliary Coolers H. Re-circulation Baffles I. Fan Speed 9. After boil: Coolant boils and overflows after the engine is abruptly shutdown following heavy loading. 10. Improper fan belt tension. Coolant Contaminated with Combustion Gases 1. Cracked cylinder head. 2. Blown head gasket. 3. Injector sleeves leaking. Coolant Contaminated with Fuel Oil 1. Injector sleeves leaking. 2. Porous cylinder head casting: The fuel enters the cooling system through holes in the wall of the fuel rifle which adjoins the coolant passages. Diesel Generator -WATER PUMP

Coolant Circulates at High Pump Speed Only 1. Badly deteriorated water pump impeller: Impeller damage is primarily caused by corrosion and cavitation erosion. 2. Excessive impeller to body clearance. 3. Loose water pump drive belts. 4. Impeller slipping on the shaft. 5. Cracked impellers. Fan or Water Pump Belts Break Prematurely 1. Foreign material falls in drive. 2. Shock or extreme overloads. 3. Belt damaged on installation by localised stretching. 4. Belts not properly matched. 5. Pulley mis-aligned. 6. Pulley nicked or rough. 7. Guard or shield interfering during operation. Engine Operates Too Hot or Overheats When Loaded and Coolant is Known to be at the Proper Level 1. An altered horsepower rating of an engine or new engine installation which exceeds the original design of the cooling system. 2. Clogged radiator air passages. 3. Damaged radiator core fins. 4. Heat exchanger element which contains heavy lime and scale deposits. 5. Thermostat not opening fully. 6. Fan shrouding missing, damaged, or improperly positioned with respect to the fan. 7. Re-circulation baffles on the sides of the radiator missing or damaged. 8. Fan drive belts slip: Impeller slips on the water pump shaft. 9. Clogged coolant passages, radiator, and engine. 10. Faulty automatic radiator shutters: Shutters only open partially or open too late. 11. Faulty thermatic or modulated fan drive: Fan engages too late or operates too slowly. 12. Faulty variable pitch fan: Fan operates with the blades at an insufficient pitch. Diesel Generator Engine Coolant Temperature Too Low 1. Thermostat stuck in open position, or malfunctions, to allow premature opening. 2. Thermostat seal lip deteriorates and hardens allowing the coolant to bypass the closed thermostat and enter the radiator. 3. Excessive bypassing of coolant to the radiator, with the thermostat closed and properly sealed. 4. Engine is exposed to very low temperatures and high wind with a low load factor. 5. Water through the core due to a leaking de-aeration baffle. Diesel Generator Lack of Temperature Control or indicators? 1. Defective Thermostat: Thermostat fails to open at the proper coolant temperature range and/or does not open completely. 2. Defective Thermostat Seal: Coolant leaks by the seal and onto the water pump; therefore

bypassing the radiator. 3. Operating engine having a pressurised cooling system without a pressure cap, with a defective pressure cap or a defective self-contained relief valve. Clogged Water Filter Element 1. Contamination of the coolant caused by soluble oil, engine lube oil, engine fuel, or rust, scale and lime. 2. Contamination of the cooling system with dirty fill or make-up coolant. 3. Use of anti-leak additive. Corrosion, Rust and Scale Build-up Occurs in the Cooling System even after the Water Filter is Serviced Regularly 1. Insufficient water filter capacity. 2. Improper water filter installation. 3. Careless servicing of the water filter. 4. Aeration of the coolant: Free oxygen and carbon dioxide contained in the air are highly corrosive. Rapid Loss of Proper PH Value and Inhibitor Level of Coolant 1. Dilution of the water filter concentration caused by too frequent adding of make-up coolant to the cooling system. Auxiliary Components Oil overheats even though the cooling system has adequate capacity and is free of defects. 1. Clogged or restricted oil cooler passages. 2. Restricted oil cooler and return lines. 3. Restricted oil cooler supply and discharge lines. Low Oil Pressure 1. Oil overheated. 2. Improperly baffled oil cooler tube bundle. 3. Low oil level. Abnormal Sludging of the Engine Lube Oil Resulting in Oil Cooler Clogging 1. Engine operates constantly at below normal coolant temperature or reaches the normal operating temperature too slowly. 1. Antifreeze leaking into oil pan. NOTE:In short; a maintenance contract with a reliable company will avoid most of the about issues.

Operational Faults Due To Faulty Oil System Let us discuss some thing regarding the oil system and it effects on engine performance

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1.Difficulty in crank case lubrication: a) Insufficient Oil Pressure in crank case Lubrication: As we have discussed earlier that the oil pressure has to maintained for the proper lubrication in the Marine Diesel Engine. As the lubrication fails it give rises to the operational faults ultimately failure of the system and the bearings in crank case Possible causes: 1.Defective oil pump. 2.Inadequate delivery rate of the oil pump. The prescribed delivery rate should be adhered to. 3.The by-pass in the installation is opened too far. 4.The oil regulating valve is not opened far enough. 5.Excessive bearing clearances. 6.Defective oil supply pipes. 7.Defective crosshead lubrication system. 8.The oil level in the tank has fallen too low. The oil pump is drawing-in air. b) Crank case Lube Oil supply is interrupted:

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As we know the oil flow should not be interrupted by any means if it does it result in the Operational faults. Possible causes: 1.Oil passage or grooves are obstructed. 2.Defective oil supply pipes. 3.There is air in the oil supply pipes.

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2.Difficulty with cylinder lubricating system: Possible causes: 1.The non-return valve for the lubricating stud is defective. 2.The cylinder oiler or its driver is defective. 3.Lubricating oil pipes or pipe connection is defective. 4.Lubricating oil pipe, or cylinder lubricating studs, is defective. 5.The cylinder lubricators need replenishing. 6.There is air in the piping.

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3.Difficulty with the fuel system of the engine: a) Fault in : Preheater, Filter, and Fuel pipes remain cold as a state which applies particularly to operation on heavy fuel oil. Possible causes are : 1.No steam pressure. 2.Steam pipes obstructed. 3.Failure of the steam pressure-reducing valve. 4.Condensate accumulating in the heating pipes. 5.Water accumulation in the steam trap. 6.Inadequate venting of the heating pipes. b) Fault in : Fuels do not Circulate and Unheated portions remain cold: A state which applies particularly to operation on heavy fuel oil. Possible causes are: 1.Fuel circulating pump is defective, or out of service. 2.Fuel tank is empty. 3.Fuel cannot be pumped because of inadequate heating. 4.Shut-off valves or change-over cocks, before or after the fuel circulating pump, are either closed or else set wrong way. 5.Fuel pumps inadequate vented. 6.Fuel pipes clogged by congealed fuel. When the fuel delivery pipes are obstructed, the engine should be barred over with the turning gear for several revolutions, with maximum fuel charge and the priming plug open. 7.Individual fuel pipes inadequately heated or not heated.

EFFECTS OF LOW QUALITY ENGINE SYSTEM OIL ON SHIPS

Importance of Oil Quality We have been studying about marine diesel engines and know that lubricating oil system is an important part of the engine system. The properties of lubricating oil need to be maintained within the specified parameters, in order to the engine to operate smoothly and efficiently. In this article we will take a look at the hazards of low

quality engine system oil. I am sure you know what viscosity is and what its relevance to engine running is. Regarding the quantity of engine oil, the empirical rule states that the amount of system oil depends on the type of engine. It should be 1lit/bhp and lube oil should not circulate more the 15 times/hr. •

If very low quality of system lube oil is maintained in circulation, function of lubrication will be disturbed.

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Less amount of lube oil in circulation causes rise in temperature thus reducing the viscosity leading the failure of boundary lubrication due to decrease in oil film thickness.

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Insufficient time for de-aeration and it accelerates the process of oxidation of oil .Due to oxidation

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Lubrication oil properties are lost

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Forms sludge and high temperature sludge adhere to metal surface.

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Formation of acids/corrosive attack.

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Increase the viscosity of oil.

4. Increase in friction, wear, heat corrosion, contamination and noise and it reduces the engine performance to critical and in extreme cases total shut down of engine operation. 5. Also other properties of lubricating oil will be lost sooner as the additives will deteriorate faster. Problems Associated with Lube Oil Viscosity Change EFFECTS: •

Unable to form a lubrication film and losing the lubricating property.

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Increase in friction and wear and bearing damage.

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Overheating due to break down of lube oil film.

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Acid corrosion occurs if contaminated by high sulphur content HFO.

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Contamination with diesel oil reduces the flash point.

CAUSES FOR THE CHANGE: •

Fuel contamination – viscosity increases due to HFO and the viscosity decreases due to DIESEL OIL contamination.

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Contamination of insoluble like carbon from blow past.

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Oxidation-Increase viscosity.

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Contamination by other lubrication-Due to accidental topping up of wrong grade of lube oil.

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Less quantity of lube oil in circulation.

CORRECTIVE ACTION: •

Preheating of lubricating oil before purification for effective functioning of purifier.

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Purifier efficiency reduces contamination of insoluble and water regularly clean the sludges formed in purifier.

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Sufficient quantity of lube oil in circulation.

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Proper cooling of lube oil before sending to the engine.

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After circulation for the certain running period “BATCH PURIFICATION ” is done.

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Carry out shipboard lube oil test.

What do you mean by “BATCH PURIFICATION”: •

Originally the term batch purification applied only to the purification of MAIN ENGINE crank case lube oil.

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Batch purification referred to the system whereby the engine is shut down and the whole of sump lube oil charge is pumped up to the dirty lube oil tank in the upper part of the engine room.

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The lube oil is heated in the tank and left as long as possible to settle out solids, sludges and any water.

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It is then slowly purified in one batch, hence the name.

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It is generally done in port where main engine is not running. While running of main engine we cannot do the batch purification because the regular continuous purification will be going on.

Ship Board Lube Oil Test Qualitative oil test carried out in board ship do not give a complete and accurate picture of the condition of lube oil .This could be obtained in a laboratory.

However they do give good enough indication of the oil to enable the engineer to decide when the oil should be replaced or if some alteration in the cleaning procedure is considered necessary. Test for Alkalinity, Depressiveness, contamination, water and viscosity are usual. Samples of oil should be taken from the main supply line just before entry into engine since it is the condition of the oil being supplied to the engine that is of the greatest important.

Functions and Properties of Lubricating oil on Ships What are the functions of a lubricant? •

Separate entirely the contact surfaces, thereby reducing static and dynamic friction to least possible value to prevent wear and tear.

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Remove heat generated within the bearing.

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Protection of the working surfaces against corrosion.

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Removal of contaminants.

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Dampen noise produced.

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Act as a sealant.

What are the Types of Lubrication on Ships? •

Hydrodynamic Lubrication or Full fluid film lubrication.

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Boundary Lubrication or Thin film lubrication.

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Hydrostatic Lubrication or Thick film lubrication.

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Elasto-hydrodynamic Lubrication or Thin film or square film lubrication.

What are the Properties of crankcase lubricating oil? •

Viscosity: To be suitable for the purpose

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Viscosity index: To be high

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Pour Point: Must be low

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Flash point: Must be high

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Oxidation stability: To be high

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Carbon residues: To be low

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Total acid number or TAN: To be suitable for the purpose

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Total basic number or TBN: To be suitable for the purpose

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Detergency: For cleaning

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Dispersancy: To facilitate purification

What is viscosity? •

It is a measure of internal resistance to flow between liquid layers.

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Viscosity of lube oil reduces when temperature rises and vice versa.

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For engine crankcase lube oil, viscosity is 130 to 240 Redwood No-1 seconds 60°C.

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For cylinder oil, viscosity is 12.5 – 22 Cst

What is viscosity index? •

It is the rate of change of viscosity of an oil with respect to change in temperature.

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An oil with low viscosity index has greater change of viscosity with change in temperature.

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An oil with high viscosity index has very little change of viscosity with change in temperature, which is a desirable property for lubricating oil.

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For crankcase oil, viscosity index is 75 to 85.

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For cylinder oil, viscosity index is 85.

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Viscosity index of mineral oils is highest, about 115 and this may be raised to about 160 by adding special additives.

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Hydraulic oils should have high viscosity index for faster response of the system. It is usually around 110.

What is a pour point?

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It is the lowest temperature below which an oil will stop flow.

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Pour point indicates that oil is suitable for cold weather or not.

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Pour point of engine crankcase should be -18°C.

What is the flash point? •

It is the lowest temperature at which the oil will give off a sufficient inflammable vapour to produce a momentary flash when a small flame is brought into the surface of the oil.

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Close flash point for crankcase lubricating oil is around 220°C.

Why flash point is important? •

Fuel oil flash point is to be high because if it is low, there would be a possibility of fire in storage.

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Engine crankcase lubricating oil flash point should be as high as possible to prevent crankcase explosion.

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For safe storage, oil storage tank heating temperature to be limited to at least 14°C lower than flash point to prevent fire.

Average Closed Flash Points •

Petrol = -20°C

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70cSt Fuel Oil = 71°C.

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Paraffin = 40°C

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Lube Oil = 220°C

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Diesel Oil = 65°C

What is Total Acid Number or TAN and Total Base Number or TBN? •

The ability of an oil to react with a base reagent which indicates the acidity is expressed as TAN.

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The ability of an oil to react with acidic reagent which indicate the alkalinity is expressed as TBN.

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The results are expressed in milligrams of potassium hydroxide (KOH) required to neutralise one gram of sample oil for both TAN and TBN.

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TBN for an oil used for cross head type diesel engine crankcase is 8mg KOH/gram of oil.

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TBN for an oil used for trunk type engine using heavy oil is 30mg KOH/gram of oil.

What type of engine are using high TBN and why? If blow pass occur in a trunk type engine using heavy fuel oil, incomplete combustion products reach directly into the crankcase and may cause the contamination of lube oil with acid. Thus in this type of engine to neutralize the acid contamination must be used high TBN oil. What is detergency and dispersancy ? •

It is a chemical additive called detergent which has a property of preventing the deposition of carbon deposits and wash away with the lube oil.

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Dispersant additive is added to divide the larger size deposits into tiny particles to be carried in a colloidal suspension evenly throughout the bulk of oil, which can be removed while filtration of the oil.

Explain the L O sampling procedure to send for LO test ? •

The sample should be drawn with oil circulation with the system such as a test cock on the discharge side of the LO oil pump.

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Before taking the sample oil sufficient amount of oil should be drain out to clear the line.

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The sample is filled into the chemically cleaned container after it is rinsed with the sample oil and immediately closed.

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The container should be attached with information on engine type, engine running hours, LO running hours, fuel used, draw off point and date of sampling.

Explain Sampling Procedure of lube oil? •

Draw samples from a connection that comes directly out of the main oil supply line to the engine.

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Always sample for the same point.

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Sample only when the oil is up to its operating temperature with the engine running.

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Depending upon the draw off point, sufficient amount of oil should be drained out of the line prior to drawing the sample.

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The sample should be filled into a chemically cleaned container after it is rinsed with sample oil and immediately closed.

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The container should be attached with a label as follows:

Records for Sample •

Date of sample drawn

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Point of sample drawn

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Type of oil

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Type of machinery use

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Temperature of sample drawn

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The period of time since the last renewal of oils.

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Avoid sampling from places where the oil may be stagnant or have little or no flow, such as sumps, auxiliary smaller pipelines, purifier suction or discharge lines, drain cocks of filters, coolers etc.

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Also avoid sampling while engine is stopped.

What is the essential factor effecting the establishment of hydrodynamic lubrication ? •

Viscosity of lube oil

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Load acting on the bearing

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Surface smoothness of moving parts

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Speed of rotation

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Continuous LO supply

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Bearing clearance, bearing length and pin diameter.

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There must be convergence between fixed end and moving surface.

Where do locate ME LO sump and its fitting ? •

It is located under the main engine in the ship double bottom and surrounded by cofferdams.

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It consist of 1) level gauge 2) man holes 3) air vent pipe 4) sounding pipes 5) heating steam coils 6) suction pipe and 7) valves for LO p/p and purifier.

Why magnetic fitter is fitted on LO system and where is it fitted ? •

To prevent pump damage due to ferrous metal particles.

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Screw p/p used in LO oil system is working in very fine clearance thus to prevent entering the small ferrous particles into the p/p.

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Magnetic fitter is fitted prior to the main circulation LO p/p.

What are the contaminants in the lube oil ? •

Contamination of fresh Water (JW leaking)

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Contamination of SW (Cooler leakage)

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Contamination of fuel (Poor Atomisation, Unburned Fuel)

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Oxidation products (High Exhaust Temperature, Burned Cyl Oil, Carbon from incomplete combustion)

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Products of fuel combustion

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Foreign mineral matters (Scale formation, Wear and tear)

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Biological contamination.

What are the effects of water contamination in lube oil ? Causes •

Condensation of water vapour within the crankcase

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Leakage from the cooling water system for cylinder or piston

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Leakage from the sump tank heating steam coils.

Effects •

Reduce cooling efficiency.

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Increase the acid formation in trunk type piston engine.

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Can cause corrosion on m/c parts.

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Microbial degradation, [Reduce centrifuging efficiency; promote local pitting and corrosion]

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Reduce load carrying capacity

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Reduce L.O properties, and TBN of oil

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Form sludge due to emulsification

Remedies •

Proper purification with minimum throughput

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Batch purification if heavy contamination

Maximum Allowable Amount of water in Lube oil? •

For crosshead type engine , < 0.2 % is satisfactory

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If water content exceed 0.5 ~ 1.0 %, immediate action should be taken

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If > 1%, engine can be damaged

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For trunk type engine , < 0.1% is satisfactory

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If > 0.5 %, immediate action should be taken and

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It is maximum permissible content

What are the effects of fuel dilution in lube oil ? Causes •

Poor atomization of a fuel injector and back leak through the fuel injector p/p plunger and barrel.

Effects •

Fuel dilution usually diesel oil.

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Lower viscosity and low fresh point

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Lower viscosity LO reduces this properties ( e.g load carrying capacity )

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Lower fresh point will case crankcase explosion.

How to remove contaminants

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Filtering: Removes large oil insoluble matter

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Gravity separation: Removes heavy matters, sludge and water

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Adding special additives: Reduce acids, sludge, finer oil insoluble matter

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Centrifuging: Removes sludge, foreign matter and water

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Water washing: Only for straight mineral oil or oil without additives, can remove acids.

What will you do if LO is contaminated with FW or SW ? •

Batch Purification must be done

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Renovating Tank heating and regular draining

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For SW contamination, Water Washing is required

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Sump to be opened and thoroughly wipe out.

What is meant by batch purification ? •

Firstly take the immobilization permit from the port authority.

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The entire oil charge should be pumped by the purifier or by main circulation p/p into settling tank.

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It should be allowed to settle for at least for 24 hours with heating about 60° C .

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Water and sludge should be drained out periodically.

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Cleaned the interior of the sump tank and carefully examined.

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The oil should be passed through the purifier at its optimum efficiency and than pump back into the sump tank.

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When sump tank empty, its interior should be cleaned and examined.

When do periodic batch purification make ? •

If the oil is suspected from containing strong acids

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High insoluble contents due to poor combustion or water due to leak cooling system.

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It is also made at least once a year when cleaned and examined for sump tank.

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Suspecting biological contamination.

What is grease ? •

It is a semisolid lubricant consisting of high viscosity mineral oil and metallic soap with filler.

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Metallic soaps are compound of Ca, Na, Al.

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Filler are lead, zinc, graphite and molybdenum.

What is solid lubrication ? •

Grease lubrication is known as solid lubrication

At what point cylinder oil is injected ? •

The cylinder oil is feed to the piston at the time when the top two piston rings pass the lubrication holes in the cylinder during the piston stoke.

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It is a limited lubrication.

What will be happen temperature is lower than pour point ? The oil can not freely flow thus effect the pumping system (lubrication system) Why viscosity of lube oil is important ? •

Low viscosity is required for fuel oil in order to obtain good atomization at fuel.

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Lube oil must be chosen which has a suitable viscosity for the working temperature for efficient lubrication.

How to maintain lube oil on board ships? •

L.O onboard test is carried out regularly.

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Regular cleaned L.O line filter.

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L.O purifier should be run during ship is in sea

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Maintain L.O purifier performance

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Periodic batch purification must be carried out & cleaned L.O sump tank once a year

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Maintain L.O temperature within limit

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Maintain good L.O cooler efficiency

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Keep good fuel combustion system

Why lubricating oil cooler is installed after lube oil filter ? •

It is more effective to filter the hot oil, as pressure drop through the filter is less and filter is more efficient.

What will you do as 2/E, if main engine lubricating oil temperature abnormally high? •

Inform bridge & reduce engine speed

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Check engine overload or not (Exhaust temp:, fuel rack,..)

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Check L.O sump & L.O cooler & L.O purifier temperature (set value)

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Check L.O sump tank heating valve.

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Shut L.O cooler by-pass totally after stopping (or) too high temperature not fall

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Clean L.O cooler

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Check sump tank heating coil leakage

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Make L.O onboard test (esp Viscosity)

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Check lubricating oil piping system leakage or blockage

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Make inspection & check bearing clearance & loosing attachment

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Check ampere (or) load when turn the turning gear

What will you do as 2/E, when increase sump lubricating oil level by marine engineer? •

Check piston cooling system (water)

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Check L.O purifier (gravity disc is correct or not) [L.O purifier water outlet sight galss]

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Check filling valve from storage tank

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Check L.O cooler/although oil pressure is greater than sea water pressure.

What will you do as 2/E, when decrease in sump lubricating oil level by marine engineer? •

Check rate of decreasing if slowly decrease, fill up L.O and find the leakage without stopping engine.

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If rapidly decrease, inform to bridge and stop the engine. Find the leakage and repair. Possible leakage points are:

* Bed plate crack (check engine room bilge) * Piston cooling L.O system (check scavenge space & under piston space {entablature}) * L.O cooler & L.O purifier * All pipes and connection * Check L.O return valve from crankcase to sump tank close or not * Check oil scraper rings & stuffing box What will you do as 2/E, when decrease in lubricating oil pressure observed? •

Start stand by pump

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Change & clean L.O filter

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After engine stopping, check bearing clearance and L.O pipe connection

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Check L.O pump discharge & suction pressure

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Check L.O temperature

What is meant by hydrodynamic lubrication (full fluid film)? •

Moving surfaces are separated completely by the pressure of a continuous unbroken film or a layer of lubricant, generated by the movement of the two surfaces relative to each other.

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Essential requirement is formation of a wedge of lubricants between surfaces.

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Thickness of film 0.025 – 0.10 mm.

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Happens in lubrication for Journal Bearing, Bottom End Bearing, Tilting Pad Thrust Bearing

What is meant by boundary lubrication? •

It exists when a full-fluid film lubrication is not possible.

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The sliding surfaces are separated by only a thin film of lubricant.

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High friction between the surfaces and some degree of metal to metal contact occurs

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Lubricant oil film decreases, until asperities of mating surfaces touch

What is meant by hydrostatic lubrication? •

A form of thick film lubrication, but instead of being self- generated, it is supplied from an external source by oil under pressure from a pump.

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Lubrication for Crosshead Bearings, with attached pump.

What is meant by elasto-hydrodynamic lubrication? •

Applies to line contact or nominal point between rolling or sliding surfaces, such as rolling contact bearings and meshing gear teeth.

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Thin film or squeeze film lubrication limits metal to metal contact.

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Elastic deformation of the metals occurs, and there is effect of high pressure on the lubricant.

What will you do as 2/E, if lube oil is contaminated with sea water? •

When sump oil is contaminated with SW, find sources of leakage (may be from LO cooler during ME stopped) stoppage and rectified.

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In port or while ME is stopped, transfer contaminated oil through purifier or transfer pump into settling tank, settled for at least 24 hours at about 60 C°, and water and sludge drained out periodically.

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Oil passed through purifier at 78° C with optimum efficiency, and pump back to settling tank.

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When sump tank is empty, interior cleaned and examined.

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Purified oil sent to laboratory and tested

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During this time, new oil should be used

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Oil should be reused, if lab results recommended that it is fit for further use. (Straight mineral oil 3% water washed. Additive oil 1% water washed).

What are the difference in Cylinder oil and System oil? •

Cylinder oil is detergent / dispersant oil

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System oil is straight mineral oil

What are the lube oil tests carried out on board Ships ? Viscosity Determination •

The simplest method is three tube rolling ball viscometer

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Assuming the oil in the engine to be SAE 30 grade, one tube is filled with minimum safety viscosity (about SAE 20) and another one filled with maximum safety viscosity (about SAE 40). The last tube is to be filled with test sample.

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All tubes are placed in a bucket of warm water until the oils are at the same temperature.

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The three tubes then mounted on a tilted board and inverted. An internal hollow ball in each tube then rises to the surface.

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If the time taken in the test sample is between that of the lower and upper limit oils, the oil is fit for further use. If not, it must be replaced.

Insoluble Content •

A drop of sample oil is released from a given height onto a special filter paper.

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Compare the result with the known varying insoluble content. The upper limit for straight mineral oil is 1% to 1.5 % and for detergent dispersant oil is 5%.

Water and other Contaminants A known amount of sample oil in the test tube is heated and must be shaken the while doing so •

If there is no cracking, the oil is dry

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If there is slightly cracking, the oil having a trace of water

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If there is a heavily crackling, the oil is heavily diluted with water

Acidity / Alkalinity Determination Acidity is tested by extracting the acids from the sample by means of shaking with a known amount of distilled water. The acidic extract is then placed on a watch glass with an indicator solution of known strength. The mixture is then drawn up into a glass tube and its colour compared with a series of colour standards, each representing a known PH value, from which the sample can be determined quite accurately.

Another method is : A drop of indicator solution is placed on to blotting paper and this is followed by a drop of sample oil placed at the centre of the drop of previous absorbed indicator. •

If the change of colour is Red, it is acid

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If blue/green, it is alkaline.

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If yellow/green, it is neutral.

Foreign Particles Test •

This can be done by either Spectrochemical analysis or Ferrographic analysis, each giving particle size less than 10 uM to 100 uM range depending on the tests applied.

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The most powerful technique is Inductively coupled plasma atomic emission spectrometry (ICP OR PES), which uses a direct spray technique to determine the wear and contaminant elements present in the oil. This technique will in the main only detect the particles below 10 uM size.

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In ferrographic test, the sample is thinned first with some solvents and allowed to pass slowly down a slide surrounded by powerful magnetic field. Then it is examined by special microscope with red and green filters under lights. The shape of the particles is used to identify the source of the wear debris.

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The advance ferrography method was added to the PFA (Progressive Fast Analysis) programme where all samples pass through the combination of two machines, a particle quantifier (PQ) and a rotary particle depositor (RPD). These test measures the induced magnetic moment of debris as deposited on a substrate or contained within a specific volume of liquid.

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These machines provide accurate test by rotating the metal particles and then separating into three different sizes, Theses three bands of particles are examined by very powerful microscope to determine the type of materials and shape.

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If more detailed examination is necessary, the debris may be subjected to a scanning electron microscope.

+ Lubricating oil system

Lubricating oil for an engine is stored in the bottom of the crankcase, known as the sump, or in a drain tank located beneath the engine . The oil is drawn from this tank through a strainer, one of a pair of pumps, into one of a pair of fine filters. It is then passed through a cooler before entering the engine and being distributed to the various branch pipes. The branch pipe for a particular cylinder may feed the main bearing, for instance. Some of this oil will pass along a drilled passage in the crankshaft to the bottom end bearing and then up a drilled passage in the connecting rod to the gudgeon pin or crosshead bearing.

An alarm at the end of the distribution pipe ensures that adequate pressure is maintained by the pump. Pumps and fine filters are arranged in duplicate with one as standby. The fine filters will be arranged so that one can be cleaned while the other is operating. After use in the engine the lubricating oil drains back to the sump or drain tank for re-use. A level gauge gives a local read-out of the drain tank contents. A centrifuge is arranged for cleaning the lubricating oil in the system and clean oil can be provided from a storage tank. The oil cooler is circulated by sea water, which is at a lower pressure than

the oil. As a result any leak in the cooler will mean a loss of oil and not contamination of the oil by sea water. Where the engine has oil-cooled pistons they will be supplied from the lubricating oil system, possibly at a higher pressure produced by booster pumps, e.g. Sulzer RTA engine. An appropriate type of lubricating oil must be used for oil-lubricated pistons in order to avoid carbon deposits on the hotter parts of the system.

Cylinder lubrication Large slow-speed diesei engines are provided with a separate lubrication system for the cylinder liners. Oil is injected between the liner and the piston by mechanical lubricators which supply their individual cylinder, A special type of oil is used which is not recovered. As well as lubricating, it assists in forming a gas seal and contains additives which clean the cylinder liner.

Lubricating Oil Sump Level The level of lubricating oil indicated in the sump when the main engine is running must be sufficient to prevent vortexing and ingress of air which can lead to bearing damage. The sump level is to be according to manufacturers/shipbuilders instructions . The ‘Sump Quantity’ is always maintained at the same safe operating level and is given in litres. It is essential that the figures are mathematically steady and correct from month-to-month, taking into account consumption, losses and refills and reported . The ‘Sump Quantity’ is calculated with the engine stopped, but the lubricating oil pump in operation, thus keeping the system oil in circulation. Sufficient reserve quantities of lubricating oil must always be held, i.e. to completely fill the main sump and sufficient quantities of other lubes must be held to cover the intended voyage plus 20%. Lubricating oils are a major expenditure item, therefore, all purchasing must be pre-planned with the

aim of buying the maximum amounts from the cheapest supply sources which are primarily the US, Europe and Singapore. Lub oil requisitions should be sent to the office at least 10 days before the intended port of purchase and clearly indicate if the vessel requires supply in bulk or in drums.

Pre-Lubrication Pumps They provide an essential part of the lubrication system on many types of engine in particular auxiliary engines with engine driven lubricating oil pumps. They provide a supply of oil to the bearings prior to start up and limit the length of time that boundary lubrication exists, and shorten the time when hydrodynamic lubrication commences. They must be maintained and operated in accordance with the manufacturers’ instructions. Cooling Water Treatment for Diesel Engines on Ships Quality of Cooling Water The cooling water of the engine should be only demineralized (distilled) water with proper treatment, which is necessary for keeping effective cooling and preventing corrosion of the system. Though the distilled water matches best to the requirements for cooling water, it is necessary to add corrosion inhibitor. Because untreated distilled water absorbs carbon dioxide from the air and then becomes corrosive. Sea water or fresh water contaminated by sea water even in small amount is not allowed to be used as cooling water of the engine due to high risk of severe corrosion and deposits formation in the system. Rainwater is heavily contaminated and highly corrosive in general, which is also not recommended as cooling water. Tap water (drinking water) is not recommended as cooling water due to risk of chalk deposit formation inside the cooling system. However, if the distilled water, for example from fresh water generator, is not available, tap water may be used as cooling water after softening and some other treatments according to the ingredients. The cooling water before adding corrosion inhibitor should be checked and treated to satisfy following requirements:

pH Total hardness as CaCOз Chloride Sulphate Silicate Residue after evaporation

7 to 9 max. 75 ppm(mg/l) max. 50 ppm(mg/l) max. 100 ppm(mg/l) max. 150 ppm(mg/l) max. 400 ppm(mg/l)

Note: Chloride and Sulphate are corrosive even in the presence of an inhibitor. Treatment of Cooling Water Cooling water should be treated properly and corrosion inhibitor should be added. The analysis and treatment of cooling water are recommended to be carried out by a famous and familiar specialist. Otherwise, keep the treatment procedures strictly according to the instructions from the supplier. Some recommended products are listed as follows:

Note: Oily inhibitors adhere to cooling surface and influence cooling efficiency, which are not recommended for cooling water. Only nitriteborate based inhibitors are recommended. Note: Do not mix the inhibitors of different types or properties.

Checking Cooling Water and the System The property of the cooling water may be changed during service due to contamination or evaporation. Therefore, the cooling water itself and the system should be checked periodically during service, preferably once a week. These tests may be done by means of test kits from inhibitor maker with sample water from the circulating system. However, laboratory test of the sample water by specialist is also recommended regularly at least every three month. All checking results should be recorded and kept for trend evaluation, which contribute to reliable engine operation with right cooling water treatment. If test result shows that the contents of cooling water changes suddenly or gradually, the cooling water system should be checked to trace the cause. Some of the changes may indicate the cause as follows: Chloride content increasing: • Check possibility of seawater penetrating into cooling water. • Check the system which includes sea water, for example fresh water cooler cooled by sea water. pH value decreasing or sulphate content increasing: • Check if cooling water is contaminated by exhaust gas. • Check cylinder head by hydraulic pressure test. Note: If the quality of the cooling water after checking exceeds control limit by water treatment, the cooling water should be replaced completely by newly treated water. Cleaning of Cooling Water System If any deposit or rust is abnormally detected in the cooling water system, the system should be cleaned thoroughly and then the cooling water also should be refilled up completely by newly treated water. The cleaning of the cooling system includes degreasing and descaling procedures which need special chemicals. As the chemicals may be hazardous, the cleaning of the cooling water system is recommended to be carried out by reliable specialist firm. Otherwise it should be done strictly in accordance with instructions from the supplier of cleaning chemicals.

Note: Descaling process by acid is hazardous, which needs protective equipment for human body, for example, everybody near the system should put on protective glasses and gloves at least. Note: Careful attention is required to avoid contamination of lubricating oil by acid during descaling process. Check the acid content of lubricating oil of the engine directly after descaling work of the cooling system by acid and check again next day. Filling-Up of Cooling Water Directly after cleaning process of the cooling system, flush the system thoroughly with water until pH value to be about 7, and then drain the water. Fill up the system with distilled water until the water level of the expansion tank to have margin for treatment. Prepare the solution of inhibitor according to the instruction from the maker and add the solution into the expansion tank. Add distilled water more to the normal level of the expansion tank. Run the engine for settlement according to the inhibitor maker’s recommendation or at least for 24 hours and then check the quality of the water for confirmation. If the amount of cooling water is reduced due to evaporation or leakage or drainage for maintenance, the water level of the tank should be maintained by adding water. Water for compensating evaporation should be distilled water, while the water for loss due to leakage or drainage should be same treated water. After adding the water, checking of the quality of the water should be carried out to confirm the correct concentration of the ingredients. Replace cooling water completely with newly treated water with interval of at least every two years. Waste cooling water should be treated in compliance with governing laws.