Q: The purpose of Safety guide which definitions are generally followed in Marine Ship(Tanker).
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• Resuscitator: Equipment to assist or restore the breathing of a man overcome by gas or lack of oxygen.
• Spontaneous combustion: The ignition of materials brought about by a heat producing (exothermic ) chemical reaction within the material itself without exposure to an external source of ignition.
• Stripping : The final operation in pumping bulk liquid from a tank or pipe line.
• Reid vapour pressure: (RVP) The vapour pressure of a liquid determined in a standard manner in the Reid apparatus at a temperature of 37.8oc and with a ratio of gas to liquid volume of 4:1
• Insulating Flange: A flanged joint incorporating an insulating gasket, sleeves and washer to prevent electrical continuity between pipelines, hose strings or loading arms.
• Interface detector: An electrical instrument for detecting the boundary between oil and water.
• Petroleum: Crude oil and liquid hydrocarbon products derived from it.
• Petroleum gas: a gas evolved from petroleum. The main constituents of petroleum gases are hydrocarbons, but they may also contain other substances such as hydrogen sulphide or lead alkalies, as minor constituents.
Wednesday, June 9, 2010
Sunday, June 6, 2010
MARINE ENGINE Q&A-MAIN ENGINE SAFETY GUIDE
Q: The purpose of Safety guide which definitions are generally followed in Marine Ship(Tanker).
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A: The following definitions are applied to Marine Ship (Oil & Chemical Tanker).
• Antistatic additive: A substance added to a petroleum product to raise its electrical conductivity above 100 pico siemens/metre to prevent accumulation of static electricity.
• Bonding: The connecting together of metal parts to ensure electrical continuity.
• Clingage: Oil remaining on the walls of a pipe or on the surfaces of tank interiors after the bulk of the oil has been removed.
• Cold Work: Work which can not create a source of ignition.
• Cathodic Protection: The prevention of corrosion by electro chemical techniques. On tankers it may be applied either externally to the hull or internally to the surfaces of tanks. At terminals, it is frequently applied to steel piles and fender panels.
• Entry permit:A document issued by a responsible officer permitting entry to a space or compartment during specific time interval.
• Flash Point: The lowest temperature at which a liquid gives off sufficient gas to form a flammable gas misture near the surface of the liquid.
• Inert Condition: A condition in which the oxygen content throughout the atmosphere of a tank has been reduced to 8 percent or less by volume by addition of inert gas.
• Inert Gas: A gas or a mixture of gases, such as flue gas, containing insufficient oxygen to support the combustion of hydrocarbon.
• Gas free: A tank, compartment or container is gas free when sufficient fresh air has been introduced into it to lower the level of any flammable, toxic, or inert gas to that required for a specific purpose, e.g. hot work,entry etc.
• Gas free certificate: A certificate issued by an authorized responsible officer confirming that at the time of testing a tank, compartment or container it was gas free for specific purpose.
• Pour point: The lowest temperature at which a petroleum oil will remain fluid.
• Toxic: Poisonous to human life.
• Topping off: The operation of completing the loading of a tank to a required ullage.
• Topping up: The introduction of inert gas into a tank which is already in the inert condition with the object of raising the tank pressure to prevent any ingress of air.
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A: The following definitions are applied to Marine Ship (Oil & Chemical Tanker).
• Antistatic additive: A substance added to a petroleum product to raise its electrical conductivity above 100 pico siemens/metre to prevent accumulation of static electricity.
• Bonding: The connecting together of metal parts to ensure electrical continuity.
• Clingage: Oil remaining on the walls of a pipe or on the surfaces of tank interiors after the bulk of the oil has been removed.
• Cold Work: Work which can not create a source of ignition.
• Cathodic Protection: The prevention of corrosion by electro chemical techniques. On tankers it may be applied either externally to the hull or internally to the surfaces of tanks. At terminals, it is frequently applied to steel piles and fender panels.
• Entry permit:A document issued by a responsible officer permitting entry to a space or compartment during specific time interval.
• Flash Point: The lowest temperature at which a liquid gives off sufficient gas to form a flammable gas misture near the surface of the liquid.
• Inert Condition: A condition in which the oxygen content throughout the atmosphere of a tank has been reduced to 8 percent or less by volume by addition of inert gas.
• Inert Gas: A gas or a mixture of gases, such as flue gas, containing insufficient oxygen to support the combustion of hydrocarbon.
• Gas free: A tank, compartment or container is gas free when sufficient fresh air has been introduced into it to lower the level of any flammable, toxic, or inert gas to that required for a specific purpose, e.g. hot work,entry etc.
• Gas free certificate: A certificate issued by an authorized responsible officer confirming that at the time of testing a tank, compartment or container it was gas free for specific purpose.
• Pour point: The lowest temperature at which a petroleum oil will remain fluid.
• Toxic: Poisonous to human life.
• Topping off: The operation of completing the loading of a tank to a required ullage.
• Topping up: The introduction of inert gas into a tank which is already in the inert condition with the object of raising the tank pressure to prevent any ingress of air.
Saturday, June 5, 2010
MARINE ENGINE Q&A-MAIN ENGINE EXHAUST VALVE
Q: 1 Explain the operation of a main engine Exhaust valve which is operated hydraulically?
A: A hydraulic pump, operated by the exhaust cam supplies the hydraulic oil to operate the valve. A small permanent vent ensures that air is excluded fro the system. This leak off of oil returned to the air spring cylinder for lubrication and is then drained away. The hydraulic pump is supplied with a make up supply via a non return valve and a relief valve.
As the cam rotates in time with the crankshaft it lifts the plunger on the hydraulic pump. Oil displaced by the pump plunger displaces the exhaust valve operating piston, moving it and the exhaust valve spindle downwards against the air spring pressure and opening the exhaust valve.
The exhaust gas passes over the spinner, rotating the exhaust valve spindle, this reduces distortion due to uneven temperatures and helps remove deposits as the valve closes .when the cam passes its peak, the pump plunger moves downwards and the compressed air in the air spring closes the valve. As the operating piston enters the damping pin, the closing is slowed, thus preventing hammering of the valve.
A: A hydraulic pump, operated by the exhaust cam supplies the hydraulic oil to operate the valve. A small permanent vent ensures that air is excluded fro the system. This leak off of oil returned to the air spring cylinder for lubrication and is then drained away. The hydraulic pump is supplied with a make up supply via a non return valve and a relief valve.
As the cam rotates in time with the crankshaft it lifts the plunger on the hydraulic pump. Oil displaced by the pump plunger displaces the exhaust valve operating piston, moving it and the exhaust valve spindle downwards against the air spring pressure and opening the exhaust valve.
The exhaust gas passes over the spinner, rotating the exhaust valve spindle, this reduces distortion due to uneven temperatures and helps remove deposits as the valve closes .when the cam passes its peak, the pump plunger moves downwards and the compressed air in the air spring closes the valve. As the operating piston enters the damping pin, the closing is slowed, thus preventing hammering of the valve.
MARINE ENGINE Q&A-BEARING
Q:1 Explain how effective lubrication of the top end bearing is achieved.
A: The crosshead on a slow speed two stroke engine is very difficult to lubricate bearing effectively.The load is continually downward and because the connecting rod(con rod) swings about the pin, Changing direction each stroke, so true hydrodynamic lubrication cannot take place.Instead the lubrication starts as boundary and as the rubbing speed increases, a hydrodynamic film is built up.As the rubbing speed decreases the lubrication becomes boundary once again Oil supplied to the crosshead can be boosted in pressure to help with effective lubrication. A large pin diameter gives increased rubbing speeds, allowing the oil wedge to be built up as soon as possible.
Friday, June 4, 2010
Marine Engine-Q & A - Piston
Q: What are the faults in Marine engine Piston?
A:
1. Cracking:Cracking in piston occur in piston crown and mainly in upper piston wall.
2. Burning: Burns in piston are found in piston crown to surface.
3. Scaling: Scaling in piston is found in piston cooling chamber and passage.
4. Steeping : Steeping in piston occurs in edges of piston ring grooves.
5. Wear : Wear occurs mainly in wear ring, piston skirt and side wall.
6. Hot Corrosion: Hot corrosion on piston occurs mainly in the crown and the acidic corrosion occurs mainly
under crown
A:
1. Cracking:Cracking in piston occur in piston crown and mainly in upper piston wall.
2. Burning: Burns in piston are found in piston crown to surface.
3. Scaling: Scaling in piston is found in piston cooling chamber and passage.
4. Steeping : Steeping in piston occurs in edges of piston ring grooves.
5. Wear : Wear occurs mainly in wear ring, piston skirt and side wall.
6. Hot Corrosion: Hot corrosion on piston occurs mainly in the crown and the acidic corrosion occurs mainly
under crown
Marine Engine-Q & A - Fuel Pump
Q: Explain how a fuel pump may be checked for accuracy of injection timing.
A: With a jerk type fuel pump, injection starts when the top edge of the plunger cuts off the spill ports as the plunger is moving upwards on the delivery stroke.To check the accuracy of the start of injection, the engine crank angle for the start of injection must correspond to the manufacturers setting when the plunger is at this point.
On the some pumps it is possible, after isolating the fuel and draining the pump, to remove erosion plugs and sight through the spill ports while turning the engine.At the point where the edge of the plunger is seen to cover the top of the spill port, the crank angle for that particular unit is noted and copared with the manufacturers recommendation.
On the other hand it may be necessary to remove the cover of the pump and the delivery valve and measure the distance from the top of the barrel to the top of the plunger.The manufacturer will give the correct distance at which the plunger has covered the spill ports.Alternatively the distance to the top of the plunger when the unit is on TDC may be given
A: With a jerk type fuel pump, injection starts when the top edge of the plunger cuts off the spill ports as the plunger is moving upwards on the delivery stroke.To check the accuracy of the start of injection, the engine crank angle for the start of injection must correspond to the manufacturers setting when the plunger is at this point.
On the some pumps it is possible, after isolating the fuel and draining the pump, to remove erosion plugs and sight through the spill ports while turning the engine.At the point where the edge of the plunger is seen to cover the top of the spill port, the crank angle for that particular unit is noted and copared with the manufacturers recommendation.
On the other hand it may be necessary to remove the cover of the pump and the delivery valve and measure the distance from the top of the barrel to the top of the plunger.The manufacturer will give the correct distance at which the plunger has covered the spill ports.Alternatively the distance to the top of the plunger when the unit is on TDC may be given
Thursday, June 3, 2010
Marine Engine-Q & A - Propeller & Liner
Q: How to Hoop Stress Relief for Main Engine Propeller Hub and Shaft Liner
A: It is important that the stress relief grooves be at least 12.5 mm (1/2") deep and that the thickness of the lip at the edge be held at 1.6mm (1/16"). The side of the stress relief groove adjacent to the shaft should have an easy slope, as shown, to provide effective relief over a distance of at least 6.4m (1/4") from the edge of the fit.
A: It is important that the stress relief grooves be at least 12.5 mm (1/2") deep and that the thickness of the lip at the edge be held at 1.6mm (1/16"). The side of the stress relief groove adjacent to the shaft should have an easy slope, as shown, to provide effective relief over a distance of at least 6.4m (1/4") from the edge of the fit.
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