Answer EKM Question 6

Q6. Discuss the precautions that can be taken to minimize the possibility of a diesel engine c/c explosion and the transmission of dangerous flame into the machinery spaces,

A. By design & equipment

B. By operating personnel.
Answer: By design and equipment

• Bearing material should be chosen that offer minimum friction and generation of heat. The material should have sufficient strength to carry the maximum expected load. the material should not readily deteriorate in service.
• Shaft or journal and bearing dimensions should be adequate in order to ensure that the permissible specific load is not exceeded.
• It should be ensured that adequate lubricating oil is delivered to the loaded area to assist the formation of hydraulic oil film. Oil passages, grooves, bore relief and tangential run out of the bearings should be provided as necessary.
• the lubricating oil pump, filter, cooler and pipe line system should be designed properly so that sufficient oil at correct pressure and temperature is delivered to all bearings, gear, chain drive and other rubbing parts.
• Arrangement should be provided for efficient purification of the lubricating oil.
• Only good quality oil should be chosen as recommended by engine makers.
• Thermometers should be provided at strategic points to monitor temperature of the lubricating oil in the supply and return lines.
• Bearing temperature indications and alarms should be provided.
• Oil mist detectors should be installed.
• crankcase door explosion relief valves should be installed as per classification regulations.

By Operating personnel

• Good house keeping- pump, cooler, filter maintained in good condition, oil sent regularly for analysis and remedial action taken as necessary based on the analysis report.
• Use only good quality lubricating oil as recommended by engine builders.
• Maintain adequate level of oil in the drain tank.
• Continue to run the lubricating oil pump for at least 30 minutes longer after stopping the engine.
• Lubricating oil purifiers should be run at all times when the ME is running and even in port.
• Lubricating oil temperature should not be allowed to extend to exceed the recommended limit.
• Planned maintenance and regular inspection of crankcase.
• Any sign of overheating e.g. high lubricating oil temperature, unusual warming up of crankcase door noticed when feeling by hand should be investigated and set right at once after slowing down or stopping the engine as necessary.
• Ensure that the oily mist detector, temperature monitoring and alarm system works properly.
• Check bearing clearances and crankshaft deflection at scheduled intervals. Any abnormality should be investigated and set right as soon as possible.
• Hot feel any bearing when renewed or worked upon. This is done by starting the engine and stopping (a) after 15 to 30 minutes. (b) after one hour and (c) when full load has been reached and then feeling the bearing by hand and comparing its temperature with other bearings to check that temperature of the affected bearing is not too high.