Miscelleneous

What is Crankcase Explosion and reasons/causes of its occurance? What actions you will take if oil mist has occurred?

  • Oil Mist in Crankcase

In order to ensure a reliable, and quick warning of oil mist formation in the crankcase, constant monitoring is obtained with an “Oil Mist Detector”, which samples air from each crankcase compartment.

The detector will give alarm and slow-down, at a mist concentration which is only a fraction of the lower explosion limit, LEL, to gain time to stop the engine before ignition of the oil mist can take place.

Measures to be taken when Oil Mist has occurred

1) Reduce speed/pitch to slow-down level, if not already carried out automatically.

2) Ask the bridge for permission to stop.

3) When the engine STOP order is received:

  • stop the engine
  • close the fuel oil supply.

4) Switch-off the auxiliary blowers and engine room ventilation.

5) Open the skylight(s) and/or “Stores hatch’.

6) Leave the engine room.

7) Lock the casing doors and keep away from them.

8) Prepare the fire-fighting equipment.

Do not open the crankcase until at least 30 minutes after stopping the engine. When opening up, keep clear of possible spurts of flame. Do not use naked lights and do not Smoke.

9) Stop the circulating oil pump. Take off/open all the lowermost doors on one side of the crankcase. Cut off the starting air, and engage the turning gear.

10) Locate the “hot spot”. Use powerful lamps from the start.

Feel over, by hand or with a “thermo feel”, all the sliding surfaces (bearings, thrust bearing, piston rods, stuffing boxes, Crossheads, telescopic pipes, chains, vibration dampers, moment compensators, etc.). See also point 14. Look for Squeezed-out bearing metal, and discolouration caused by heat (blistered paint, burnt oil, oxidized steel). Keep possible bearing metal found at bottom of oil tray for later analyzing.

11) Prevent further “hot spots” by prefer ably making a permanent repair. In case of bearing running hot,

About the author

Anand Gautam

Anand Gautam is a marine engineer, Graduated from M.E.R.I. Mumbai. He likes to sail onboard ship and is one who is passionate about his job. He loves to share his knowledge, information, and ideas to everyone in a simplified way just for his satisfaction.

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