Oil Mist Detection

What is Oil Mist? Casualties and Incidents Classification Societies
Crankcase explosions have been the cause of several and even fatal incidents in the past.

A crankcase explosion can cause:

  • Damage to several parts of the engine (crankshaft, main bearing, piston, and others)
  • Loss of steering capability of the ship
  • Loss of production electricity (high risk for ships; financial losses for powerplants)
  • Loss of profit due to business interruption
  • Employer’s liability
  • Loss of vehicle use
  • Damage to the company's image.
  • Loss of lives

Some known cases of cranckase explosions:

1) In September 1947, the catastrophic crankcase explosion onboard the “ Reina del Pacifico” was the start of the development of oil mist detectors.
Cause: The primary explosion was caused by the overheating of No.2 piston of the port outer engine. The other three explosions were due to the inflammable content of the crankcases being ignited
Consequences: 28 deaths

2) Engine: B&W 8 UEC 75 LLII built under license by Mitsubishi Heavy Industries in Japan
Cause: A failure on the nº1 unit, piston crown, allowed direct communication of the combustion chamber with the crankcase. Hot combustion gases created and ignited a flammable oil mist mixture from the oil droplets present in the crankcase, causing a primary crankcase explosion. The crankcase explosion relief valves failed to re-seat properly, allowing air back inside the engine to give conditions suitable for a second explosion to take place and for ignition at every firing cycle until fuel was removed from the injection system.
Consequences: Physical and heat damage in the engine room was significant. The vessel’s main engine was disabled.

3) Engine: Engine Sulzer ZA40
Cause: Lack of lubrication caused the connecting rod and lower skirt to break free, smashing the bottom of the liner and engine frame.
Consequences: The damage to the frame was so extensive that the engine had to be replaced.

4) Engine: Bergen V12
Causes: Incorrectly tightened split sprocket after an overhaul started fretting causing micro-seizures, which led to a fracture and propagated causing the crankshaft to shear. The crank was so misaligned that the inner and outer elements of the clutch meshed, burning out the clutch pads/rubber support rings, ledding to metal /metal contact causing a small fire.
Consequences: Crankshaft, bearings, damages liners, running gear and clutch had to be repaired.