Fatal
crankcase explosion A superintendent has been killed by
a crankcase explosion in a MAN B&W low-speed engine on a
Korean test bed. The accident happened when a bearing in
the chaincase overheated, causing a build-up of oil mist
while the engine was undergoing shoptrials.
The Motor Ship understands that the oil mist detectors were
not wired into the test bed's alarm system. Following the
incident MAN B&W has re-issued advice on the testing procedure,
stressing that oil mist detectors must be connected before
the initial start-up.
It has also upgraded the instruction saying that with immediate
effect the oil mist detectors must be connected to the automatic
shut down system on the testbed rather than to the alarm
system. "If anything is going to go wrong it is most likely
to happen in the shop trial - that's why the trial is run,"
says Mr. Jakobsen, manager of new design at MAN B&W.
Wärtsilä NSD has not issued specific instructions on the
connection of oil mist detectors during shoptrials, saying
it expects its licensees to take all precautions to protect
its workers. However, it is reviewing this policy in the
light of this accident.
Christian Lutsen of AP Moller, whose Sovereign Maersk suffered
a crankcase explosion, says he feels it would be smart to
have a thicker white metal layer in the bearings. In the
event of a main bearing failing, as happened in the 12K90
engine aboard Sovereign Maersk, there would not be metal-to-metal
contact.
Mr. Jakobsen from MAN B&W says the company would not revert
to thicker bearings as this would lower the load carrying
capabilities and not solve the problem. If the failed bearing
had a thicker layer then it would wear down the neighbouring
bearings, and within a few hours the same metal-to-metal
contact occur, he argues.
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Left
to right: large, small and no shield - demostrates
why MAN B&W does not recommend shields on crankcase
valves.
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