1) Equipment Criticality PARTIAL COST Column, 2) Risk Matrix Validity for Frequent Failure Events
MikeS
I am on the 2nd activity of the maintenance planning training course
Module 1 involving equipment criticality. Please, I would like you to
1) explain further the PARTIAL COST Column, and also I would like to
know 2) if the RISK MATRIX still applies when the equipment's MTBF
is for example 1 in 6 months and less?
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Hello,
1) The Partial Loss column in the Equipment Criticality Table is used
to show the total business-wide cost (DAFT Cost) of a sub-system or
sub-assembly failure.
For example the Table shows the cost from a likely worst case failure
event of a diesel engine’s fuel system by fuel blockage. One of the
presumptions we make is that a fuel blockage will not destroy the
whole engine.
The $25,000 total business-wide cost to rectify a major fuel system
blockage is much less than the cost of replacing the failure of a
whole engine for $500,000. We identify the DAFT cost of total engine
failure separate from the DAFT cost of the fuel sub-system failure to
see the impact of the sub-system loss on the asset’s total risk.
Another example—the partial loss cost of a crank/piston failure shown
in the Table is half the DAFT cost of an event that results in losing
the whole diesel engine. The presumption made in the Table is that
only the engine block is damaged should there be a crank/piston
failure event. A likely worst case crank/piston failure would
destroy the engine block and that means it has to be replaced and the
engine rebuilt. It s a terribly expensive $250,000 failure compared
to a $25,000 fuel system failure.
The risk to the business of a crank/piston failure is much higher than
the risk from a fuel system failure. Given the choice you do not want
crank/piston failures because they lose a lot of money. Their high
risk to the business justifies coming up with good solutions to
prevent engine blocks from failing in the first place.
To reduce the risk you need to select suitable risk reduction
activities. You then use the risk matrix to prove that those risk
mitigation activities will substantially lower the risk . If you
cannot clearly see the risk fall on the risk matrix then the
activities you chose need to be replaced with more effective choices.
2) The Risk Matrix always applies in every situation. Risk is always
around us and we can show it on a Risk Matrix. A 1 in 6 month
frequency and more often for an event implies CERTAIN failure.
The frequency of a failure event comes from the history of its
occurrence in your operation. A failure that happens once every six
months on average is certain to happen again shortly, unless you do
something that prevents it from repeating so often.
Even a failure event that occurs once in a year would be classed as
CERTAIN, since it will surely happen again in your operation in the
foreseeable future.
If you have more questions please ask. I am happy to answer them.
Best regards,
Mike