| Functional
Differences between RCM and PMO
RCM and PMO are completely different
products with the same aim; to define the maintenance
requirements of physical assets. Asset managers should
be aware however, they have been designed for use in
completely different situations. RCM was designed to
develop the initial maintenance program during the
design stages of the asset life cycle (Moubray
1997) whereas PMO has been designed for use where
the asset is in use.
As a result, PMO is a method of
review whereas RCM is a process of establishment.
Whilst arriving at the same maintenance program, PMO
is far more efficient and flexible in analysis than
RCM where there is a reasonably good maintenance
program in place and where there is some experience
with the plant operation and failure characteristics.
Methodology
differences between RCM and PMO
The central difference
between RCM and PMO is the way in which failure modes
are generated.
- RCM generates
a list of failure modes from a rigorous assessment
of all functions, a consideration of all
functional failures and then an assessment of each
of the failure modes that relate to each
functional failure. RCM seeks to analyze every
failure mode on every piece of equipment within
the system being analyzed.
- PMO
generates a list of failure modes from the current
maintenance program, an assessment of known
failures and by scrutiny of technical
documentation - primarily Piping and
Instrumentation Diagrams (P&IDs).
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Figure
1
Comparisons of PMO and RCM
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The
differences in the two approaches mean that PMO deals
with significantly less failure modes than RCM and
arrives at the failure modes in a far quicker time
frame. Experience
in the US Nuclear Power Industry was that over a large
number of analyses, PMO was on average six
times faster than RCM¹.
The methodological differences between RCM and
PMO are illustrated at Figure 1.
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¹ Johnson
1995 |
