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Petrochemicals
Chemical Technology • February 2015
strategy to adopt is not to allow failure modes into the equip-
ment from the start. Such strategies require that you put
in place management controls and quality standards that
must be followed to detect, control and stop the introduction
of errors and defects into the equipment.
For example, a wise strategy at the design stage is to
look for every failure mode possible and remove it whilst it is
still on the drawing board. You take each part of the equip-
ment, assembly by assembly, component by component
and list its possible defects and errors and then introduce
strategies and plans to address every one of those failure
paths in the design.
A spreadsheet can be developed of all component and
assembly failure modes and this becomes a checksheet to
assess all future equipment purchases and designs. It also
identifies where you should use preventative and planned
replacement maintenance strategies. Some people call
this RCM (Reliability Centered Maintenance). But I call it
just plain common sense!
Maintenance is used to address the effects of the contin-
ually growing number of defects. You will often hear people
say "well add another PM into the system", hoping that it
will prevent the problem in future. But all they have done
is add more cost and resources requirements into the pro-
duction costs! More maintenance is not the answer; it only
adds more expense without benefit of defect elimination.
Maintenance can only act to ‘drain away’ the impact
of defects. It hides and masks their effect. But it cannot
remove them because maintenance only replaces like-for-
like. The original defect remains.
You now have an equipment defect model that explains
why there is somuch crisis and ‘fire-fighting’ by maintenance
crews. Doing maintenance does not fix problems; it can only
PLANT MAINTENANCE, HEALTH,
SAFETY AND QUALITY
Figure 1 highlights where most failure-casing defects and
errors come from and explains that eventually you will have so
many problems in your operation that your bucket overflows
and you drown in strife!