Chemical Technology February 2015

Petrochemicals

PLANT MAINTENANCE, HEALTH, SAFETY AND QUALITY

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 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!

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Chemical Technology • February 2015