http://blogs.reliableplant.com/1182/prioritize-work-orders/ Blogs from ReliablePlant.com Wed, 16 May 2012 14:04:56 +0000 http://wordpress.org/?v=2.6.3 http://blogs.reliableplant.com/1182/prioritize-work-orders/#comment-19096 Mark D Wed, 16 Jun 2010 15:13:35 +0000 http://blogs.reliableplant.com/?p=1182#comment-19096 Another Engineer and I have been toying with a new criticality/prioritization scheme. Basically, we are going to propose a 3 digit crticality number to be used for prioritization purposes. The number although appearing to be a single number is actually 3 separate pieces of information. The first digit represents severity of consequence of the typical or most anticipated failure. The second represents inherent redundancy per the reliability strategy (inline spare, stocked spare, no spare). The third number is the average P-F Interval or MTBF expected for the equipment. This last one is tricky. I don't like probability or liklihood of failure because they don't speak to timing unless you can do Weibull analysis or similar. However, based on FMEAs and MTTF/MTBF data, is more useful and more readily available from a CMMS. So this last digit helps gauge time to repair. I don't think emergency situations are the challenge...they are readily assessed and addressed. It's all the "we don't have to fix it right away" stuff that eventually leaves something behind to be forgotten. Then we can compare any prioritization number to the age of the work order (that is an easy report). Also, the order of the number is key--Severity is the biggest determiner, Redundancy next, and P-F interval third. If we use a simple range of 1-5 for each, a criticality number would look like 555 for the most extremely urgent case vs 111 for the least urgent. However, one could now judge a 523 as more critical equipment than a 345, AND they can tell why at a glance. Does this mean that strict rules apply? No. Could there be a reason that the 345 goes ahead the 523 in the maintenance schedule? Sure. But trying to keep all those reasons sorted out has got to be tough on the one individual prioritizing. We believe this number also still works mathematically/statistically in terms of sorting, histograms, etc. Over time, if engineering or process changes effect the rankings of any of the three numbers, then the criticality would simply be updated. Lots of information here. Thoughts and comments? Another Engineer and I have been toying with a new criticality/prioritization scheme. Basically, we are going to propose a 3 digit crticality number to be used for prioritization purposes. The number although appearing to be a single number is actually 3 separate pieces of information. The first digit represents severity of consequence of the typical or most anticipated failure. The second represents inherent redundancy per the reliability strategy (inline spare, stocked spare, no spare). The third number is the average P-F Interval or MTBF expected for the equipment. This last one is tricky. I don’t like probability or liklihood of failure because they don’t speak to timing unless you can do Weibull analysis or similar. However, based on FMEAs and MTTF/MTBF data, is more useful and more readily available from a CMMS. So this last digit helps gauge time to repair. I don’t think emergency situations are the challenge…they are readily assessed and addressed. It’s all the “we don’t have to fix it right away” stuff that eventually leaves something behind to be forgotten. Then we can compare any prioritization number to the age of the work order (that is an easy report). Also, the order of the number is key–Severity is the biggest determiner, Redundancy next, and P-F interval third. If we use a simple range of 1-5 for each, a criticality number would look like 555 for the most extremely urgent case vs 111 for the least urgent. However, one could now judge a 523 as more critical equipment than a 345, AND they can tell why at a glance. Does this mean that strict rules apply? No. Could there be a reason that the 345 goes ahead the 523 in the maintenance schedule? Sure. But trying to keep all those reasons sorted out has got to be tough on the one individual prioritizing. We believe this number also still works mathematically/statistically in terms of sorting, histograms, etc. Over time, if engineering or process changes effect the rankings of any of the three numbers, then the criticality would simply be updated. Lots of information here. Thoughts and comments?

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