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Recently there has been some debate amongst my peers at work on whether or not time-based Intrusive inspections of static equipment (primarily shell and tube HX) should be assigned a 'Work Type' of 'Condition Monitoring/Predictive' or 'Preventative' maintenance.  Historically I have always considered this type of inspection to fall under the 'preventative' category, primarily as it requires an equipment outage to perform the work and they are a time-based activity.  There are elements of Condition Monitoring in the tasks as we would collect tube thickness measurements and trend them over time to determine an optimum repair/replacement schedule and oftentimes the equipment will be closed back up without any specific 'restorative' task performed beyond the cleaning required to do the inspection.

I am particularly interested in the classification as it relates to the Best in Class targets for Work Types as published in the SMRP Best Practices.  If we were to include these inspections as Condition Monitoring it will drastically change our relative percentages for CM vs PM.  Most references I can find would support my current opinion, but I have not found any that categorically state which way these inspections should be classified.

Would be very interested to hear how others classify this work.

Thanks!

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Mark Siford, P.Eng., CMRP
Condition Monitoring Manager
Nova Chemicals Corporation
Joffre, AB
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Mark,
A part of any comprehensive PM program is called "Fixed Time Maintenance (FTM)". FTM consists of work that is not route-related. That is, this work is normally scheduled in the CMMS as a stand-alone task that exists only to execute a single overall task such as a Planned Component Replacement or a Condition Monitoring task such as the inspection task you have described. 

I can't say that SMRP has a standard description somewhere that agrees with this but common sense says that this is the right way to classify this type of work. But then, each organization has the latitude to classify their work as they wish.

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Terry Taylor
Taylor Reliability Consulting
St. Johns, Florida
ttaylor@taylorreliability.org
919-537-2812
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Hello, Mark --

I agree with your assessment that inspecting the equipment on a periodic basis should be categorized as preventive maintenance.   If, during the inspection, you're measuring the tube thickness and you use that trend to predict the time to failure, then replacing them before they become dangerously thin would be predictive/condition monitoring. 

Similarly if your inspector carries a handheld vibration detector on preventive maintenance rounds, replacing a pump or motor before the bearings fail would be predictive/condition monitoring, but measuring the vibration is part of the regular preventive maintenance. 

I sincerely hope this helps.

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Daniel K Corman, CMRP
Houston, Texas, USA
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Mark,

I would suggest an approach that is slightly less philosophical and look at the practical application of calling it a PM or CM. If you call it a PM or CM, do you take different action at the plant? What does it mean for you to have a higher percentage of CM vs PM? Do PMs or CMs get more prioritization in the work scheduling process?

My two cents from a philosophical standpoint is that fixed equipment thickness monitoring gets overlooked as a CM since it doesn't involve the technologies we typically think of when talking about CM (vibration, ultrasound, etc), but you are monitoring the condition of the asset using data. With that in mind, I'd call it a CM.



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Neil Burrows
Reliability Manager
J.R. Simplot Company
Pocatello ID
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Hi Mark,

My thoughts - I would always classify static inspections like these as PMs. In my simplistic view, anything that is done before a functional failure is a Pm, anything after a functional failure is a CM. Then within PMs, you can break it down into time-based maintenance, condition-based maintenance, risk-based maintenance etc.

If this inspection is done on a fixed interval i would classify it as a CBM task, if you run RBI and adjust scope and frequencies of inspections based on your findings I would classify it as RBM (Risk Based Maintenance).

I would be very, very careful with using best-in-class targets for work types, companies all use different definitions, and therefore using these best-in-class values as targets for your company can be very misleading. Instead, I would agree on a set of definitions you use internally and trend your own ratios and see if they are heading in the right direction.

PS if you are interested in a more detail breakdown of maintenance types I wrote an article about it a while ago: https://roadtoreliability.com/types-of-maintenance/

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Erik Hupje
http://www.roadtoreliability.com
https://www.linkedin.com/in/erikhupje/
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