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Fixed vs. Floating Schedule PMs

  • 1.  Fixed vs. Floating Schedule PMs

    Posted 04-23-2021 02:51 PM

    Hi folks -

    The topic is Fixed vs. Floating schedule PMs!!  I have a pretty good idea how each schedule type works however, I am interested in learning how your organization/you have used these PM schedule types.

    Are your PMs predominately Fixed or Floating schedule? What % of each do you have?

    If you are part of a more mature maintenance organization that realizes the importance of completing PMs by their due date and monitors them with KPIs is there a down side to most PMs being Fixed schedule?

    Say 95% of your PMs were Fixed schedule and the outlying 5% were set up as Floating schedule. The Floating schedule PMs would only be PMs that could not be executed without an equipment outage. Those PM would be set up to generate WOs in a status of HOLDSD (hold for shut down). Folks would be able to find these WOs when needed and the scheduler knows not to schedule them by the assigned status.

    How does your organization use Fixed vs. Floating schedule PMs? Is there set criteria or a guide that defines which to use based on the work?

    Thanks in advance, I am excited to read and learn from your experience!!



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    Jason Weis
    PMP, CMRP, CRL
    Trainer, Pennsylvania
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  • 2.  RE: Fixed vs. Floating Schedule PMs

    Posted 04-23-2021 06:01 PM
    Hi, Jason --

    Floating schedule PMs are a lifesaver for predictive and condition-based maintenance.   If you have enough historical data you may have a rough idea when you will need to intervene, but the precise timing is dictated by the monitoring data. 

    The frequency of the fixed schedule PMs is dictated by your risk assessment and/or the requirements for protecting the manufacturer's warranty for the equipment (and/or a wide variety of other considerations).  If a shutdown is required, you have to get with the operations folks and schedule the shutdown.   Of course if there's an unplanned shutdown before the PMs are due you can consider taking advantage of that, but if you've put your time and effort into developing PM frequencies they should all be fixed schedule. 

    I sincerely hope this helps.

    ------------------------------
    Daniel Corman
    Houston TX
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  • 3.  RE: Fixed vs. Floating Schedule PMs

    Posted 04-23-2021 07:39 PM
    Hi Daniel - your response certainly helps, I appreciate you taking the time to post! I agree a majority of the PMs (not talking about PdM or condition based maintenance) if not all with set frequencies should be Fixed schedule. The HOLDSD WOs generated from PMs should be floating schedule. This way PM WOs will not continue to generate WOs when we know thy cannot be executed until the equipment can be shut down or there is an outage. Once the HOLDSD PM is completed the PM can then generate the next PM WO based on the frequency based on the finish date of the previous PM WO.

    Looking forward to hearing some others feedback!!

    ------------------------------
    Jason Weis PMP CMRP CRL
    Project Manager
    Monroe Energy
    Trainer, Pennsylvania
    ------------------------------



  • 4.  RE: Fixed vs. Floating Schedule PMs

    Posted 04-24-2021 11:27 AM
    I think part of the answer to this question depends how you define PM's.  Some include corrective work in their PM definition.  For example, you do condition monitoring on an AC motor and find that a bearing is going bad and change out the motor at some point.  I my book, the change out is not a PM, it is  (hopefully) a "planned and scheduled corrective work".

    The reason not to include corrective work in PM is that there is an overlap with planned corrective, scheduled corrective, and planned and scheduled corrective.  If you do, you can never get the KPI's right, and you will confuse the organization.  You see how the above changes the answer quite a bit, and some include the repairs into PM's.

    But, if PM's are inspection (including synonyms such as condition monitoring PdM) and fixed time, or fixed meter replacements only.  You SHOULD have fixed PMs. Like you said the organization SHOULD do the PM's in time, but.... they can become a mess if you don't follow the schedule.  For inspection routes (including look, listen feel, small, IR, VA etc), I think a fixed schedule for performing the inspections are reasonable to get done.  The corrective work coming out from those routes are a technical decision and you should plan and schedule that work as need be.  

    For fixed time shutdown work... example, re-grease, change gaskets, align grid and gear couplings.  I think they need to be work balanced over the year so you have the same work load in each shutdown.  some of that work can be re-scheduled since they are not suber time sensitive +/- 3 months is usually OK.

    From a philosophical and culture change stand point.  By having "floating PM's" you set the tone for the company.... PM's is not THAT important, just a little important.  Not enough people?  You can always hire contractors and do overtime if you felt PM's were important (don't hire contractors for PM's , but for the other work).  It is a question of short term or long term gains.  

    So, if I'm on my soapbox, I would say push for fixed time PM's, make sure they are done!!!  Byt, being practical, i agree, keep some PM's floating until you get your arms around them, then move to fixed.  For example, we do this with starting inspections, if someone inspect something 5 times and things are not fixed, they stop doing them, so perhaps good to start floating, then with 80% are fixed, do the inspection again.


    ------------------------------
    Torbjorn Idhammar
    President & CEO
    IDCON, Inc.
    http://www.idcon.com
    Raleigh NC
    ------------------------------



  • 5.  RE: Fixed vs. Floating Schedule PMs

    Posted 04-24-2021 12:37 PM
    Thanks for responding Torbjorn. Let's stick with SMRP's definition of PM. 

    Preventive Maintenance (PM)
    Actions performed on a time- or machine-run-based schedule
    that detect, preclude or mitigate degradation of a component or
    system with the aim of sustaining or extending its useful life
    through controlling degradation to an acceptable level.

    I agree with you that making PMs fixed schedule shows the organization understands the importance / benefits of completing the PMs on time. They will need to dedicate the proper resources to complete them on time. Forecasting resources required to complete the work in advance can help management determine the proper level of resources to keep PMs on schedule. 

    Jason

    ------------------------------
    Jason Weis PMP CMRP CRL
    Project Manager
    Monroe Energy
    Trainer, Pennsylvania
    ------------------------------



  • 6.  RE: Fixed vs. Floating Schedule PMs

    Posted 04-26-2021 10:15 AM
    Hello All - Also to consider how most CMMS' handle the PM generations: Fixed PMs keep generating WOs on your schedule. If a PM is missed you will still get a new one when the next is due. Floating PMs will not generate a next PM until​ the current open WO is completed (Once completed reschedules the next PM due). Be careful with floating PMs - if missed or not completed on time then the frequency between services can go longer than the desired PMs frequency.

    ------------------------------
    Mike Pytlinski, PE, CRL
    Senior Engineer
    Metropolitan Water District of Southern California
    La Verne CA
    ------------------------------



  • 7.  RE: Fixed vs. Floating Schedule PMs

    Posted 04-26-2021 10:57 AM
    Thanks for the information Mike! 

    So assuming we understand the difference between the two types of PM schedule types, I am interested to hear about what percentage of each type are active in your/everyone's system?

    Ill start - If we make some proposed changes, about 97% of our PMs will be fixed schedule and the remaining 3% or so will be floating.

    Jason


    ------------------------------
    Jason Weis PMP CMRP CRL
    Project Manager
    Monroe Energy
    Trainer, Pennsylvania
    ------------------------------



  • 8.  RE: Fixed vs. Floating Schedule PMs

    Posted 04-26-2021 11:14 AM
    Hello All - We currently have 96% set as fixed and 4% as floating. We stick mostly to fixed as to not miss upcoming maintenance if a WO is not completed or closed on time. Our floating PMs are special PMs closely monitored to ensure they are completed & closed on time.​

    ------------------------------
    Mike Pytlinski, PE, CRL
    Senior Engineer
    Metropolitan Water District of Southern California
    La Verne CA
    ------------------------------



  • 9.  RE: Fixed vs. Floating Schedule PMs

    Posted 04-26-2021 12:15 PM
    Agree with many others on PM fixed and priorities. 

    Really understanding the whole PM philosophy and applied RCM, there is no point in having a floating PM.  PM means that we have a failure mode that we need to manage by a certain task at a said frequency.  If you have a floating PM then your task or your PM frequency may not be correct.

    RCM targets certain failure modes with certain P-F intervals and the PM frequency is set according to that information in order to manage asset reliability.  

    When I see floating PMs it is usually due to several reasons. 
    1. There are too many PMs in system (wrong ones, redundant, or unnecessary PMs). 
    2. Not enough resources to execute good PMs.
    3. Lack of commitment by management for PM program.

    There are many cases for allowing PMs to slide in order to fit downtime schedules but I don't call those floating PMs.  That is fitting your PMs into the business model for your industry.  I'm not sure any 24/7 industry will allow a rigid shutdown to execute a fixed time PM just because it is due.  They need to fit within an existing scheduled down.

    Great topic and discussion.

    ------------------------------
    Randy Riddell, CMRP, PSAP, CLS
    Reliability Manager
    Essity
    Cherokee AL
    ------------------------------



  • 10.  RE: Fixed vs. Floating Schedule PMs

    Posted 04-26-2021 12:39 PM
    Awesome Randy!

    And you nailed the PMs that need to fit into the production schedule part by the way. Those are the 3 or 4% Floating schedule PMs that we will get when the opportunity presents itself. It will either happen during a scheduled SD or an unscheduled outage. The frequency will still be set to when we would like to work it however, the work may need to wait until Ops/Scheduling and Optimization determine the best time to come down. 

    The lead times can be increased and alert lead times (if your cmms has this functionality) can also be adjusted to give the opportunity/option to generate the PM WO before the PM would be normally be generated. This way the business has more opportunities to complete these hard to schedule PMs due to the operation. 

    Jason

    ------------------------------
    Jason Weis PMP CMRP CRL
    Project Manager
    Monroe Energy
    Trainer, Pennsylvania
    ------------------------------



  • 11.  RE: Fixed vs. Floating Schedule PMs

    Posted 10-04-2021 10:04 AM
    Hi Jason,

    Thanks for posting this exciting topic.

    I am in the middle of a Maintenance Build project in my company, and this topic came up on the table.
    After reading all the other members' interventions, I guess the biggest concern is a helpful guide (API or Any different Standard) to help settle PMs properly. Some companies flag PMs as Floating when their Equipment isn't regulatory compliance in CMMS. In some other cases, it's based on the condition for work assigned to the kit.

    Does any of the existing standards talk about the proper set-up of PMs?



    ------------------------------
    Daniel Dos Santos
    Maintenance Planning Specialist
    Luanda
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  • 12.  RE: Fixed vs. Floating Schedule PMs

    Posted 10-05-2021 06:50 AM
    Hi Daniel,

    We decided to make all of our PMs fixed except for the ones that required a shutdown, those will be floating with a greater lead time.  We could not find any existing standards on this topic.

    ------------------------------
    Jason Weis PMP CMRP CRL
    Project Manager
    Trainer, Pennsylvania
    ------------------------------



  • 13.  RE: Fixed vs. Floating Schedule PMs

    Posted 10-06-2021 11:48 PM
    Process safety and statutory PMs should always be fixed. Unfortunately, reliability PMs tended towards KPI driven behaviour that favour floating. RCM perspective drives fixed schedules from studying the P-F curve logic. Personally I would push for fixed schedules based on P-F (ie. mtbf). Then drive the organization to have the process of deferrals which requires risk assessments and impose the necessary mitigations example more frequent vibration monitoring. Fixed schedules PM should also apply to unit shutdowns and apply the deferrals. This will help drive the risk assessments for moving shutdown dates and surface those PMs for consideration.

    ---------------------------------
    Tee Yeow Hum
    Reliability Manager
    Shell
    Singapore
    ---------------------------------