Torbjörn Idhammar of IDCON reveals a smarter approach to preventive maintenance
When we visit plants we are often asked, “What are the current best practices for preventive maintenance (PM)?” We usually answer that we define preventive maintenance using 124 key elements in our PM Focused Assessment. We also point out, to some people’s dismay, that there is no single silver bullet for improving PM, but rather many combined efforts are required to yield results.
Below are examples of some of these questions to see how your plant measures up (BP is the Best Practices Example).
Do you have a definition for preventive maintenance?
Interview test: Ask people in maintenance and operations to define what is included in preventive maintenance.
BP example: We have a definition of preventive maintenance that is documented, understood, and well communicated across our plant.
Having a definition of preventive maintenance is important for good communication in meetings, improvement efforts, and training seminars. For example, are detailed cleaning, balancing, and alignment part of preventive maintenance? Is operator inspection part of PM? Are operating practices part of PM?
IDCON has attended meetings or interviews where we are told a plant is continuously working on improving preventive maintenance. When we ask for the plant’s definition of PM, we notice that there are as many definitions of PM as there are people. How can you expect to improve PM if you are not clear on what PM really is? IDCON defines PM as essential care and condition monitoring (PM/ECCM) as shown in Fig. 1. You are welcome to use this definition in your organisation.
Do you know how satisfactory PM is done today?
Test: Ask the plant manager, maintenance manager, and operations manager for the PM improvement plan. If there is one, are timelines specific? For example: “Lubrication storage improvement complete by September 2016.”
BP: Plant management is aware of strengths and weaknesses of the PM program. The plant therefore has specific plans and timelines in place for improvement actions.
First defining what PM is and then educating and training people in the current state of their actual PM performance lay the groundwork for improvement.
Do you have an alignment standard, and is it followed?
Test: Ask for an alignment standard and check quality of standard. Go look at equipment for signs of good or poor alignment.
BP: There is a well-documented alignment standard. More importantly, the standard is followed. There is a well-defined alignment standard explaining how to set up, clean, check for pipe strain, check for soft foot, etc.
In a world-class reliability and maintenance organisation, all alignments are done to 0.002in. (0.05mm) for equipment running below 3600rpm and 0.001in. (0.025mm) for equipment running above 3600rpm.
Take a tour of your plant. If alignment is done well there are jacking bolts (push bolts) installed on all motors, gears, and other equipment of significance. Bases and foundations are in good condition and no more than four shims are used under the motor feet (Fig. 2). Overall vibration level is low in the plant (0.1 in./sec unfiltered average). As a tracking indicator, see if alignment records are kept for each alignment job.
Do you have a lubrication standard, and it is followed?
Test: The standard should include storage, handling, filtering, and cleanliness of lubricants. Visually check cleanliness of storage areas and handling.
BP: There is a well-documented lubrication standard. More importantly, the standard is followed.
The cleanliness standard for each piece of equipment should match the clearances in the equipment’s lubricated surfaces. For example, a hydraulic unit may need to be filtered down to 3 microns (200 beta) and a gearbox to 12 microns (75 beta).
To reach the right cleanliness levels of lubricants, oil and grease have to be stored, handled, and filtered correctly. Few people know that new oil usually is delivered at around 40 microns cleanliness level, which means that oil going into equipment with fine clearances should be filtered.
Are inspections (condition monitoring) done where it is cost effective to do so?
Test: Go through inspection lists, check for level of detail, and make sure the route is actually completed.
BP: There are inspection routes for all mechanical, electrical, and instrumentation equipment (where it is cost effective to have inspections).
In a top-notch plant, inspections are documented and completed according to schedule. The plant is using an inspection list or, even better, a handheld computer. The list or handheld computer describes exactly what to do for each inspection. The inspections are a combination of measuring condition and subjective (look, listen, feel, smell) inspections.
Most inspections are completed while equipment is operating because we do not want to waste valuable shutdown/offline time on inspections that could be done on the run. Inspections can usually be done better when equipment is operating. For example, a pump cannot really be inspected well when it is down since there are no vibration, no operating pressures, and no seal water flow.
To see if your plant is performing according to world-class reliability and maintenance standards, take an inspection list, or handheld computer (if you do not have inspection lists, it is time to develop them), and walk the route. For example, check the following:
* Do we have condition monitoring routes covering all necessary inspections?
* Do we use simple inspection tools such as a stroboscope, infrared thermometer, vibration pen, industrial stethoscope, bright flashlights (500,000 candela), and inspection mirrors?
* Can we inspect couplings, belts, and chains on the run, or do guards make it impossible (Fig. 3)?
* Are inspections being done? Are oil glasses clean enough to see oil levels, are base bolts clean enough to check tightness, etc.?
* Are people educated and trained in basic inspection techniques?
Is detailed cleaning of equipment done well?
Test: Take a walk in your plant and visually check the cleanliness and condition of the equipment.
BP: Detailed cleaning of equipment is done consistently. Dirty areas are redesigned in order to protect equipment from contamination.
Detailed cleaning can be checked easily. For example, a clean hydraulic unit can be inspected for leaks in about 10 seconds by taking a quick look at the pan underneath the unit (Fig. 4). A dirty hydraulic unit would take 20-30 min to check for leaks.
Is an ultrasonic or vibration monitor used when greasing bearings?
Test: Check lubricator’s equipment.
BP: Vibration or ultrasonic levels (or other method) are checked while greasing in order to apply the correct amount of grease.
Greasing is done by measuring ultrasonic or vibration levels while applying grease to the bearing. It is almost impossible to know how much grease is applied to a bearing without a measurement. The measurement tools indicate to us when the grease hits the bearings and monitor the vibration or ultrasonic levels as grease is squeezed into the bearing. Over and under greasing can be avoided by using the right tools. An alternate method is to use a volume meter, assuming the required grease volume for the bearing is known.
The questions above are a small sample of the 124 points IDCON uses to evaluate a plant’s PM performance, these example tests and best practices demonstrate the methodology by which one can build a system for discussing performance levels. I invite you to contact me if you have questions about evaluating your PM program at firstname.lastname@example.org
Torbjorn Idhammar is president of IDCON, a highly specialised management consultant firm in the field of reliability and maintenance management. The company's mission is to improve overall reliability and minimise total production cost for its clients in the power industry.