It's like eating an elephant
you've got to do it one bite at a time.
by Michael V. Brown
Which came first, the PM program or the emergencies? I once casually asked an 85-year-old woman how she kept her large old farm house so clean. Expecting a simple "Thanks" for the compliment, I was surprised when she began to explain her method. "First you take a broom and sweep the kitchen," she said, and then continued to describe the steps in keeping a house clean. The simple but effective view she took to housekeeping made me think about a common obstacle to preventive maintenance cited by maintenance managers. Too many managers I meet today state that there is no time to perform preventive maintenance because a large part of their workforce is dedicated to emergency repairs. Paradoxically, these managers usually realize that if they had an effective PM program they wouldn’t have the emergencies.
The start of a PM Program doesn't have to be a "chicken or the egg" philosophical dilemma. Companies can, slowly but surely, reap the gains of a PM program by focusing their efforts on the work rather than on the idea of a program.
Old approaches to implementing a PM program have a spotty track record. It was often said that a PM program must be designed and sold from the top down, before it could be formally implemented. Some people imposed the requirement of a rigorous cost versus benefit analysis on the total program before it could be improved. This demand is often dictated in the face of firsthand and clear evidence that one dollar spent on a routine PM procedure could easily have saved two to three dollars lost on the last emergency repair performed.
Other grand efforts to implement a PM program are tied to the purchase of a computer program to run it all. If the purchase of the program is approved, the implementation of the PM program is quickly overshadowed by the initial data collection task required by many computer systems.
PM should determine a major portion of the work performed on a day-today or week-to-week basis. The work is preplanned. Labour estimates, material, and tool requirements are known. However, suggesting that PM is the most important work performed during a normal workday sometimes receives chuckles from people who work in maintenance. They know that, more often than not, PM work is the first to be displaced from the schedule by emergency work or other so called "more important work". The low regard PM has in some plants may be derived from a lack of quality and focus in the effort. Lots of time goes into the initial sale of a PM effort, but little time into the actual work performed.
Identify the equipment with high downtime, high maintenance, or repetitive repairs. This is usually a small percentage of the total equipment in the plant. ABC analysis (80 - 20 rule) or old fashioned "fat files" may help in this identification. In the absence of a formal cost justification, this list will certainly get you closer to the best result for each dollar spent. Take only the top one or two pieces of equipment on the list and attempt to identify the root cause of the problems most commonly encountered. A detailed review of work order history may yield the source. A brainstorming session with operations and maintenance personnel can be just as productive. PM programs which are developed with the involvement of operations have proven to be the most successful.
Next, develop a solid PM procedure to combat the root cause problem. Ah too often, a PM work order is handed to a maintenance worker without any more detail than a statement like, "PM the plant air compressor", or "Inspect the gearbox". The mechanic is expected to draw on personal knowledge of equipment and to do all the preventive work required. What is actually accomplished can vary widely from one employee to the next, and the work performed may not even be the work intended by the manager. The time taken out of the normal work day to perform PM should be productive. To improve the productivity, the work needs to be well defined. A written procedure with a data sheet should be developed for most PM work.
The following types of PM procedures should be considered:
INSPECTIONS
An inspection is usually performed on operating machinery using the basic senses of sight, sound, and touch. Unless specific parameters have been identified, the quality of the inspection is totally dependent on the sensitivity of the inspector to potential equipment problems. Associated checklists used on inspections are often just a list of equipment, the symptomatic conditions to be looked for, and a location on the checklist where a "check mark" is to be entered. Such checklists often become abused, with inspectors hurriedly filling in the check marks or even completing the forms back in the shop.
Inspections can be enhanced by adding gauges or instrument inspections to the route. Rotating components or drive belts can be inspected under the "freezing" action of a battery powered strobe light. Belt drive inspection can be expanded to include the use of sheave gauges and belt tension gauges. Critical temperature limits on bearings or compressor valves can be determined by using an inexpensive temperature infrared pyrometer. Vibration checks using low cost, pen-sized meters can be used to detect early problems in equipment due to imbalance, misalignment, or looseness. Adding such innovations to an inspection often raises the interest level of the inspector as well as heightens the quality of information returned.
ADJUSTMENTS
Adjustments involve the optimization of operating equipment. It could be a simple fine tuning of cam on a limit switch, or it could involve tuning a boiler combustion control system to maximize fuel efficiency. A record of adjustments made can become the basis for optimizing the PM frequency, or can point to the need for component replacement if too frequent adjustments must be made.
TESTING
Tests are used to verify that equipment is performing according to specifications. They are often associated with safety controls or environmental equipment. A typical PM of this type might be used to verify the automatic shutdown controls on a boiler steam drum.
CALIBRATIONS
A calibration is one which verifies or corrects the accuracy of critical indicators, control instrumentation, or final elements. A data sheet should be included which indicates "as found", "correct", and "as left" condition. These sheets should be signed and dated.
REBUILDS
A rebuild invariably requires equipment downtime. During such a rebuild, critical dimensions are checked and worn parts replaced. The goal of a rebuild is to restore equipment to "like new" condition. Rebuilds are sometimes turned over to an outside vendor. The vendor may be the original equipment manufacturer (OEM) or a service vendor familiar with the machinery’s maintenance requirements. In either case, the conclusion of the rebuild should include a detailed report covering what was done, what was found, what was replaced, and what should be checked on the next rebuild.
REPLACEMENTS
Replacement PM can involve the periodic replacement of disposable components, such as air, oil or fuel filters. Replacement PM can also include replace-in-kind for inexpensive but critical equipment. Often, such replacements are economically justified over more frequent inspections. A typical replacement PM would be replacement of inexpensive positive displacement fuel oil pumps at the beginning of the winter season.
Good PM procedures should incorporate the following elements:
The following sources will help in the development of PM procedures:
The development of a PM procedure is not complete until it has been performed and corrected. Solicit the remarks of people required to perform the procedure. If the procedure doesn’t work for them, it won’t be a successful effort. Additionally, reacting to their comments and giving their efforts visibility will improve involvement in the program.
After the procedure is corrected, the frequency of the PM may have to be adjusted. Obviously, if a failure has occurred between PM inspections, the PM procedure and frequency should be reviewed. Less obvious, but equally important, is the identification of PM work which is performed too often. As a rule, an effective PM program will generate three corrective action work orders, or on-the-spot repairs, for every 10 inspections performed. If a procedure doesn’t seem to be paying off in this way, the time between inspections should be extended. Frequencies left uncorrected undermine the credibility in the program for the people performing the work and those benefiting from the effort.
Once your first procedure is off and running, return to your list of equipment candidates for PM work and add new equipment and procedures to the program. When is the program complete? Many rightminded industrial organizations have adopted the seemingly unattainable goal of "all accidents are preventable." They know that the goal helps people focus on the ways to prevent accidents, i.e. reducing unsafe conditions and unsafe acts. A similar approach should be taken with respect to equipment failures in a plant. Focusing on a goal such as "all failures are preventable", or "all downtime is preventable", leads plant personnel to identify the causes of failures and discover ways to reduce them. Chances are you will never identify and solve all your equipment problems, but with your eye on the goal you’ll be headed in the right direction.
So, how do you eat an elephant? One bite at a time. Top management doesn’t have to know that you are embarking on an effort to overhaul or start a PM program. They probably don’t care, or think you’re already doing it. Small steps toward a complete program can be even more effective than first establishing a "master plan". However, prioritizing your effort should be an initial step.
Documentation is often required when performing these types of tests. They should include a form which shows the date and results of the test, and should be signed by the tester.
Michael V. Brown is a principle with New Standard Institute, based in Milford, Connecticut, a training and consulting firm dedicated to thje advancement of the maintenance profession through seminar, classroom and field training. This article appeared previous in Plant Engineering and Maintenance Magazine.
First published September 1996
