Pumps and Systems, February 2007
A large refinery or power plant may operate up to a dozen units of the same design, all installed 20 or 30 years earlier. In this mature equipment environment, some level of reactivity is a fact of life, at least initially. The trick is to react proactively, with tools that raise the plant's long term equipment reliability level.
A mature plant that has been neglected for some time requires that problem areas be addressed first and that they be moved through a series of steps:
1. Reactive Response
Obviously, equipment that is broken must be fixed first. To be effective, even in a reactive mode, the maintenance operation must be able to identify, prioritize, plan and schedule work; operate and maintain a CMMS that drives a reasonable time-driven Preventive Maintenance schedule; manage materials and other resources to support the execution of work.
If the maintenance organization needs training to reach this level of operation, then provide the time and resources. This is the necessary starting point (Stage I) for many companies.
2. Proactive Reactivity
Once PM and repairs are being scheduled and executed effectively, implement a Reliability Continuous Improvement (RCI) initiative that focuses on perennial equipment problems and stamps them out in a series of short projects that enhance the equipment as it is being repaired.
In the mature equipment world, perennial problems typically develop where equipment has a combination of problems. RCI addresses this situation by analyzing the mix of material, equipment, engineering, training, and other causes that contribute to the perennial problems. Properly planned - and with unrelenting follow-through on projects - this initiative can eliminate the 10 percent of equipment problems that cause 90 percent of production losses. This is the second step (Stage II) for many companies.
Proactive tools typically include condition monitoring, further craft skills enhancements, refinement of equipment history capture, and the development of true asset healthcare strategies for key equipment. With mature equipment, a survey of potential failure modes may have to be postponed to pursue solutions to actual failure modes.
To start, use Cost of Unreliability (CoUR) analysis and safety reporting to identify the equipment that causes the most grief. CoUR combines some costs that are already being tracked, such as maintenance labor and material, lost production, and expedited shipping, overtime, equipment rental, etc. Assign these costs to the equipment groups that cause them. The result can be expressed as a graph like Figure 1. Note that the X-axis is not time, but rather it is the company's "fleet" of equipment.
Figure 1. Equipment Failure Pareto - CoUR (Cost of Unreliability).
Pareto's rule nearly always applies to this kind of distribution. Five to 20 percent of all equipment will be causing 80 to 90 percent of CoUR. Start here for two reasons: 1) it delivers the most improvement for the resources spent; 2) it helps the rest of the organization understand that reliability engineering focuses on the same goals they do - safety, quality, productivity, and cost management. Once the most significant problem equipment is identified, the RCI steps are set into motion: