on Maintenance Reliability

THE VITAL DIFFERENCE BETWEEN USING CONSEQUENCE OR CHANCE REDUCTION STRATEGIES IF YOU WANT OPERATIONAL EXCELLENCE RESULTS, IS CONSEQUENCE REDUCTION REQUIRES REPAIRS AND MAINTENANCE, WHEREAS CHANCE REDUCTION REMOVES REPAIRS AND MAINTENANCE.

In reading “Enterprise Asset Management Success the Plant Wellness Way for CEOs and Senior Executives” I was interested in your table on page 15 that showed risk based inspection and condition based monitoring techniques as consequence reduction strategies.

My understanding is that both RBI and CBM are specifically designed to prevent failure through reducing the likelihood of failure i.e. by detecting failure before it happens within timescales that allow mitigation action to be taken. In the API 581 RBI standard, consequence is treated as a constant over time so the methodology specifically targets risk reduction through more effective inspection or design changes.

I appreciate that this is only a small point in terms of the overall approach and key messages challenging readers, but if you have time to reply I would like to understand the reasoning behind not viewing RBI and CBM as chance reduction.

Hello Paul,

When I developed the table I decided that if a technique or methodology required a failure to start in order to provide evidence that failure had been initiated, then it fell into the consequence reduction strategy. Once an embryonic failure existed then the eventual outcome COULD be complete failure if circumstances went badly. CBM and RBI look for evidence of failure, in fact they need a failure to have started in order to provide the signal that the P-F degradation has begun.

The Physics of Failure Factors Analysis for selecting maintenance strategy is a one-person exercise that identifies all ways a component can physically fail. Equally important to its simplicity is its ability to select the most effective life cycle strategies for maximising reliability. Another powerful business advantage is the failure-addressing solutions arrived at are universal solutions that apply to every other identical component, whatever equipment it is in. Do a Physics of Failure Factors Analysis for one part and you do it for all identical parts for the life of your operation. It is a highly accurate and cost-effective maintenance strategy selection methodology.

Charting historic equipment failure events visually shows the Failure Probability Density Function curve for that equipment. It is also known as a Failure Density Distribution Curve.

VALUE OF A DISTRIBUTION CURVE

Failure Probability Density Function curves, Failure Density Distribution Curves contain useful information about what has happened to equipment. These curves illustrate the chance of failure of an equipment over a period. Here, our fixed variables are the equipment’s components’ material-of-construction and design. As such, the only changing variable is the operating and maintenance strategies, including work processes, used by the company.