The benefits of condition monitoring & condition based maintenance

My friends at Asian Power asked if I would do an article so I decided to do one on what I know best - Rotating Equipment Maintenance.

To gain the maximum benefit possible maintenance must be performed under a well planned and structured Program. The Program should be specifically tailored to the equipment operating requirements and environment.

Examples of conditions that should be considered in developing the Program are:

• Full load or part load operation; number of starts and stops; normal ambient temperatures; harsh or clean environment; fuel or steam quality.

Following are what I consider to be the major aspects of a planned and structured Program.

Maintenance Plan
A well structured Maintenance Plan should include:

• A plan for accomplishing periodic Preventative Maintenance and Inspections: Weekly, Quarterly, Semi-Annual, Annual
• Overhaul and major repairs planning and scheduling
• Unscheduled maintenance plan
• Stocking of maintenance spares;
• A plan for correction of discrepancies categorized into immediate action, on availability of parts, on next planned shutdown, on next planned maintenance

Condition Monitoring
Condition Monitoring is No. 1; the continuous monitoring of the condition of the turbine, driven equipment, and ancillaries in order to make sound and cost effective maintenance decisions. This includes: operating parameters, events such as alarms and trips, maintenance performed, spare parts utilized.

Trending and Root Cause Analysis
This is most critical step to achieve increased reliability/availability and lower maintenance costs. Every operator I have dealt with has tons of data on the equipment operation but it’s either stored in the computer or a desk drawer. The key is to use this data to make cost effective decisions.

For older equipment much of this is done manually. Current state of the art control systems have the ability to do trending and provide a level of diagnostics but I have found many operators are not trained to utilize the full capability of these systems.

• If operating parameters are staying stable no action is required even if the Maintenance Plan shows scheduled maintenance
• If key operating parameters are starting to show adverse trends it is time to take action by analyzing the true reason and determining the maintenance action required prior to a failure
• Trending will also assist in planning for major inspections and overhauls
• This requires and dictates
• Recording of operating parameters
• Recording of all alarm and shutdown events
• Root Cause Analysis; what is the true cause
• Recording of maintenance actions taken
• Adjustment of Maintenance Plan based on above

Condition Based Maintenance (CBM)
CBM is scheduling and performing maintenance based on equipment and hardware condition and not on a “hard time” given by the OEM.

Development of Key Performance Indicators (KPI’s)
To track and measure improvement against key factors effecting operating performance and costs KPI’s should be developed. KPI’s should be broken down into measurable and understandable events. Examples are:

• Fail to starts
• Turbine trips
• Lost time due to spares availability

These KPI’s will show how effective the periodic maintenance and inspection program and the CBM program are.

What are the benefits of a Planned and Structured Maintenance Program
The benefits are what all operators are looking for:

• Increased reliability and availability
• Maximized production output
• Lower maintenance costs
• Lower inventory stocking costs

Gary J Keller, Rotating Equipment Specialist, Keller & Associates Turbine Services