How should a plant establish a reliable condition monitoring baseline?
A baseline is a documented reference for a healthy asset under known operating conditions. It makes later changes easier to interpret, but it is not a universal alarm limit or proof that the machine has no hidden defects.
Confirm the asset is ready to baseline
Verify commissioning and acceptance checks are complete, the asset is operating within approved limits and known defects have been addressed or explicitly documented. Record the equipment tag, configuration, sensor locations, date, instrument identification and the person who collected the data.
Capture operating context with every measurement
- Load, speed, flow, pressure, temperature and product or process conditions as relevant.
- Steady-state versus transient operation, including startup or shutdown when specifically required.
- Measurement location, orientation, sensor mounting method and instrument settings.
- Lubricant type, recent maintenance and any significant equipment modifications.
- Calibration or verification status for instruments where required by the procedure.
Comparing a lightly loaded pump to a heavily loaded pump without context can create misleading alarms. A change in process duty can change vibration, temperature and electrical signatures even when no defect has developed.
Select methods that match credible failure modes
Vibration trends may support detection of certain rotating equipment problems. Infrared thermography can reveal temperature differences, while oil analysis can track contamination or wear indicators. Ultrasound and electrical testing have their own applications and limitations. Select techniques based on failure mechanisms and consequence, not merely on which sensor is available.
Establish repeatability before thresholds
Collect more than one stable reading where practical. Compare readings at similar operating states, and investigate unexplained variation. Set alert thresholds using manufacturer limits, applicable technical standards, failure history and engineering judgment. Do not treat a single healthy reading as a statistically reliable limit.
Example of a baseline error
A motor's vibration baseline was collected with a valve nearly closed. Later, a route reading is taken at normal flow and appears higher. The difference may reflect operating conditions rather than deterioration. Recording valve position and process duty would make the comparison more meaningful. The example is illustrative.
Define who responds to a change
Specify the analyst, confirmation method, escalation threshold, work order process and response deadline. Rebaseline after significant repair, replacement or configuration change, while retaining historical data and documenting why the reference changed.
Review the program's outcomes
Track actionable findings, false alarms, missed failures and the time between detection and corrective action. A baseline supports reliability only when findings lead to timely, controlled decisions.
Explore the assessment
KANE can help match monitoring methods and inspection frequencies to equipment failure modes.
View the related assessment →Related answer: How should a plant use the P-F interval to set inspection frequency?
Technical references
NASA Reliability Centered Maintenance Guide · PNNL Maintenance Approaches · DOE O&M Best Practices