Condition-Based Maintenance P-F Curve Theory
Inspecting assets too frequently wastes technician labor; inspecting too infrequently risks missing the P-F window, leading to catastrophic secondary damage and unplanned plant trips.
Intermediate Category: Maintenance Planning & Strategy • ~5 min read
P-F Interval & Inspection Planner
Establish non-destructive inspection frequencies that guarantee early failure detection.
Q:
What is the P-F Interval rule for condition monitoring?
The P-F interval is the time between when a potential failure (P) first becomes detectable and when functional failure (F) occurs. Reliability engineering standards mandate inspection intervals of: I ≤ (P - F) / 2. This ensures at least one inspection occurs during the warning window with net turnaround time: Tnet = (P - F) - I ≥ Tlead.
P-F Parameters
First detection via vibration, thermography, or oil
Parts procurement + crew mobilization window
P-F Interval (Δt)
720 h
Detection window
Max Inspection Interval
360 h
Δt / 2 policy
Net Warning Time
360 h
Before functional failure
Annual Checks
25
$3750/yr
Strategy Assessment: Feasible Condition-Based Maintenance (CBM). Inspecting every 360 hours guarantees at least 360 hours of net warning to execute corrective turnaround before functional failure.
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Engineering & Regulatory Notice: The calculations, projections, and failure models provided in this suite are for engineering estimation and educational purposes. Verify all calculations and assumptions independently before making operational, equipment replacement, safety-critical, or regulatory compliance decisions.
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