Why the Original Model of the P-F Curve Is the Correct Model

Overview of the P-F Curve

Origin: Introduced by John Moubray, founder of Aladon.
Purpose: Illustrates the time interval between potential failure (P) and functional failure (F) of a physical asset.

D-I-P-F Curve Misconception:
- Includes aspects like design integrity (D-I) which are deemed technically incorrect.
- Marius Basson argues that the P-F Curve is the correct model as it focuses on the failure characteristics and intervals.

P-F Interval: Valid for assets where failure onset is random, providing detectable warnings.
Functional Failure: Does not always mean complete failure; relates to performance standards defined by users.
Time Irrelevance: Contrary to some beliefs, potential and functional failure are not necessarily time-based.

Design Integrity (D): Incorrectly positioned on the curve; design attributes like quality and reliability are necessary but not directly tied to P-F interval.
Precision Maintenance (I-P Interval): Not a prerequisite for P-F interval; real-world practices show predictive maintenance starts immediately.
Preventive Maintenance: Should not be depicted as sequential to P-F; differing failure characteristics necessitate separate strategies.
Run-to-Failure: Incorrectly aligned with P-F; it's a separate strategy when failures are tolerable or when P-F interval is too short.

Cost Implications:
- Predictive maintenance cost may rise as failure nears (shorter P-F interval).
- Longer intervals allow more cost-effective corrective maintenance.

Not considered a strategy but a method of addressing failures using various risk management strategies.

The P-F Curve focuses on detecting and addressing failures through predictive or condition-based maintenance (CBM).
Combines design, preventive, and predictive strategies in a timeline may lead to misunderstandings.

The article argues for the standalone validity of the P-F Curve in illustrating asset failure processes without incorporating unrelated maintenance strategies.