Learn more about how the I-P Interval can help maximize reliability
The Potential Failure (P-F) Curve is a chart used to assess the condition of an asset and its progression toward failure. The X-axis represents the time to failure, and the Y-axis represents resistance to failure. Using the P-F Curve for insight can help you extend the life of your assets and minimize failures.
The P-F Curve originated from a Department of Defense study, which found that managing assets based on their condition was more effective than calendar—or age-based—maintenance.
Every inspection method detects potential failures at a different point. More sensitive tools and more frequent inspections lead to earlier detections of failure, which can have immense benefits for an organization. The value of taking maintenance actions decreases the closer you get to failure. Potential failure, or PF, is when failure can be detected and degradation begins. Functional failure, or FF, is when an asset no longer performs as intended. It does not necessarily mean that the asset is beyond repair.
Most organizations focus their maintenance efforts on the P-F Interval, which includes the time between when potential failure is detected and when an asset reaches functional failure. As organizations move along their reliability journey, they reach a point where they can focus on the I-P Interval instead. Extending this interval means performing maintenance actions to prevent failures before they occur, and should be among the goals of mature organizations.
The P-F Curve starts with asset design and installation. The I-P Interval represents the time between equipment installation and when potential failure begins. Lengthening this timeframe requires precision and planning—ensuring that all components have the correct fit, clearance, alignment, and more. Creating installation standards is one way to eliminate some common recurring failures (such as leaks caused by the use of incorrect or substandard materials). During the I-P Interval, failure can be prevented—not just delayed.
Precision alignment and balancing can improve the lifespan of rotating equipment by reducing the vibration that leads to failures related to bearings, seals, and couplings. When properly aligned, assets experience less unplanned downtime, have a longer lifecycle, and consume less power. This can be accomplished using precision tools and techniques such as laser shaft alignment.
PRUFTECHNIK invented laser shaft alignment in the 1980s. Our newest laser shaft alignment tool, the ROTALIGN touch, takes advantage of today’s technologies to offer sophisticated capabilities that boost ease of use, including:
Additionally, an integrated camera enables visual documentation, meaning subsequent alignment jobs are more straightforward.
The ROTALIGN touch makes it easier to transition from focusing on the P-F Interval to the I-P Interval. After all, the goal of reliability is not just to reduce failure, but ultimately to eliminate it. By moving your focus on the P-F Curve back to the I-P Interval, your organization can avoid the most significant number of failures and realize the highest amount of savings.