Inspectioneering Journal

Maximizing the P-F Interval with Predictive Maintenance

By Bryan Christiansen, Founder and CEO at Limble CMMS. This article appears in the November/December 2019 issue of Inspectioneering Journal.


Implementation of a successful Predictive Maintenance system requires a good working knowledge of the P-F Interval. Proper application of this principle allows for early detection of equipment anomalies, which lowers the maintenance burden and lessens the impact to operations. With the proliferation in industrial digitization, detecting problems before a failure occurs is easier today than ever before.

This article will introduce the P-F Interval and its importance in predictive maintenance, describe methods to detect failures early, and map out a path to begin an effective Predictive Maintenance program at your facility.

P-F Interval

First, let us understand the P-F Interval. In an old-fashioned maintenance model, the operations team ran the equipment until it failed. The maintenance team then reacted, repairing the equipment as soon as they could. As maintenance strategy became more preventive, tasks to check on equipment or replace parts were added on a periodic basis. This was an improvement, but it was difficult to optimize the timing of the tasks. The preventative maintenance (PM) task had to be performed before issues were to become failures. The cycle of PM-to-failure could vary widely; thus, the maintenance team could either overcommit to PMs, or risk failures.

The P-F Curve
Figure 1. The P-F Curve

This content is available to registered users and subscribers

Register today to unlock this article for free.

Create your free account and get access to:

  • Unlock one premium article of your choosing per month
  • Exclusive online content, videos, and downloads
  • Insightful and actionable webinars
Interested in unlimited access? VIEW OUR SUBSCRIPTION OPTIONS

Current subscribers and registered users can log in now.

Comments and Discussion

Posted by Sairaman Govindaraj on December 30, 2019
The article is useful. The information and... Log in or register to read the rest of this comment.

Add a Comment

Please log in or register to participate in comments and discussions.

Inspectioneering Journal

Explore over 20 years of articles written by our team of subject matter experts.

Company Directory

Find relevant products, services, and technologies.

Training Solutions

Improve your skills in key mechanical integrity subjects.

Case Studies

Learn from the experience of others in the industry.


Inspectioneering's index of mechanical integrity topics – built by you.

Industry News

Stay up-to-date with the latest inspection and asset integrity management news.


Read short articles and insights authored by industry experts.

Expert Interviews

Inspectioneering's archive of interviews with industry subject matter experts.

Event Calendar

Find upcoming conferences, training sessions, online events, and more.


Downloadable eBooks, Asset Intelligence Reports, checklists, white papers, and more.

Videos & Webinars

Watch educational and informative videos directly related to your profession.


Commonly used asset integrity management and inspection acronyms.