The time interval between the points P and F on the curve is called the “PF Interval”.Some time after the point P, the item will suffer a Functional Failure – it will no longer be able to fulfil its intended function.Note that, at the point P, the equipment is still functioning – it has not yet suffered a “Functional Failure” (another RCM term with a specific meaning). This is called the point P on the curve – the point at which we can first detect the “Potential Failure” – a term which has a specific meaning in RCM terminology. It may only be some time after the point at which the incipient failure has been initiated that we can first detect that the failure is occurring.However, once the failure starts, then it is assumed that resistance to failure will continue to decrease over time.Indeed the incipient failure may be initiated by a random event, such as impact loading, a random overload etc. The point at which the failure starts need not necessarily be coincident with the item entering service.vibration analysis) may be able to detect mutiple failure modes, but each of these failure modes will have their own PF Curve. Some condition monitoring techniques (e.g. The PF Curve applies at a Failure Mode level – that is, it applies to one Failure Cause.It can be visualised as shown in the diagram below. In essence it was intended to illustrate a fairly simple concept associated with selecting a Condition-Based inspection (or Predictive Maintenance) task to deal with a specific failure mode, which was nonetheless not well understood at the time. The term P-F interval is a core concept of Reliability Centered Maintenance (RCM) and was first coined by the late John Moubray in his book RCM II. What is the PF Interval?īefore starting, let’s give a brief introduction to the PF Interval. But with more and more equipment being fitted with real-time asset health monitoring equipment and with the advent of Predictive Analytics and Big Data, is it really relevant anymore? In this article, we will discuss the PF Interval, how it is applied and whether it can be applied to equipment fitted with real-time health monitoring and where equipment health is assessed using Predictive Analytics and Big Data. The PF Interval is a key concept when selecting preventive maintenance tasks. Analyse root causes and eliminate defects.

Optimise your preventive maintenance program (RCM and PMO).Establish operational and maintenance readiness.

Improve your shutdown / turnaround performance.

Select or implement a CMMS / ERP system.Improve your maintenance planning and scheduling.Develop an asset management strategy or Strategic Asset Management Plan (SAMP).

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