Myth 2. RCM should only be applied to critical assets

The advice to apply RCM to only critical assets, offered by many consultancies, is an attempt to counter the effects of Myth 1. This goes to the heart of why these myths can be counterproductive, instead of dealing with the issue of inefficient implementation; focus often turns to tampering with the method itself.

There are two issues here that need to be dealt with; first what exactly is criticality and second what are the benefits of RCM over a larger asset base.

Criticality is probably one of the most overused terms within the field of asset maintenance. At its core it is an attempt to determine the relative importance of assets within a company, plant or process.

The reasons are many and include sequencing of assets for analysis and other improvement efforts, the prioritization of corrective works in progress, and the determination of which capital spending.

However, with a lack of an agreed upon definition for criticality we see a range of methods, used in a range of ways, all of which clouds the issue relating to criticality and relative importance assessments.

So what is more important? An operational pump with no back up that will take out processes at a rate of $10,000 per hour once it fails; or a hydraulic pump that closes a gate on the entrance to the plant? And… there is an additional entrance to the plant.

It appears to be an obvious question, on the face of things it would appear that a loss of $10,000 per hour wins hands down.

But how about if the failure of the relief valve on the hydraulic pump, under fault conditions, caused the gate to close with fatal pressure, creating a potential hazard to life?

Now the entire dynamic changes, after detailed analysis the pump may still be more critical, or maybe not. The point is that you cannot determine true criticality without understanding all of the reasonably likely failure modes, and their impacts, of the asset under consideration.

This is not an isolated example; many analyses of “non-critical” assets have produced critical failure modes.

In a recent evaluation of pumping stations for a European utility many of them were classed as high criticality due to the populations and volumes that they managed. On review it was found that due to the gases that were present at some of the lower criticality sites they actually had consequences of failure far higher than some of their “more important counterparts.

It is obviously inefficient to analyze all assets to a failure mode level in order to determine which should be included in an RCM analysis. But when it is done at an asset level, rather than at a failure mode level, is often a prioritization approach of the primary function of the asset; or it is based on guesses and assumptions.

Even so, prioritizing assets based on their primary function and its relation to corporate objectives is a perfectly valid and justifiable practice; even if it is not based on real criticality.
So should RCM be applied to only high importance assets?

There are many documented and reported benefits of a rigorous implementation of Reliability-centered Maintenance. However, one that everybody seems to agree on is that where there is an existing maintenance schedule in place, it will provide a dramatic reduction in routine tasks. (Moubray quoted this as up to 70% in some cases)

If we restrict the application of RCM to assets of high importance only, then we are ruling out a reduction of routine maintenance over the remainder of the asset base.

As this series has already illustrated, the impact of many assets cannot be established until their failure modes and their consequences have been identified. So by restricting the RCM process we are also leaving assets that may have potentially large scale failure consequences in the areas of safety or operations.

The benefits of RCM are well established and there is no need to go through all of them here.

In brief, they include;

• reduction of levels of risk of failure,

• increases in cost effectiveness,

• increases in effective labor utilization,

• turnaround scope planning, and

• feeding sophisticated techniques on whole-of-life asset management and risk-distributed budgeting

If RCM can be implemented in a rapid and beneficial manner, then any approach that restricts the scope of the analysis project also restricts the value we are able to get out of the physical asset base. Does this mean RCM should be applied to every asset? Probably not; but it should definitely be applied to the majority if it is cost effective to do so.

If this article was of interest to you I hope you would recommend it to others within your operations. Please feel free to send me an email regarding this or any other themes on this site.