Critical Spares Analysis - What's the Problem?

January 31, 2019

We recently completed a project for a mining client where the brief was to review critical spares. They had previously identified critical equipment. The manager assumed that the critical spares associated with his equipment would be in a register and the spares were being managed by supply.

When the manager realised that the register was not only out of date, incomplete, inaccurate and in some cases lacked sound logic around criticality. He gave us a call to assist. We found that there was also not a good understanding of what constituted a critical spare.

The site expressed that they did not have enough critical spares, that those which were catalogued would probably not be in stock or may not be in good working order. The general perception was that the risk of downtime because of poorly managed critical spares was high.

Maintenance personnel developed this idea because, in the past, even basic maintenance, repair and operational (MRO) spares had cost them downtime which they felt should have been avoided.
The problem of poor spares management is common across the industry. The root cause generally stems from inadequate asset management strategies and maintenance plans. Many sites forget that spares are simply another way to manage the risk of asset failure in the same way as maintenance tactics; only they’re intended to mitigate the consequences of asset failure rather than make a failure less likely.

We believe that the best way to conduct a critical spares analysis is to conduct a site-wide asset criticality assessment to first identify/confirm critical systems and equipment. Then to check the maintenance strategies in place to ensure they are effective.

We use a Bluefield criticality assessment tool to determine the mitigated and unmitigated (based on the current maintenance strategy) criticality ratings for every asset. The tool imports the asset hierarchy from the ERP, and assigning likelihood and consequence factors to each asset, allows calculation of a hazard and process criticality severity ranking.
We then prioritise developing/reviewing asset management plans based on the criticality assessment results.

The key elements of the asset management plans define the asset's productive life, operating context and operational limits, as well as their scheduled downtime, condition monitoring and component change-out strategies. We've previously written about the value of asset management plans

The analysis of spares criticality can be carried out quickly and easily after the context and understanding of the asset management plans, based on criticality, is well understood.
When working on-site it is easy to feel like you have little control over their critical spares. The problem often is with all the spares, not just the critical ones.

While in maintenance we feel we don’t have a lot of control, we need to understand that we must trigger a demand signal (requirement) on supply to deliver the part. We should not just assume that supply knows what parts we want and when we want them. Our maintenance planners should use the asset strategy to help supply set the right stocking strategy. Avoid relying on inventory optimisation tools to do this.

As a result of the project, we were able to deliver for our client a full critical spares analysis and recommendations for completing or updating asset management plans for around three dozen of its most critical assets. The project also highlighted for the client, several gaps in the understanding of the condition of their assets, or tactics needed to manage them. The benefits will therefore extend beyond those the client intended to achieve with the original project brief; namely fewer unplanned failures due to a more effective asset management plan.

Our experience concerning critical spares analysis has been to understand asset criticality first and foremost. This must be carried out over the entire reach of the operation. Then investigate the effectiveness of the asset management plans. Only then can we get control over our critical MRO spares.