How to Decide Equipment Criticality.

The equipment criticality section of the eBook “The Maintenance War — The Japanese Path To Maintenance Excellence”

You can read this maintenance equipment criticality article below, and/or listen to it (Via narration placed in the video below). The same is true with the whole ebook, it is available in PDF or Audio format.

Before I get on to the “How to Decide Maintenance Criticality Ranks” section, for context, first we will view an excerpt from the introduction part of the eBook “The Maintenance War” in order…

[ You will learn about a number of diverse topics in the next few pages. You will read about how this particular Japanese company determined its equipment and component criticality. You will learn about a new, truly effective way, of making next year’s maintenance plan. You will learn about condition monitoring in the Japanese way. The Japanese are great maintenance investigators and you will be impressed when you learn how they do their failure analyses. We will also cover their psychology of maintenance — the way they think about maintenance and how they look at it. You will be astounded by their mindset.

The report is divided into three broad sections. Planning Maintenance shows the methods used by this Japanese chemical company to arrive at its daily work activities. Implementing Maintenance explains the methods used to arrive at which activities are required. The Maintenance WAR explains the mindset of the Japanese involved in operating and maintaining plant and equipment. ]

How to Decide Maintenance Criticality Ranks:

How do you decide what level and type of maintenance to use on an individual item of plant and its sub-assemblies? Not all equipment is equally important to your business. Some are critical to production and without them, the process stops. Others are important and will eventually affect production if they cannot be returned to service in time. While other items of plant are not important at all and can fail and not affect production for a very long time.

As a maintainer, you want to know which equipment in your plant falls into each of those categories so you can determine your response. Furthermore, you want to know which sub-assemblies in each item of equipment are critical to the operation of the machine.

From this information, you can decide which spares to hold on-site and which to leave as outside purchases. The equipment criticality also determines what level of preventative maintenance to use, what type and amount of condition monitoring to use, and what type and amount of observation is required from the operators. You can also use it to justify online monitoring systems to protect against catastrophic failure.

The western approach to determining criticality is often to use either Reliability Centred Maintenance or Risk-Based Maintenance to determine the consequences of failure and then address the appropriate response to prevent the failure. The Japanese chemical manufacturing company I visited had a novel way of determining its equipment criticality. They based the equipment and component criticality on the knock-on effect of a failure and the severity of the consequences. It is the same intention as the previously mentioned methods but they arrive at the rating and the response to it in a unique, quick four-step process.

They used a simple flow chart that production and maintenance worked through together, equipment by equipment. Those failures that caused safety and environmental risks were not allowed to happen and either the parts were carried as spares and changed out before failure or the plant item was put on a condition monitoring program. Those failures that caused production loss or affected quality also were either not allowed to happen or put into a condition-monitoring program. And those failures that didn’t matter were treated as a breakdown.

The flow chart lets one arrive at a rating and a corrective action for each piece of equipment and component fast. No need to spend hours and days looking at failure modes and deciding what to do about them. If an equipment or component loss produced dangerous situations, or if the failure stopped production or affected quality, it was either changed out before the end of its working life or it was put on a monitoring program.

The maintenance philosophy for every bit of the plant could be arrived at in a four-step decision process. It was very easy to use and to decide what action to take.

The SABC is the criticality rating scale. On the chart, you notice that equipment gets an ‘S’ rating when it is never permitted to fail because of serious danger to life and the environment from a failure. Under the ‘S’ rating parts are replaced before they reach the end of their working life.

An ‘A’ rating also requires parts to be changed before the end of their working life but that is because of the production problems a failure would cause. A ‘B’ rating required condition monitoring. And a ‘C’ rating meant breakdown maintenance was acceptable. The SABC chart is both a criticality scale and a maintenance strategy decision tree.

Equipment Criticality Sub-assemblies Ranking

The SABC criticality-rating chart was also used to determine the critical parts within the machine. The same decision logic was applied to the equipment’s components. From that review process, the critical spares were determined and a decision was made to either stock them or monitor their condition and look for deterioration.

Parts that must never fail were changed out in a time-based cycle, parts that wore out unpredictably were monitored and parts that did not matter if they failed were brought in when they broke.

Maintenance Task List

Once the criticality ratings are determined for each machine, and its components, a spreadsheet is developed listing the applicable maintenance strategy and the maintenance tasks to be used on the equipment.

The complete maintenance philosophy, spare parts requirements, condition monitoring requirements, and preventative maintenance frequency for every item of the plant are all there on one sheet for all to see.

With this spreadsheet done first, it is easy to transfer all of the required inspections and checks into a CMMS and generate preventative maintenance work orders to care for the equipment.

I hope you found this article interesting and share it with your associates and friends. If you would like to read (or listen to) The Maintenance War eBook, please see https://bin95.com/ebooks/maintenance_excellence_review.htm

Thank you all for your support, it has been much appreciated.

Published By: Business Industrial Network BIN95.com

Originally published at https://www.linkedin.com.