Facility Maintenance: Part 2

In part 1 of this series, we established the importance of maintenance activities in a business or production system and how effective maintenance enables a production system to operate efficiently.

In this article, we will discuss the different types of maintenance strategies at their basic forms.

There are different ways of classifying maintenance strategies, we will discuss the most common classifications which are listed below:

• Run to failure maintenance or reactive maintenance
• Time based maintenance or preventive maintenance
• Condition based maintenance
• Risk based inspection (RBI)
• Predictive maintenance.
• Corrective Maintenance

Let us explore these various types of maintenance strategies and their effects on the organizations that practice them.

Run to failure maintenance or reactive maintenance:

Just like the name signifies, this is a reactive form of maintenance, where the equipment is allowed to operate continuously till it breaks down. This form of maintenance is mostly practiced by organizations that do not have structured maintenance processes. This is the most basic form of maintenance.

Sometimes, run to failure or reactive maintenance can be deployed as a maintenance strategy by organizations with structured maintenance processes. Examples of such instances are as listed below:

• When the equipment is not critical to the smooth operation of the business or production system.
• When the cost of repair or replacement of the equipment is far less than the cost of maintenance activities.

As the organization advances in its maintenance culture, it gradually moves away from the reactive maintenance strategy to other more intuitive forms of maintenance.

Time based or preventive maintenance

This is scheduled maintenance activity at predetermined intervals such as 3-monthly, 6-monthly, yearly maintenance and 2-yearly maintenance. The level of detail or intrusive nature of the maintenance activities increases with the increase in time intervals. For instance, the 6-monthly inspection is more detailed than the 3-monthly maintenance.

The intervals between the maintenance activities are recommended by the equipment manufacturer and sometimes by subject matter experts.

This approach of maintenance comes with some disadvantages such as:

• Labor intensive – this requires lots of efforts and time for regular shutdown of equipment for inspections or services, even when the equipment is operating smoothly.
• Expensive – this method of maintenance is capital intensive. Requires both human and material resources to be deployed at regular intervals.
• Over maintenance – sometimes this could lead to unnecessary interruption of the manufacturing or production process.

Condition based maintenance

 This form of maintenance strategy involves real time monitoring of key operating parameters of the equipment against predetermined set points. Example is the monitoring of the temperature of an equipment; once the temperature rises beyond a set limit, usually recommended by the equipment manufacturer, the equipment is shut down for further investigation and repair.

This is a more effective maintenance strategy than the preventive maintenance as it only calls for shut down of equipment when there is an indication of a fault as signaled by the change in the monitored parameter.

This method of maintenance is usually deployed for very sensitive or critical equipment and allows for reduced interruption to operation when compared to the time-based maintenance.

In the next episode of this series, we will explore the remaining maintenance types:

• Risk based inspection (RBI)
• Predictive maintenance.
• Corrective Maintenance

See you in the next episode, thanks for reading

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