Overview

A significant portion of a plant or systems reliability is determined during the initial design and construction. Choices concerning configuration (e.g. redundancy), and robustness, will determine the inherent reliability of the plant or system.

Inherent Reliability:

The inherent reliability of a plant, system or device is the maximum achievable reliability based on configuration and component selection. If operated correctly, maintained correctly and inspected on appropriate intervals, it will be possible to attain the full inherent reliability. If poorly operated, poorly maintained or allowed to develop and retain defects, the reliability can be significantly less than the inherent reliability

Although the inherent reliability defines the upper limit for performance as initially designed and constructed, work management processes that can be enhanced by Maintenance Excellence will determine:

1. How close to inherent reliability the asset will perform.

2. If the inherent reliability will be increased or decreased as the asset ages and is modified.

Let's discuss these two issues separately.

Achieving Inherent Reliability

The ability to achieve the full inherent reliability of a plant or system depends on restoring the features that determine the inherent reliability whenever maintenance work is done.

For example, when a pump is maintained in a 'shortcut" manner, its reliability will not be as good after maintenance as it was before maintenance. In many instances, the reason why equipment is maintained in a "shortcut" manner can be found in the Routine Maintenance Process (RMP) or the Turnaround Process (TAP).

If the...