root cause analysis

Basic Elements of a Comprehensive Investigation
By Mark Galley, ThinkReliability

The terms failure analysis, incident investigation, and root cause analysis are used by organizations when referring to their problem solving approach. Regardless of what it’s called there are three basic questions to every investigation: 1 - What’s the problem(s)? 2 - Why did it happen (the causes)? and 3 - What specifically should be done to prevent it.

Solving problems effectively is part of being an effective organization. The individuals and groups that tackle problems in organizations today sometimes inadvertently focus on the people or departments involved rather than the specific causes of the problem. This creates an organizational culture that focuses more on blaming other groups and individuals than preventing problems from occurring.

Organizations apply a variety of tools to solve problems, improve operations and increase reliability—many times without success. Why? More than likely, they make one or a combination of six common errors:

1. They focus on blame.
2. Conducting root-cause analysis, they focus on finding one “cause.”
3. They consider a problem description and problem analysis the same thing.
4. They start an investigation by trying to find the problem, instead of identifying an organization’s
goals
5. They apply “buzzwords” instead of the basic technique of cause-and-effect.
6. They use select problem-solving tools for select circumstances.

Overcoming these errors involves knowing why they happen and how to prevent them. Armed with this knowledge, both employees and managers can improve problem-solving in any organization.

5-3
Bearings have no wearable surfaces, they are instead designed to fatigue after many hours of service.

In a properly operating bearing the race ways and rolling elements will become dull in appearance. This dullness is not an indication of wear and has no affect on the life of the bearing. These dull surfaces form visible paths, so their appearance and location is important in analyzing any type of bearing failure.

When we install a bearing into a piece of rotating equipment the general rule is to have the interference fit on the race that is rotating and, therefore, carrying the load. Almost all centrifugal pumps, motors, and a high percentage of other types of rotating equipment have the bearings installed with the inner race an interference fit and rotating with the shaft . The outer race remains stationary, or in a fixed position.