Page 38 - Root Cause Failure Analysis

Root Cause Failure Analysis Methodology 29

information provided in these manuals is essential to effective resolution of plant
problems.

Objectives of the Review
The objective of the design review is to determine the design limitations, acceptable
operating envelope, probable failure modes, and specific indices that quantify the
actual operating condition of the machine, equipment, or process system being inves-
tigated. At a minimum, the evaluation should determine the design function and spe-
cifically what the machine or system was designed to do. The review should clearly
define the specific functions of the system and its components.

To fully define machinery, equipment, or system functions. a description should
include incoming and output product specifications, work to be performed, and
acceptable operating envelopes. For example, a centrifugal pump may be designed to
deliver 1,OOO gallons per minute of water having a temperature of 100°F and a dis-
charge pressure of 100 pounds per square inch.

Incoming- Product Specijications
Machine and system functions depend on the incoming product to be handled.
Therefore, the design review must establish the incoming product boundary condi-
tions used in the design process. In most cases, these boundaries include temperature
range, density or specific gravity, volume, pressure, and other measurable parame-
ters. These boundaries determine the amount of work the machine or system must
provide.

In some cases, the boundary conditions are absolute. In others, there is an acceptable
range for each of the variables. The review should clearly define the allowable bound-
aries used for the system's design.

Output- Product Specijications

Assuming the incoming product boundary conditions are met, the investigation
should determine what output the system was designed to deliver. As with the incom-
ing product, the output from the machine or system can be bound by specific, measur-
able parameters. Flow, pressure, density, and temperature are the common measures
of output product. However, depending on the process, there may be others.

Work to Be Per$omed
This part of the design review should determine the measurable work to be performed
by the machine or system. Efficiency, power usage, product loss, and similar parame-
ters are used to define this part of the review. The actual parameters will vary depend-
ing on the machine or system. In most cases, the original design specifications will
provide the proper parameters for the system under investigation.