Page 362 - Intro Predictive Maintenance

A Total-Plant Predictive Maintenance Program 353

How do you decide which techniques will provide a cost-effective method of con-
trolling the maintenance activities in your plant? The answer lies in determining the
type of plant equipment that needs to be monitored. Plants with a large population of
electrical equipment (e.g., motors, transformers, switch gear) should use thermo-
graphic or infrared scanning as their primary tool, whereas plants with a large popu-
lation of mechanical machines and systems should rely on vibration techniques. In
most cases, your plant will require a combination of two or more techniques, but you
may elect to establish one technique as an in-house tool and contract with an outside
source for periodic monitoring using the secondary techniques. This approach would
provide the benefits that the secondary techniques provide without the additional costs.

16.1 THE OPTIMUM PREDICTIVE MAINTENANCE PROGRAM
The optimum predictive maintenance program will, in most cases, consist of a com-
bination of several monitoring techniques. Because most plants have large popula-
tions of mechanical systems, vibration techniques will be the primary method required
to implement a total-plant program.

16.1.1 Predictive Technologies

Vibration methods alone cannot provide all of the information required to maintain
the operating condition of the plant. It cannot provide the data required to maintain
electrical equipment or the operating efficiency of nonmechanical equipment. There-
fore, secondary methods must be used to gain this additional information. At a
minimum, a comprehensive predictive maintenance program should include:

• Visual inspection
• Process dynamics
• Thermography
• Tribology

Visual Inspection
All predictive maintenance programs should include visual inspection as one of the
tools used to monitor plant systems. The cost—considered in conjunction with other
techniques that require periodic monitoring of plant equipment—is relatively small.
In most cases, visual inspection can take place as the predictive maintenance team
conducts the regular data acquisition required by any of the other techniques and there-
fore adds little or no costs to the program. Visual inspection can provide a wealth of
information about the operating condition of the plant. This simple but often neglected
tool can detect leaks, loose mountings, structural cracks, and several other failure
modes that can limit the plant’s performance.

Most of the commercially available vibration-monitoring systems provide visual
observation capabilities in their data acquisition instruments. Therefore, visual obser-