Selection of Predictive Maintenance Techniques - Continued

DOE-STD-1052-93

Grease analyses are techniques used to detect changes in

lubrication properties of grease. Sensory tests such as color,

odor, and consistency are most often applied to greases. A

penetration test is sometimes used to quantify grease

consistency. Grease analyses are often performed on samples

obtained from motor-operated valves.

Bearing Temperature Trending/Analysis - a technique used to

measure and trend temperatures of critical machinery bearings to

predict failure - Changes in bearing temperature may indicate wear

due to loss of lubrication, excessive vibration, or intrusion of foreign

material into the rotating assemblies. Bearing temperature analysis

is often performed in conjunction with the vibration monitoring and

lubricating oil analysis/ferrography programs.

Infrared Thermography - a technique based on the fact that the

infrared radiation emitted by a source varies with its surface

temperature - Infrared surveys may be performed on heat -

producing equipment such as motors, circuit breakers, batteries,

load centers, and insulated areas to monitor for high resistance,

loose connections, or insulation breakdown. Additionally, this

technique may be applied to pinpoint condenser air in-leakage

locations and valve leaks.

Acoustical/Ultrasonic Testing - a technique used to measure

acoustical emissions from components such as valves and heat

exchangers - This technique is used to monitor valves for leakage

and heat exchangers for proper flow rates. In addition, ultrasonic

testing may detect weld crack propagation and check for piping

erosion/corrosion effects.

Motor-operated Valve Testing - a technique used to measure and

analyze key motor-operator parameters such as running current,

voltage, stem thrust, limit and torque switch set-points, and valve

stroke times - This technique is extensively used to provide accurate

indication that the motor-operated valve operates as designed under

actual system conditions of temperature, flow, and pressure.

Motor-operated valve testing is also used to trend performance to

identify degrading conditions.