Chapter 2 VIBRATION ANALYSIS APPLICATIONS

The use of vibration analysis is not restricted to predictive maintenance. This tech- nique is useful for diagnostic applications as well. Vibration monitoring and analysis are the primary diagnostic tools for most mechanical systems that are used to manu- facture products. When used properly, vibration data provide the means to maintain optimum operating conditions and efficiency of critical plant systems. Vibration anal- ysis can be used to evaluate fluid flow through pipes or vessels, to detect leaks, and to perform a variety of nondestructive testing functions that improve the reliability and performance of critical plant systems.

Some of the applications that are discussed briefly in this chapter are predictive main- tenance, acceptance testing, quality control, loose part detection, noise control, leak detection, aircraft engine analyzers, and machine design and engineering. Table 2.1 lists rotating, or centrifugal, and nonrotating equipment, machine-trains, and continu- ous processes typically monitored by vibration analysis.

Table 2.1 E ~ M and Procasa ~pica~ Mo.itorat by Wbration Analysis

CentHflqlal Reciprocating Continuous Proeess

Pumps Pumps Continuous casters Compressors Compressors Hot and cold strip lines Blowers Diesel engines Annealing lines Fans Gasoline engines Plating lines Motor/generators Cylinders Paper machines Ball mills Other machines Can manufacua~g lines Chillers PicHe lines

continued

4 Vibration Fundamentals

Table 2.1 Equipment and Processes I~ypimlly Monitored by ~ n Analysis

Product rolls Mixers ~ x e s Centrifuges Transmissions Turbines Generators Rotary dryers Electric motors All rotating machinery

Boring machines Hobbing machines Machining centers Temper mills Metal-working machines Rolling mills, and most machining equipment

Printing Dyeing and finishing Roofing manufacturing lines Chemical production lines Petroleum production lines Neoprene production lines Polyester production lines Nylon production lines Flooring production lines Continuous process lines

Source: integrated Systems, Inc.

PREDICTIVE MAINTENANCE

The fact that vibration profiles can be obtained for all machinery that has rotating or moving elements allows vibration-based analysis techniques to be used for predic- tive maintenance. Vibration analysis is one of several predictive maintenance tech- niques used to monitor and analyze critical machines, equipment, and systems in a typical plant. However, as indicated before, the use of vibration analysis to monitor rotating machinery to detect budding problems and to head off catastrophic failure is the dominant predictive maintenance technique used with maintenance management programs.

ACCEPTANCE TESTING

Vibration analysis is a proven means of verifying the actual performance versus design parameters of new mechanical, process, and manufacturing equipment. Preac- ceptance tests performed at the factory and immediately following installation can be used to ensure that new equipment performs at optimum efficiency and expected life- cycle cost. Design problems as well as possible damage during shipment or installa- tion can be corrected before long-term damage and/or unexpected costs occur.

QUALITY CONTROL

Production-line vibration checks are an effective method of ensuring product qual- ity where machine tools are involved. Such checks can provide advanced warning that the surface finish on parts is nearing the rejection level. On continuous pro- cess lines such as paper machines, steel-finishing lines, or rolling mills, vibration

Vibration Analysis Applications $

analysis can prevent abnormal oscillation of components that result in loss of product quality.

LOOSE OR FOREIGN PARTS DETECTION

Vibration analysis is useful as a diagnostic tool for locating loose or foreign objects in process lines or vessels. This technique has been used with great success by the nuclear power industry and it offers the same benefits to non-nuclear industries.

Nots:: CONTROL

Federal, state, and local regulations require serious attention be paid to noise levels within the plant. Vibration analysis can be used to isolate the source of noise gener- ated by plant equipment as well as background noises such as those generated by fluorescent lights and other less obvious sources. The ability to isolate the source of abnormal noises permits cost-effective corrective action.

LEAK DETEC11ON

Leaks in process vessels and devices such as valves are a serious problem in many industries. A variation of vibration monitoring and analysis can be used to detect leak- age and isolate its source. Leak-detection systems use an accelerometer attached to the exterior of a process pipe. This allows the vibration profile to be monitored in order to detect the unique frequencies generated by flow or leakage.

AIRCRAFT ENGINE ANALYZERS

Adaptations of vibration analysis techniques have been used for a variety of specialty instruments, in particular, portable and continuous aircraft engine analyzers. Vibration monitoring and analysis techniques are the basis of these analyzers, which are used for detecting excessive vibration in turboprop and jet engines. These instruments incorporate logic modules that use existing vibration data to evaluate the condition of the engine. Portable units have diagnostic capabilities that allow a mechanic to deter- mine the source of the problem while continuous sensors alert the pilot to any devia- tion from optimum operating condition.

MACHINE DESIGN AND ENGINEERING

Vibration data have become a critical part of the design and engineering of new machines and process systems. Data derived from similar or existing machinery can be extrapolated to form the basis of a preliminary design. Prototype testing of new machinery and systems allows these preliminary designs to be finalized, and the vibration data from the testing adds to the design database.