New tools for PdM

March 15, 2006
Learn about condition monitoring beyond oil analysis, temperature and vibration in Sheila Kennedy's monthly Technology Toolbox column.

Getting the most out of installed assets will become more difficult as baby boomers retire. Their unique skillsets and hands-on experience will be hard to replace. One way to minimize this organizational strain is by monitoring the mechanical stress on your machines.

New ultrasonic techniques for condition monitoring make it possible to “hear” friction and stress in rotating machinery, which can predict deterioration earlier than conventional techniques. Condition monitoring, coupled with strategic data integration, help to automate critical processes that influence total plant health.

Ultrasonic condition monitoring: Ultrasonic technology is sensitive to high-frequency sounds that are inaudible to the human ear, and distinguishes them from lower-frequency sounds and mechanical vibration. Machine friction and stress waves produce distinctive sounds in the upper ultrasonic range.
Changes in these friction and stress waves can suggest deteriorating conditions much earlier than technologies such as vibration or oil analysis. With proper ultrasonic measurement and analysis, it’s possible to differentiate normal wear from abnormal wear, physical damage, imbalance conditions and lubrication problems based on a direct relationship between asset and operating conditions.

Among the machine process measurements that can be gauged are speed/rpm, head pressure, weight, and a valve’s position. Ultrasonic sensors that are integrated with condition monitoring software can produce alarms or e-mail notifications when thresholds are exceeded, and trigger maintenance activity.

“The time [remaining] before potential failure can be relatively short,” says Wil Chin, director of field systems for ARC Advisory Group. “With ultrasonics, you can pick up very minute problems manifested by changes in friction, giving maintenance and operations more time to deal with an issue before it shuts down a line or plant.”

Ultrasonic technology also can be used to establish optimal operating parameters, thereby extending asset life. For example, when stress levels are correlated with operating load, it’s possible to identify the rotational speed that generates the least amount of stress on an engine. In a centrifugal pump application, ultrasonic technology can identify cavitation and allow operators to adjust the pump speed and process parameters to reduce detrimental effects on the pump and surrounding equipment. 

An additional benefit of ultrasonic technology is the ability to better manage just in time (JIT) inventory. One steel company saved almost $3 million in inventory using a solution from Swantech that provided significant advance warning of possible deterioration within their assets.

Stress wave analysis: “Friction is always present in any machine,” explains Ralph Genesi, president and CEO of Swantech. “Our ultrasonic Stress Wave Analysis (SWAN) technology quantifies this friction and then tracks it as it changes over time with variable loading conditions.”

For example, Swantech’s condition monitoring solution detects minor damage in its earliest stage, and helps to isolate the specific components and location of the components involved. The system calculates the extent of the damage and rate of progression so that maintenance can be scheduled accordingly.

“Swantech is the first to combine ultrasonic sensor technology into a condition monitoring software package,” Chin adds. “The data doesn’t have to be analyzed by a reliability engineer to determine the problem, because the software’s analysis engine recommends the potential cause.”

Integration with maintenance: Condition monitoring systems and smart sensors are becoming increasingly sophisticated, less expensive and more prevalent in the plant environment. User-friendly alternatives are replacing tools that once required specialized skills to operate. Data can now be gathered, analyzed and presented in an actionable format in real time. However, the diversity of condition monitoring methods and devices can impose its own burden.

“Automation suppliers are in the catbird seat, central to all plant information, but without touchpoints to the rest of the equipment or the solution itself,” says Chin. To overcome this issue, automation companies like Invensys and Rockwell Automation are developing or acquiring condition-monitoring technology. “The objective is to compile all data for the operator to view from a single interface – one screen for asset health and another for control.”

To expedite predictive maintenance tasks, condition monitoring suppliers are developing interfaces to enterprise asset management systems so that work orders, inventory requests and associated processes can be activated automatically.

Swantech’s condition monitoring technology is being incorporated into the Invensys Asset Performance Management (APM) solutions under the Invensys name. Integration with Invensys’ Avantis maintenance management software will be available. Swantech is also being integrated with the Indus Asset Suite.

E-mail Contributing Editor Sheila Kennedy, managing director of Additive Communications, at [email protected].

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