Condition Monitoring

The ØDS Machinery Dynamics Group assists in condition monitoring by remote access and/or database transfer.

We have experience with identifying and solving machinery problems by using a number of commercially available condition monitoring systems.

• Centrifugal Compressors and Pumps
• Axial Compressors
• Gas or Steam Turbines
• Motors and Generators
• Turbo-Expander
• Reciprocating Machines
• Gears
• Feasibility Studies
• Customization
• Condition Based Maintenance
• Performance Mapping
• Diagnostics
• Balancing
• Troubleshooting

Condition Monitoring

Performance and Vibration Monitoring
Performance parameters can be used to evaluate if a machine does its job correctly and efficiently. Accordingly, variations in performance parameters can help to evaluate the state of the machine and thus assist in adequate maintenance.

Most machines will involve transmission of force through elements in motion. This
implies time dependence for direction and amplitude of reaction forces between machine elements. The time dependence of force, position, stress and strain implies vibrations for the machinery in operation.

Deterministic relationships between vibration and excitation exist for many phenomena in machinery dynamics, e.g. unbalance response of a single span rotor or forced torsional shaft vibrations in a drivetrain.

Vibration measurement is therefore a crucial part of any condition monitoring an diagnostic activity.

Feasibility
Several forcing mechanisms in machines have nondeterministic components, e.g. combustion noise, compressor surge or pump cavitation. Furthermore, even for deterministic machinery dynamic problems, vibrations will be contaminated by random noise from many sources, some originating from the measurement equipment itself.

Therefore, it is crucial to perform an evaluation of available condition monitoring strategies in each case, depending on machinery, process and environmental conditions.

• As part of the feasibility study, ØDS
  offers advice on
• alarm and trip levels
• best vibration analysis method for different failure modes
• run-up and coast-down settings
• optimization of data storage
• elimination of false alarms

Baseline Measurements
The benefits to be gained from vibration condition monitoring are greatly enhanced by careful baseline measurements and performance mapping.

Not only are the “as new” vibration and performance characteristics established. In addition, valuable system information is gathered to allow for design verification and optimization of the monitoring strategy.

Baseline measurements could be part of shop testing and commissioning. However, as the condition monitoring system may not be operational yet, and as most machinery problems arise in this phase, ØDS provides back-up vibration measurement services (up to 128 synchronized channels). Subsequently, the collected data can be incorporated in the condition monitoring database.

Troubleshooting
An important quality of a condition monitoring system is its ability to reduce data storage in a clever way. However, valuable transient data is typically lost when it comes to troubleshooting after a trip or failure.

Based on experience, it is possible to solve a number of trip and failure problems by interpretation of available condition monitoring data.

However, in some cases, it is necessary to have access to real time vibration and process signals with a high-frequency resolution.

ØDS therefore offers detailed vibration
and performance measurement as a
supplement to our condition monitoring
services.

Experience
The ØDS Machinery Dynamics Group consists of mechanical engineers who hold M.Sc. or Ph.D. degrees in rotor dynamics, fluid dynamics or solid mechanics.

ØDS’ assignments vary between in-depth
design verification studies, string test participation and on-site troubleshooting activities. We take pride in combining theoretical and practical knowledge of both components and machinery.

During the past 10 years, we have dealt with almost every thinkable turbomachinery problem. To name a few:

• Bearing and seal problems
• Rubs, looseness and other parametric excitations
• Rotating stall and trip transients
• Structural resonance in foundations