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VIBRATION ANALYSIS

Vibration Analysis is a predictive maintenance method which allows early problem detection in rotating machinery, such as: Turbines, Engines, generators, mills, gearboxes, fans, shafts, motors, compressors, chillers, pumps, mixers, and driers - in fact, almost any type of active machinery.

Vibration analysis consists in listening inside the machine. Each component vibrates differently and generates a characteristic noise that leaves a typical fingerprint in the spectrum in the form of a linear pattern. If damage is present, the pattern stands out from the noise floor. This allows the specialist to recognize, for example, whether the problem comes from unbalance, misalignment or bearing damage. In addition to an accurate diagnosis it is generally also possible to determine whether urgent action is necessary or whether it can wait until the next scheduled servicing.

Vibration Analysis will identify component faults - such as defective bearings, Imbalance & misalignment and other defects which enable you to take maintenance action before a failure in service brings your plant to a halt.

Vibration analysis - The benefits

The bottom line is that vibration analysis benefits both the operator and the maintenance technician:

  • Enables the identification of machine faults
  • Provides information on root causes
  • Localizes the affected components
  • Optimizes spare parts logistics
  • Allows early planning of maintenance measures.

Our engineers and technicians will provide both routine and complex vibration condition monitoring services in an effective and useful manner to the clients.

FREQUENCY ANALYSIS

Each waveform consists of contributions from individual vibrating parts usually having different frequencies.

Frequency analysis is a tool that is capable to identify these individual contributions directly. Frequency analysis is performed by fouriertransform (by its decomposition into fourier series.)

Methods and signal forms in vibration analysis

  • FFT analysis: often used for detecting the most common machine faults, such as misalignment or unbalance.
  • Order analysis: Variant of FFT analysis used for machines with variable RPM; instead of the frequency, the multiple of the rotational speed (order) is analyzed in the spectrum;
  • Envelope analysis: used for diagnosis of damaged gear toothing and roller bearings.
  • Cepstrum: facilitates the diagnosis of gear and bearing damage.
  • Time waveform: suitable for analysis of the measured signal and for detecting beats and transients (random pulses).
  • Orbit: used for analysis of shaft vibrations – especially in shafts with sleeve bearings.
  • Phase measurement: used together with the FFT analysis to differentiate machine faults, such as unbalance, misalignment or loose parts.
  • Resonance analyses: for identification of natural frequencies and natural vibrations in a machine or structure. Methods include impact tests, recording of the run-up and coast-down curve and measurement of the shaft bending lines.

Most mechanical faults with rotating equipment induce vibration i.e., unbalance, misalignment, looseness caused by poor assembly, deterioration of bearings, wear of gear teeth, etc. Vibration monitoring involves the periodic measurement of machine vibration, usually measured on bearing housings or from the machine supervisor's panel output/data.

Vibration monitoring can detect a wide range of failure modes:

  • Bearing defects
  • Misalignment
  • Imbalance
  • Bend shaft
  • Soft Foot Mounting
  • Mechanical Looseness
  • Resonance
  • Bearing pre-load and incorrect assembly
  • Gear mesh abnormalities
  • Journal bearing faults
  • Belt drive faults
  • Pump cavitation and process flow problems
  • Beat frequencies
  • Electrical faults like rotor bar damage

Instruments

VIBXPERT II is an all-in-one data collector, vibration analyzer and field balancer based on latest technology.

  • Fastest measurements using trending spectra
  • User-friendly and intuitive operation
  • Powerful analysis and diagnostic tools for machine trouble shooting
  • Automatic switchbox support
  • Long-lived battery

VibXpert II Field balancer for In situ dynamic balancing

  • ATEX zone 1 rated
  • Intuitive joystick operation (left and right handed)
  • Fast data collection with "trending spectra"
  • Rugged aluminum housing
  • Compatible with VIBCODE sensor
  • Highest resolution for in-depth analysis
  • Interface to protection systems for additional analysis

VIBXPERT EX vibration analyzer for the use in explosive environments

  • ATEX zone 1 rated
  • Intuitive joystick operation (left and right handed)
  • Fast data collection with "trending spectra"
  • Rugged aluminum housing
  • Compatible with VIBCODE sensor
  • Highest resolution for in-depth analysis
  • Interface to protection systems for additional analysis

Software Ominitrend

The perfect software tool for vibration analysts

  • Powerful analysis tools for effective diagnosis of machinery health
  • Powerful customizable reporting
  • Data exchange with Computerized Maintenance Management Systems (CMMS)
  • Easy graphical machine set up
  • Multiple standard machine templates
  • Central task and route configuration
  • Clear overview and status display of the monitored assets
  • Practical analysis tools

STRUCTURAL DYNAMIC ANALYSIS

When the frequency content of a dynamic loading and the natural frequencies of a structure are in the same range, then this approximation is no longer valid. This is the case for most machinery (compressors, pumps, engines, etc.) which produce loadings whose frequency content overlaps the natural frequencies of the structure on which they are mounted (platform, FPSO, etc.). In such a case, only a dynamic analysis will accurately predict the amplification of the response of the structure. Such loadings cannot be replaced by quasi-static equivalents.

What makes these analyses even more challenging is the fact that the machinery, its equipment and the mounting skid cannot be seen as black boxes. They will interact with the foundation, the platform or the FPSO and the only way to know the magnitude of this interaction is to conduct a structural dynamic analysis that includes the foundation. This is a critical consideration which when overlooked considerably reduces the reliability of the machine and might even cause safety concerns.

Benefits of Structural analysis

  • Compute natural frequencies of simple and complex structures
  • Compute structural response to dynamic loads
  • Compute structural response to base excitations (for example earthquakes)
  • Design vibration absorbers (tuned-mass dampers)
  • Design vibration isolators
  • Design foundations for rotating equipment
  • Troubleshoot and modify existing structures to reduce unacceptable levels of vibration

Structural vibration occurs when dynamic forces generated by compressors, pumps, and engines cause the deck beams to vibrate. This vibration leads to piping failures, poor equipment reliability, and safety concerns. The vibration is due to the structure being mechanically resonant. The term “resonance” occurs when dynamic forces coincide with the natural frequencies of the supporting structure. At resonance, the forces are amplified up to 20 times, and cause deck beams to vibrate above safe operating limits.

TORSIONAL VIBRATION

Torsional vibration is angular vibration of an object commonly a shaft along its axis of rotation. Torsional vibration is often a concern in power transmission systems using rotating shafts or couplings where it can cause failures if not controlled. A second effect of torsional vibrations applies to passenger cars. Torsional vibrations can lead to seat vibrations or noise at certain speeds. Both reduce the comfort.

The purpose of TVA is to analyze torsional vibration characteristics (i.e. dynamic torque, stress and angular distortion) of drive-coupling-compressor system under alternating compressor (and driver) torques, select an appropriate coupling, identify and solve potential torsional vibration problems, and avoid damage of compressor shafts, engine shafts, motor shafts, couplings and associated compressor oil pumps and motor fans.

TVA begins by simplifying the drive-coupling-compressor physical model into a mathematical analysis model with multiple disks with moment of inertia and connection stiffness between them. This facilitates the torsional force dynamic response analysis.

Sources of Torsional vibration

  • Internal combustion engine: The torsional vibrations of the not continuous combustion and the crank shaft geometry itself cause torsional vibrations
  • Reciprocating compressor: The pistons experience discontinuous forces from the compression.
  • Universal joint: The geometry of these joint causes torsional vibrations if the shafts are not parallel.
  • Stick slip: During the engagement of a friction element, stick slip situations create torsional vibrations.
  • Lash: Drive train lash can cause torsional vibrations if the direction of rotation is changed or if the flow of power, i.e. driver vs. driven, is reversed.

LASER ALIGNMENT

It is proved fact that 50% of machinery failures, including motors failures are due to "Misalignment" of machines. This is the area, which is commonly neglected in many industries; one major reason is that it is difficult and time consuming to perform, often requiring specialist skills to align all machinery accurately. To overcome these problems adaption of Laser alignment technique is most effective solution. All the rotating equipment including high speed turbines, compressors, pumps, fans etc. can be aligned effectively by using our specialized Rotalign laser alignment Kit.

Machines operating in perfect alignment run at their most efficient. Misaligned shafts are recognized as one of the greatest contributors to plant breakdowns, due to the increased forces placed on bearing, mechanical seals, internal components and motor drives.

Rotating machines are prone to misalignment. Correctly aligned and regularly controlled machines significantly reduce operating and maintenance costs. Conventional methods for shaft alignment, such as straightedge, thickness gage or dial gage, are very time consuming. The quality of the results also highly depends on the experience of the operator.

Our laser measuring devices use unique state-of-the-art technology to ensure maximum precision and user-friendly alignment of shafts.

LASER ALIGNMENT DEVICE

ROTALIGN Ultra iS is a highly versatile system made to handle alignment on all types of rotating machines. This best-of-breed laser alignment system will save you a lot of time and effort!

Precise alignment pays off in many ways:

  • Reduce power consumption
  • Decrease wear on bearings, seals, shafts and couplings
  • Avoid overheating of bearings and couplings
  • Reduce vibrations in shafts and foundation bolts
  • Significantly reduce damage to shafts and foundation bolts.