FAT / SAT Testing

Scenic Acoustic and Vibration Engineering Ltd (SAVE) are highly experienced in performing FAT (Factory Acceptance Test) and SAT (Site Acceptance Test) tests and Witness Testing. These tests include the assessment of the vibration response and other parameters, such as engine temperatures, bearing temperature, bearing lubrication pressures and flows, during the transient “run up”, “run down” and “steady state” running conditions of critical plant machinery.

An FAT is usually preformed at the vendor or nominated test facility prior to shipping to a client. The vendor tests the system in accordance with the clients approved test plans and specifications to show that the machine/system is acceptable to be installed and tested on site.

It’s an essential aspect of the whole system lifecycle and should be performed by experienced personnel. Time spent doing a proper FAT will lead to fewer problems when the equipment is installed on your site.

An SAT of the system is performed in accordance with client approved test plans and specifications to show the system is installed properly and interfaces with other systems and peripherals in its working environment.

In both cases, measurement results are assessed and quantified in accordance with the relevant ISO standards for the type of machine under test. These tests are often performed using Bode Plot and Nyquist Plot analysis to measure and assess rotor critical shaft speeds (critical frequencies), and shaft centreline plots and orbit plots for analysis of the shaft direction and precession and bearing clearances and stability.

FAT and SAT tests are usually performed on high speed machinery, whether it is new or existing overhauled plant machinery. FAT and SAT tests can be performed to assess the direct Rotor Dynamic response using non contact eddy current probes (proximity probes), and/or the vibration response of the machine casing using fixed accelerometers or velocity probes. Overall (Direct) and 1X Vibration amplitude and phase measurements are measured and quantified by comparison to a  Vibration Severity Chart. Acceptable tolerance range for new and overhauled machines are designated in Vibration Severity Zones A, and B respectively. Vibration amplitudes falling within Severity Zone C are not suitable for long term operation and those falling in Zone D are not acceptable.

FAT / SAT test also provide valuable rotor balance information such as eccentricity, which along with the rotor mass can be use to calculate the amount of Residual unbalance (U_res) in the rotor. This can then be compared to the Permissible Unbalance (U_per) values specified in the balancing standards, or to those specified by OEM’s and documented in the FAT / SAT test report.

Witness testing can be performed by SAVE to ensure that the equipment vendor carries out the factory acceptance tests in accordance with the specifications and other contract requirements.

FAT/SAT and witness testing is normally performed on new or existing overhauled critical high speed machinery such as Gas Turbines, Compressors, Steam Turbines, Power Generators. Vibration FAT tests are regularly performed during surge testing of centrifugal gas compressors. Vibration amplitudes are very sensitive to serge and axial thrust measurements can be monitored with proximity probes to ensure that the axial float of the shaft remains within specified tolerances. This will allow mitigating action to be taken before the compressor reaches a surge condition.