During operation, the discharge piping of an air compressor is often subjected to the combined effects of flow pulsations and mechanical transmission, resulting in vibrations of varying severity. Excessive vibration can lead not only to fatigue‑induced pipe rupture and joint leakage, but also pose safety risks to nearby equipment and structural elements. Therefore, understanding and adhering to applicable vibration‑level standards is essential for both engineering design and maintenance.
Vibration Value Standard Reference Framework
At present, in the industrial sector, vibration assessments of air compressors and piping systems typically rely on general‑purpose mechanical vibration standards and pressure piping design codes. Although specific limit values vary depending on operating conditions, the assessment framework is primarily based on the following criteria:
- Mechanical Vibration Intensity Standard: Usually for reference GB/T 6075 (equivalent to ISO 10816) series of standards. This standard is based on the root mean square value of vibration velocity (mm /s) as the primary evaluation metric, vibration intensity is classified into distinct zones—such as good, satisfactory, unsatisfactory, and shutdown—based on equipment type, power rating, and support stiffness, thereby assessing the operational condition of the equipment.
- Pipeline air velocity limitPipeline vibration is largely attributable to airflow pulsations. According to standard design codes for compressed air stations, maintaining an appropriately controlled gas velocity within the piping system is fundamental to vibration mitigation. Excessive flow velocities can generate aerodynamic noise and excitation forces; therefore, during design, the flow velocity must be rigorously calculated based on pipe diameter and operating pressure.
- Amplitude and Frequency ConstraintsWith regard to pipeline vibration, engineering practice typically assesses it by measuring the vibration displacement (amplitude). Under low-frequency pulsations, the pipeline’s amplitude is generally required to remain within a safety threshold to prevent fatigue failure caused by alternating stresses.
Vibration Measurement and Evaluation Methods
To accurately obtain the vibration values of the discharge pipeline, it is necessary to employ scientific measurement methods:
- Sensor placementMeasurement points should be located at positions most sensitive to vibration, such as near the air compressor’s exhaust port, pipe bends, tees, valves, and the mid‑span of straight pipe sections with large spans.
- Measurement parameters: Based on the vibration frequency, select appropriate measurement parameters. For low-frequency vibrations, displacement is typically measured; for medium- and high-frequency vibrations, velocity measurement is preferred.
- Operating Condition ConsiderationMeasurements shall be taken under full-load, steady-state operating conditions of the air compressor, with ambient temperature, pressure, and other relevant parameters recorded for comprehensive analysis.
Control and Vibration‑Mitigation Measures for Pipelines
When the vibration measurement of the outlet pipeline exceeds the specified allowable range, appropriate corrective measures shall be implemented promptly.
- Optimize pipeline routingAt the design stage, minimize the number of elbows and avoid sharp bends to reduce pulsation-induced impact forces during airflow redirection.
- Add buffer and damping devices.A receiver tank or a dedicated pulsation damper shall be installed between the air compressor outlet and the main pipeline to effectively absorb and attenuate the energy of airflow pulsations.
- Strengthen pipe supportsReasonably reduce the spacing between pipe supports and secure the piping with clamps equipped with vibration‑isolating pads. For pipe sections prone to resonance, install additional sway braces or adjust the support stiffness to avoid the resonant frequency.
- Adopt a flexible connectionAt equipment interfaces, use metallic flexible hoses or rubber expansion joints to provide a transition and isolate the transmission of mechanical vibration to the piping system.
Strictly adhering to vibration control standards for the air compressor discharge piping not only extends the service life of equipment and pipelines but also significantly reduces maintenance costs, ensuring the safe and reliable operation of the entire compressed air system.