Air compressor piping is very prone to vibration, which is an inevitable problem caused by its working principle. Severe air compressor piping vibration and its consequences threaten the safe production of equipment. Therefore, studying the status and causes of air compressor piping vibration and effectively reducing it is of great significance to safe production.

Importance of air compressor piping

Air compressor is an important engineering fluid machinery and is widely used in industrial enterprises. With the rapid development of petrochemical industry, large piston air compressors are especially widely used in refining, fertilizer, coal chemical and other enterprises.

‌The air compressor piping serves as a “bridge” between the air compressor and the gas-using equipment. It not only ensures the safe and efficient transmission of compressed air, but also directly affects the stability and efficiency of the production process.

The following is the importance of air compressor pipings and the impact of air compressor piping problems:

‌Transmitting compressed air‌: The primary function of the air compressor piping is to transport the compressed air generated by the air compressor to various gas-using equipment to ensure the normal progress of the production process‌.

‌Ensure stable air pressure‌: A reasonably designed air compressor piping can reduce the pressure loss of compressed air during the transmission process and maintain a stable air pressure, thereby ensuring the normal operation and production quality of gas-using equipment‌.

‌Separation of condensed water and impurities‌: Air compressor water separators are usually set up in the pipeline to separate condensed water and impurities in the compressed air to prevent them from entering the gas-using equipment and affecting the performance and life of the equipment‌.

‌Flexible layout‌: The air compressor pipeline can be flexibly arranged according to the actual situation of the production site to meet the gas demand of different equipment and improve production efficiency‌.

air compressor piping vibration is a common problem in compressed air systems and has received more and more attention. Severe pipeline vibration and its consequences threaten the safe production of the device.

The alternating stress generated by the vibration of the air compressor pipeline will cause fatigue damage to the pipeline; the displacement caused by the vibration will cause the loosening and wear of the connectors, causing the pipeline to loosen and fall off the frame.

In severe cases, the pipeline may even tear, causing leakage, combustion, explosion and other serious secondary disasters.

Therefore, studying the status and causes of air compressor piping vibration and effectively preventing and reducing it is of great significance to safe production.

Causes of air compressor piping vibration

The vibration of air compressor piping is mainly caused by air flow pulsation. Due to its own structural form, except turbo compressors, the air compressor’s suction and exhaust air flow has the characteristics of periodic and intermittent changes, which inevitably causes the gas in the system pipeline to pulsate.

When the pulsating air flow is transported along the pipeline, it will generate a changing exciting force. Under the influence of this exciting force, the air piping produces a mechanical response. The greater the pressure pulsation, the greater the vibration response of the pipeline.

The vibration generated on the air compressor piping is also related to the vibration generated by the air compressor itself. Excessive vibration of the motor during the operation of the air compressor will cause fatigue cracking of the other air compressor parts such as the welds of the pipeline and the pipe, the pipe seat, the drain pipe, the connecting wire, the signal wire, the temperature and pressure measuring points, etc., resulting in leakage.

If it is operated unsafely for a long time, it will pose a threat to the air piping and related equipment. In severe cases, the unit will cause the pipe to break due to excessive vibration.

Air compressor piping vibration damping measures

When there is obvious vibration in the air compressor piping, the pipeline should be visually inspected in time to record the time, frequency, vibration value, whether the support and hanging parts and the pipeline are damaged and failed, whether the pipeline is deformed, etc.

Analyze the cause of vibration and take corresponding measures. It should be noted that rigid constraints should be avoided as much as possible to fix the pipeline to avoid transferring vibration to the inside and causing damage. There are four common pipeline vibration reduction methods:

Set orifice plates at specific locations

The orifice plate is a resistance element. When the air flow passes through the orifice plate, energy loss will occur, thereby reducing the air flow pulsation. Orifice plates of different sizes correspond to different local loss coefficients. For air compressor pipelines, the orifice plate is generally set at a position with greater pulsation.

When selecting an orifice plate, the thickness, aperture, and material of the orifice plate should be considered as important factors to avoid additional problems such as gas interception, orifice plate damage or corrosion after installation.

Optimize the layout or size of the air compressor piping

When designing the air compressor, the air flow pulsation under different working conditions should be fully considered. Especially today when the stepless air volume adjustment system is widely used, the influence of different air volumes on the vibration of the compressor unit and pipeline should be calculated.

When calculating the pipeline vibration mode, the air column frequency should be avoided as much as possible within its natural frequency range.

In addition, due to the high strength of standard pipe fittings themselves, the main process pipelines of the compressor should use standard pipe fittings as much as possible. For instrument pipes, tees and other locations where standard pipe fittings cannot be used, appropriate reinforcement measures should be taken.

Reasonable setting of air compressor piping support

Common air compressor piping supports are divided into sliding brackets, fixed brackets and guide brackets according to their uses. Their design and construction should meet the requirements of relevant standards and specifications. Pipeline supports should use independent foundations as much as possible, and avoid being set on the structural beams of the frame and plant to prevent resonance.

In addition, the pipeline supports need to be arranged at unequal intervals, and the difference is generally 100~200mm. The distance between the two brackets is generally not more than 3m, and anti-vibration pipe clamps should be set on the brackets. In addition, it is strictly forbidden to reinforce the pipeline by rigid constraints to avoid stress concentration and local tearing.

Use damping shock absorber

The damping shock absorber is to reduce vibration by converting the kinetic energy of the air compressor piping vibration into the thermal energy of the damping fluid. The damping response is fast, there is no time delay, the damping fluid has stable performance and long life, and it is an effective flexible vibration reduction device.

Its characteristics are that it can produce damping and vibration reduction effects on all degrees of freedom of the air compressor piping, produce greater damping for impact loads, and also produce damping effects for small vibrations.

Conclusion

According to the working characteristics of air compressors, air piping vibration is inevitable. It is strictly forbidden to use “simple and crude” methods such as forced rigid constraints to isolate and eliminate vibration. Generally speaking, air flow pulsation is the internal cause of air compressor pipeline vibration, and the structure of the pipeline is the condition that causes vibration.

Through testing, analysis and calculation, using appropriate methods to reduce vibration and make the air compressor piping reach the ideal working condition is of great significance to the safe operation of the compressor unit and compressed air system.

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