Seeking help regarding excessive vibration in a reciprocating compressor
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Our company’s 3 4M-type compressors are new; during the commissioning process, the foundation of each compressor vibrated strongly, causing the surrounding ground to vibrate as well. Could anyone tell me what the cause of this is?
All 3 units are fully vibratory and are new machines, so the possibility of assembly defects in the equipment itself is low. It is recommended to start with installation, piping, and foundation quality; if possible, it is also useful to identify the type of vibration first, as this helps in making judgments.
It’s very likely that there’s an issue with the foundation
Personally, I think it’s a problem with the installation, such as misalignment of the couplings. The foundation is usually grouted as a whole, and there are generally no problems; vibrations can only be traced to the unit itself. The characteristic of reciprocating machines in compressing gas is that they generate strong pulses, which cause vibration in the connected pipes and auxiliary equipment. As a result of uneven stress distribution, these vibrations are transmitted back to the machine through the pipes, leading to excessive oscillation of the cylinders; however, this generally does not cause overall vibration of the foundation.
There should be no major issues with the device itself; it is recommended to look for the cause in the design and installation
During testing, I first opened the air valves of all 4 cylinders to carry out running-in; at that time the basic vibration was very severe (this was the case with both new units). It seems this has little to do with the piping installation. After closing the air valves again and attempting to start the machines without load, the basic vibration on the ground remained high, and it could be felt up to 100 meters away. After consulting them, the manufacturer said it was due to resonance between the foundation and the equipment, and suggested increasing the size of the foundation.
If it vibrates even under no load, it is indeed possible that resonance is the cause, and the foundation needs to be reinforced. When testing the two new reciprocating machines we have here, the air valves and valve covers were not installed; instead, wire mesh was used to cover them in order to prevent foreign objects from getting in
If the stiffness of the foundation of a reciprocating compressor is insufficient, gas pulsations will occur and the vibrations will be severe. In addition to increasing the foundation’s stiffness, it is possible to install a large outlet buffer tank to mitigate these gas pulsations.
I suggest you check the civil engineering drawings to see the dimensional parameters for foundation grouting. Typically, the base of the compressor does not extend much beyond the footprint of the unit itself. Unless the foundation is insufficient during construction, resonance generally does not occur. Also, what is the compression level of your 4M machine? Are there tandem cylinders?
1. Who is responsible for inspecting the foundation? 2. Check who installed it and examine the installation data. 3. Check compressor pipeline stress and suspension. 4. How is this supervisor doing their job?