Analysis Of Vibration And Fatigue Strength Of Inlet Piping Of Ultra-high Pressure Reciprocating Compressor

Reciprocating compressors are often used to transport medium and high pressure gases,and play an important role in the petroleum,chemical,mining,and metallurgical industries.The vibration problem of the compressor inlet and outlet pipelines is widespread and harmful,it is very meaningful to conduct a comprehensive vibration and cracking analysis of the pipeline.In this paper,the mechanical properties of materials are obtained by experiments.And the strength analysis of the pipeline,the acoustic modal of the air column and the structural modal of the pipeline,Harmonic response analysis of pipeline,and the crack propagation life analysis of the pipeline are carried out.The pressure pulsation in the pipeline is calculated through FLUENT software.The main contents and conclusions are as follows:(1)The metallographic analysis and fracture analysis of the material show that the material meets the requirements of strength,and there are scallop lines and fatigue striations on the fracture surfaces with the characteristics of high-cycle fatigue crack propagation,which proves that the pipeline fracture is the fatigue fracture.Through tensile test and fatigue crack growth test,we get the elastic modulus of the material and fit Paris formula.(2)Through the acoustic modal analysis of the air column inside the pipeline and the structural modal analysis of the pipeline,it is shown that the pipeline will not have air column resonance and structural resonance.(3)Perform transient analysis on the fluid in the pipeline,and use UDF to compile and load the pipeline outlet mass flow rate curve.The results show that the pressure unevenness of the compressor end of the pipeline is 8.55%,which exceeds the API618 limit of 7%.(4)The harmonic response analysis of the pipeline shows that at the compressor excitation frequency,the peak-to-peak amplitude of the pipeline in the X direction is 0.069mm,and the peak-to-peak amplitude in the Y direction is 0.017mm,which does not exceed the pipeline according to the API618 standard 7.9.4.2.5.2.4 Design vibration criterion a The he specified allowable peak-to-peak amplitude is 0.5mm.(5)Using the method of fracture mechanics to calculate the propagation life of the pipeline surface crack,the propagation life from the initial 0.1mm deep surface crack to maxmium crack length 17.86mm is 6.8 years.The crack propagation life decreases with the decrease of pipe-clamp stiffness.Through the research on the influence of the position and number of the pipe-clamps on the vibration of the pipeline,the best positions of the three pipe-clamps are found to reduce the vibration of the pipeline in the X direction by 85.36%and to reduce the vibration of the pipeline in the Y direction by 54.8%.