Magnetic Memory Testing and Intensity Failure Analysis of Fractured Bolt of Cylinder Head on Hydrogen Gas Compressor

Abstract

Along with the wide application of pressure energy, large scale reciprocating compressor unit is becoming one of the necessary key equipments in petrochemical industry. The reciprocating compressor has complicated structure and it is very difficult to carry out measurement & analysis to the operation status of various components. Above all, as the most important fastener of the compressor, once fracture of cylinder head bolt of the reciprocating compressor occurs, major disaster will occur. Metal magnetic memory testing technology is a nondestructive examination technology based on magneto-mechanical effect principle. Specific change of leakage magnetic field will occur in stress & deformation concentrated region under combined action of alternate work load and geomagnetic field, macroscopic cracking can be detected and stress concentration and early state damage can be evaluated by utilizing this specific change, We carried out on-site examination on the fractured bolt of cylinder head of hydrogen gas compressor unit in refinery of certain petrochemical corporation with latest metal magnetic memory testing technology. On the basis of intensity analysis and dynamic load calculation to cylinder head bolt of the reciprocating compressor, we analyzed the cause of bolt fracture by using metal magnetic memory testing technology and drew out the magnetic memory signal distribution characteristics of the bolt and its fracture. We verified the correctness of testing result of the metal magnetic memory technology on cylinder head bolt and its fracture with metallographic examination technology; furthermore, we studied the reliability of bolt fatigue crack & fracture analysis and investigation of accident cause by using magnetic memory characteristic distribution signal.