Experimental and computational failure analysis of a high pressure regulating valve in a chemical plant

Abstract A high pressure regulating valve for producing ethylene vinyl acetate copolymer in a chemical plant failed after three years in service. The failure analysis of valve was performed by means of visual inspection, stereo microscopy, optical microscopy, scanning electron microscopy and computational fluid dynamics (CFD). The morphology analyses showed that the craters on the valve plug and cage, especially the end of the valve plug, were mainly caused by cavitation erosion, and the ditch damage resulted from the erosion due to impingement and scouring of the high velocity flow. The corrosivity of vinyl acetate was proved to have few effects on the materials damage. The failure reasons were further demonstrated by the simulation results, which presented the distribution of the sites suffering the high velocity flow erosion and possible cavitation erosion. The computed numerical results showed a good agreement with morphology analyses.