Failure Analysis of Inlet Pipeline of a Spray Cooler

Abstract

Corrosion perforation occurs frequently in oil field pipelines under strong oxidation environment. The causes for the failure of spray cooler after approximately 87,600 h in service have been investigated. To determine the failure mechanisms of pipes, material characterization and numerical analysis are conducted on the inlet pipeline. Ultrasonic thickness measurement is performed to check the corrosion rate and corrosion type of the pipe. Scanning electron microscopy is employed to observe the microscopic corrosion morphology of the pipeline. The microstructure of the corrosion products and the cause of corrosion are investigated using energy dispersive spectroscopy (EDS). Chemical composition and metallographic structure investigations are conducted to study the characteristics of the materials. Finite element analysis of the pipeline is employed to evaluate the deformation and stress distribution of the corrosion product film with a fluid–solid coupling model. Results of this investigation indicate that the reason of failure was the existence of strong oxidizing substances and the uneven distribution of corrosion rate that resulted from fluid accelerating corrosion.