Failure analysis on weld joint of centrifugal pump diffuser for oil and gas pipeline transportation. (October 2022)

• Record Type: Journal Article
• Authors: Mao, Liangjie; Gan, Lunke; Li, Wu; Zhang, Pengxiang
• Is Part Of: Engineering failure analysis. Volume 140(2022)
• Publication Date: 2022-10
• Subjects: Centrifugal pump diffuser -- EBSD pattern -- Misorientation -- Stress corrosion fatigue -- Oil and gas pipeline transportation; System failures (Engineering) -- Periodicals; Fracture mechanics -- Periodicals; Reliability (Engineering) -- Periodicals; Pannes -- Périodiques; Rupture, Mécanique de la -- Périodiques; Fiabilité -- Périodiques; Fracture mechanics; Reliability (Engineering); System failures (Engineering); Periodicals; Electronic journals; 620.112
• DOI: 10.1016/j.engfailanal.2022.106620
• Languages: English
• ISSNs: 1350-6307

Abstract

Highlights: The failure mechanism of centrifugal pump diffuser weld joint was analyzed by means of SEM, EDS and EBSD. The strength and toughness of weld joint, HAZ and matrix were quantitatively compared by geometrically necessary dislocation density. Welding defects such as slag inclusion and residual austenite reduce the corrosion resistance of diffuser weld joint. Some suggestions for improving the performance of diffuser and prolonging its service life are put forward. Abstract: The failure mechanism of weld joint in centrifugal pump diffuser was analyzed through scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and electron back-scattering diffraction (EBSD). Meanwhile, the strength and toughness of weld joint, heat-affected zone (HAZ), and matrix are quantitatively compared by geometrically necessary dislocation density ( ρ GND ). The result indicated that the strength and toughness of HAZ are the highest, followed by matrix, and weld joint is the lowest. Defects such as slag inclusion and residual austenite create initial conditions for the corrosion of weld joint. Severe chloride ion corrosion resulted in micro-cracks on the weld surface. Meanwhile, corrosion reduces the surface energy of the micro-cracks. Therefore, the concentrated driving force makes the micro-cracks with reduced surface energy spread rapidly, eventually causing the rapid failure of diffuser weld joint. This study may provide a reference for petroleum engineers and centrifugal pump manufacturers.