Failure analysis of the blackwater regulating valve in the coal chemical industry

Valves' failure is common in the coal industry due to their severe working conditions, like highvelocity erosion, cavitation erosion, and so on. The damage morphologies of the blackwater regulating valve (BRV) in coal chemical equipment were investigated by stereo microscopy, metallographic microscopy, and scanning electron microscopy (SEM). Failure causes of the valve were analyzed from the material structure, hole defects, composition, hardness of the material, corrosive media, and computational fluid dynamics (CFD). The results showed the damage on the valve spool and seat was attributed to the combined effect of slurry erosion, cavitation erosion, and corrosion. The soft cobalt phase was preferentially removed followed by the pulling-off of WC particles, which is the failure mechanism of BRV.