Evaluation of hydro abrasive wear in different alloys of submersible centrifugal impellers used in sewage pumping in pumping stations

ABSTRACT

Premature losses due to hydroabrasive wear occur in the impellers of submersible centrifugal pumps installed in sewage lift stations, reducing hydraulic efficiency and increasing energy consumption. The purpose of this study is to contribute to the best choice of material, minimizing losses from hydroabrasive wear of super duplex stainless steel alloys, tempered gray cast iron and high chromium white cast iron, commonly used in pumps. In addition, the macrosurface aspect of the samples after the hydroabrasive test was analyzed. The hydroabrasive wear tests were performed in a 10:1 solution of water and silica sand at two speeds of 5.2 m/s and 7.1 m/s. The tests were run on a hydroabrasive machine for 216 hours, with mass loss measurements taken at 24-hour intervals. The high chromium white cast iron had the lowest mass loss due to wear. Furthermore, the test speed of 7.1 m/s resulted in greater mass losses in the studied alloys than the test speed of 5.2 m/s. The mass losses due to hydroabrasive wear of the alloys investigated were linked to hardness, microstructural characteristics, and the morphology of the worn surfaces. These factors were used to describe the results and justify the best and worst performance of the alloys investigated. Therefore, the high chromium cast iron (FBACr) showed the best performance due to its high hardness resulting from its microstructural characteristics (matrix and M₇C₃), and its worn surface morphology that presents a shiny and polished aspect with less craters and grooves than the other studied alloys.

Keywords
Hydroabrasive Wear; Pumps; Impellers; Sewage Elevators