Repair of centrifugal pump working wheel made of zirconium

Abstract

Zirconium and zirconium alloys have their main application in the chemical industry as a corrosion resistant construction material, since it shows excellent resistance in most aggressive environments such as organic and inorganic acids, salt solutions, strong alkalis and some molten salts. Some of the more important pieces of equipment in the chemical process industry where zirconium and its alloys are used include evaporators, tanks, reactor vessels, pumps, valves and piping. Considering the importance and high cost of such parts, repair welding occupies a significant place in maintaining such equipment. This paper presents the technology of repair welding of the centrifugal pump working wheel in the plant for the production of acetic acid. It is made of cast zirconium alloy Zr 702. Within the framework of the research, an analysis of the basic and filler material for the repair welding process was performed, and welding parameters and conditions were defined. In order to verify the proposed technology, trial welding was performed and based on the good results obtained, repair welding of the working wheel of the centrifugal pump was performed. The quality of the performed repair was checked by visual control and penetrant control, and it was found that the surfaced layer meets the quality level according to the SPRS EN ISO 5817 "B" standard. The fact that the repaired working wheel has been in the production process for 8 years, is a proof of welldefined technology and successfully performed repairs.