INVESTIGATION OF CORROSION RESISTANCE OF EQUIPMENT ELEMENTS USED IN FOOD PRODUCTION

Abstract

The results of corrosion studies conducted by gravity and polarization methods of samples of working parts of an electric pump used for pumping saline solution are presented. The purpose of the study was to determine the corrosion rate of grey cast iron parts and suggest either ways to increase their service life or find new solutions to the problem. Gravimetric and potentiometric methods were used to determine the corrosion rate. In both cases, a sodium chloride solution with a density of 1.2 g/cm³ was used as a corrosive medium. It is in this solution that the pump is operated. When conducting experiments using the gravimetric method, the exposure time was 0.5 hours, 1 hour, 1.5 hours, 2 hours and 2.5 hours. The average corrosion rate varied from 15–16 mm per year with low exposure from 0.5 to 1 h. Up to 8 mm per year at 2.5 h. The decrease in the corrosion rate is explained by the build-up of a shielding layer consisting of corrosion products on the surface of the samples. When conducting experiments using a potentiometric method using a PI-50-Pro potentiostat galvanostat, it was found that the corrosion rate is approximately 70 mm per year. Despite the difference in values, we believe that they are comparable. Using the potentiometric method, the corrosion rate is always higher than when using the gravimetric method, since corrosion products do not have time to form and affect the result. It has been established that the material used (grey cast iron) is unstable under these conditions and requires replacement. It is proposed to replace the pump with a centrifugal pump made of stainless steels.