Cavitation erosion of polyethylene and chloroprene rubber for liners

Abstract

Resin lining is widely used as an anti-corrosion method for steel pipes. Since cavitation sometimes occurs near valves in piping system, it is necessary to consider not only the corrosion resistance but also the erosion resistance. The mechanical properties of the polymeric material change in various production methods, such as catalyst, density and mixing of the elastomer. However, few researches have been conducted from this point. In this paper, we examined the relationship between the mechanical properties and the erosion rate of a chloroprene rubber and a number of polyethylene materials produced by different methods. Power plants are operating for a long period. We examined the effect of aging by testing the aged material intended for usage in piping of power plant. We carried out the cavitation erosion tests by using a flowing apparatus as specified in the ASTM G134-95. Cavitation erosion of polyethylene occurred at 150 m/s or more. The flow velocity at 150 m/s and test time for 24hours is the appropriate experiment condition for cavitating liquid jet test of polyethylene. The maximum depth of erosion (MaxDER) of polyethylene decreases with the increase in tensile product and hardness. Among all the tested lining materials, the high density polyethylene (m-LLDPE-H) shows the best resistance to cavitation erosion in terms of MaxDE. The effect of aging on the erosion rate of polyethylene was small.