Elevation of the Fatigue Strength of Pump Rods as a Result of Treatment with a Special Medium

We analyze the causes of the in-service loss of integrity of the steel rods of pumps due to the fatigue fracture of their main part as a result of propagation of the surface cracks. To increase the service life of the rods, it is proposed to use a special liquid working medium inhibiting the process of propagation of fatigue cracks as a result of the artificial creation of the effect of crack closure. As a result of scaled-down experiments on the high-cycle fatigue of rods made of 35KhM and 20N2M steels performed after long periods of operation, it was discovered that, on the one hand, a 3% NaCl solution exerts a noticeable negative influence on the fatigue strength and, on the other hand, the working medium exerts a significant positive effect. This effect manifests itself in the increase in the fatigue strength of the rods not only in corrosive media but also in air. For the practical realization of the method under the field conditions, we propose a design of a special chamber, which is fixed on the rod and covers its part.