Hammer Peening is the process of cold working of metal surfaces to create residual compressive stresses to improve material properties by mechanical means. By creating residual compressive stresses into the surface zone, the dynamic stress cracking and corrosion resistance of high alloy steels is significantly improved and the fatigue strength is increased. The equipment itself consists of a steel body of a certain diameter with installed pistons and a fitting for connecting to compressed air. The compressed air acts on the piston, during the movement of which it moves into the processing area (work hardening). The piston at the tip has a tungsten carbide insert to increase the tool life in the process of vibration (reciprocating) action on the inner surface of the pipe.