Abstract: The invention concerns a method for determining a mechanical stress of a runner (40), of a hydraulic machine (10), wherein the runner is arranged to rotate around a rotation axis, wherein the hydraulic machine comprises a hydraulic channel delimited by hydraulic surfaces of the runner, the hydraulic surfaces being the surfaces against which a stream of water exerts the forces when the runner is driven in rotation by said stream of water, wherein the runner further comprises a sensor (G) on protected areas positioned away from the hydraulic channel, the method comprises the steps of: a) collecting a physical quantity measured by the sensor (G), b) determining a mechanical stress on a specific location of the hydraulic surface, via a transfer function that correlates the physical quantity measured in step a) and said mechanical stress on the specific location.

Abstract: The invention concerns a method for detecting a fatigue undergone on at least one specific location of a hydraulic unit (10), the method being characterized in that the fatigue undergone on the at least on specific location is detected by at least one fatigue indicator (F) said at least one fatigue indicator arranged for being remotely queried via wirings or via a wireless connection.

Abstract: The present application describes a method for welding two parts to each other. The two parts are made from steel having a high thermomechanical yield strength. The welding method includes a welding step in which a weld bead is created inducing a heat-affected zone to appear. The method also includes a heat treatment step having a heating step, during which at least one portion of the weld bead and the HAZ is gradually heated to a treatment temperature; then a holding step in which the portion of the weld bead and the HAZ is kept at the treatment temperature; then a cooling step in which the HAZ and the weld bead are gradually cooled and pass from the austenitic transformation end temperature to the martensitic transformation end temperature of the steel of the parts in a time between 7.5 s and 8.5 s, and pass from the austenitic transformation end temperature to the martensitic transformation end temperature in a time shorter than 15.5 s.