This standard specifies the conditions for carrying out fatigue tests under axial load on threaded fasteners. ISO 3800/II1) specifies methods for the statistical determination of fatigue strength. The specified tests are of the alternating voltage type, according to point 3.2.3 of ISO/R 373 (= UNI 3964) and are carried out at room temperature, in air, with the load applied along the longitudinal axis of the fastening element . These methods allow you to determine the fatigue strength of threaded fasteners in open joints (non-contacting mating parts), regardless of their application. Since the fastener causes variations in the results, minimum conditions are specified to reduce their effects. Alignment calibration control methods are provided.