This work aims to study the SN method and develop a model to obtain a result of damage accumulation in pressure vessels. Fatigue is a mechanical failure caused primarily by the application of loads that vary over time, whose main characteristic is the generation and/or the progressive growth of a crack. Fatigue fracture is a cumulative and localized process. The crack begins to appear in a critical region of the component, which in turn depends on a geometric detail in the locality. The fatigue life until its final phase is divided into two phases: the nucleation and crack growth phases. Crack initiation is caused primarily by the amplitude and value of the maximum stress, which depends heavily on geometric details, that is, the stress concentration factor. In this context, fatigue life is significantly affected by the range of maximum stress acting on the structure and together with these stresses the component carries a loading history, adding more and more data to its history, decreasing the component s useful life. With this in mind, rain-flow techniques implemented in the MATLAB software were adopted to improve damage calculations, since for a long loading history the calculations are not viable so it is preferable to make a model so that fatigue life projects are possible.