A method is proposed for determining the strength of a metal shell structure under mechanical loading and prolonged contact with an aggressive hydrogen-containing medium. The mechanical properties of the structural material change under the influence of such media. Steels exhibit a decrease in ductility, which is called hydrogen embrittlement. This effect must be taken into account when assessing the strength of steel structures operating in contact with hydrogen-containing media. The method is illustrated with an example of a steel cylindrical pipe in contact with a hydrogen sulfide-containing medium. Data obtained in the course of an earlier experiment are used to determine the mechanical parameters of the pipe material. The possibility of determining the mechanical parameters beyond the saturation time of the samples in the experiment is shown.