The influence of gaseous hydrogen on crack growth in structure steels is analysed taking into account the thermal influences and effects of hydrogenation-degasation of metals. The same material under various external conditions (temperature, pressure, stresses, etc.) can display sensitivity to different kinds of hydrogen degradation. The forms of realization of hydrogen degradation are diverse and can appear unexpectedly. This degradation happens during the operational cycles of a structure, in the form of cracks of hydrogen embrittlement, but can also appear during the shutdown of the unit, in the form of hydrogen destruction formation. The physico-mechanical model for evaluation of internal hydrogen defects growth kinetics with the account for non-stationary thermal influences is proposed. The example of durability estimation for the case of the hydrocracking reactor of petroleum is given.