An original simplified procedure to estimate the remaining service time of corroded shell of an on-the-ground steel tank used to store liquid fuels is presented in this paper. Current corrosion progress trend, identified a’posteriori based on the obligatory technical condition monitoring, is extrapolated to the future tank service time under the assumption that the conditions of service would not change and no renovation or modernization works would be undertaken. Failure probability understood as exhaustion of the capability to safely resist the loads applied due to the corrosion progress constitutes the measure of the sought uptime. For comparative purposes several effective inference methods have been proposed for the same input data, based on formally qualitatively different but corresponding description measures. It has been shown, that in the analysis of this type the representative values, usually expressed as quantiles of probability distributions describing random variables in use, need not be specified to verify the safety condition. The proposed algorithm is based on fully probabilistic considerations, and those, according to Authors’ opinion, by their nature lead to more reliable, and at the same time, objective estimates.

It is presented in detail how the selection of a structural model describing the behaviour of a steel hall transverse frame when subject to fire exposure in a more or less complex way may affect the fire resistance evaluation for such a frame. In the examples compiled in this paper the same typical one-aisle and single-story steel hall is subjected to simulated fire action, each time following the same fire development scenario.Aresultant fire resistance is identified individually in each case, using various computational models, on an appropriate static equilibrium path obtained numerically. The resulting estimates vary, not only in the quantitative sense, but also in terms of their qualitative interpretation. It is shown that the greater the simplification of the model used, the more overstated the estimated fire resistance is in relation to its real value. Such an overestimation seems to be dangerous to the user, as it gives him an illusory but formally unjustified sense of the guaranteed safety level.