Non-destructive testing of the strength of structural materials is currently based on the correlation between the results of laboratory tests of the strength of standard macro samples and the strength characteristics of the material in a real object. The heterogeneity of the strength properties of different zones of the material makes this correlation ambiguous, introducing uncertainty in the test results. The solution of the problem relates to the necessity of transition to the micro- and nano- control level that determines the strength, and to the applying of representative micro structural elements of the material and multipurpose physical nanoconstants as reference. The principles of selection of these elements and the method of assessing their strength characteristics are considered. The model proposed in the work has shown its effectiveness both in laboratory samples and in real industrial facilities.