Samara National Research University named after Academician S. P. Korolev, Samara, Russia

S. V. Voronin, Cand. Eng., Associate Prof., Dept. of Metal Technology and Aviation Materials Science, e-mail: voronin.sv@ssau.ru
K. K. Chaplygin, Postgraduate Student, Dept. of Metal Technology and Aviation Materials Science, e-mail: chapkostya96@mail.ru
V. S. Danilushkin, Postgraduate Student, Dept. of Metal Technology and Aviation Materials Science, e-mail: vladislavdan@bk.ru

The work presents a study of pipes made of steel after operation. Based on the existing regulatory documentation, according to geometric measurements of the diameter and thickness of the pipes, as well as the operating time of the superheater, the equivalent stresses in the pipe wall were calculated. Scale layers on the inner wall of the samples were determined. Using scanning probe microscopy, the elastic modulus of the base metal and scale layers was measured, the values of which were specified during modeling. Finite element models of the samples were constructed taking into account changes in the geometry of the pipe and the thickness of the resulting scale layer, as well as mechanical properties at operating temperatures. Stress distribution diagrams are presented for sample models with and without scale taken into account. Loads were applied simulating the effects of operating pressure. The influence of changes in pipe geometry and scale layer thickness on the stress-strain state is determined. A comparative analysis of the results of calculating stresses in the superheater pipe using the proposed method based on the finite element method using the MSC Nastran program with the results of equivalent stresses in the pipe wall obtained by calculation using existing regulatory documentation was carried out. It has been established that the values of equivalent stresses of the pipe wall after operation, obtained by the finite element modeling method taking into account the geometry without scale, are close to the calculated ones, and the values obtained taking into account the geometry with scale are much lower.

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