Натурные испытания труб с локальными искажениями поверхностей

Abstract

Background The localized thermo-mechanical effects on the pipe often lead to a corresponding change in the geometric shape of their surfaces (formation of the dents of various forms). Aims and Objectives To show disadvantages of existing natural basic elements of the equipment with dents; to propose methods for obtaining the desired shape of the dent and to hold the test on the field samples. Methods In order to obtain dents without flat circular plots at the top the special curved cylindrical punches with the relevant guides were made. The vessels were tested for static pressure till the rupture at a special stand of Salavatneftemash OAO. Results Dent with the parameters mf = 5 (where ms = f0/S), and weakened by the sharp incision of the wall on 25 % had no impact on the carrying capacity of a cylindrical vessel. As a result of testing the initial deflection of the dent decreased for more than two times. At the same time the incision is much exposed, but it did not cause the failure. The vessel destroyed along the longitudinal joint, at the distance from the dents with the incision, at a pressure of Pc = 9 MPa, which is close to the value of the calculated collapsing pressure Pc of the vessel without dents. Estimated value of Pc was 8.8 MPa. Conclusion Further studies are needed to clarify and describe this phenomenon.