ПРОИСХОДИТ ЛИ СРЕЗ ВЕРШИН ВИТКОВ РЕЗЬБЫ НАСОСНО-КОМПРЕССОРНЫХ ТРУБ ОТ СТРАГИВАЮЩЕЙ НАГРУЗКИ?

Abstract

In scientific technical and academic literature different interpretation formula of Yakovlev - Shumilov concerning the consequences from the ultimate joint strength impact on the pumping compressor tubes’ column are met. There is an opinion that the excess of the stretching tensile force upon the pumping compressor tube of the ultimate joint strength dimension leads to the destruction of the thread part by means of thread loop apexes, because the contact site of the loops’ nipple and the coupling decreases at the expense of forming clearance between them. The second opinion contradicts such a development of events. The third opinion: at first the loop is cut in the main plane, because it bears the main strength, then the second that could not withstand the apex stress and so on. However, one must take into consideration that the thread loops are not isolated from each other apexes but they present a single continuous spiral chain. Birger I. A. also believes that “the phenomenon of the chain apex when the loops’ destruction occurs one after another, may happen only when the thread is fine, when the ratio of the diameter to the thread pitch is less than 15”. It has been shown by means of calculation that the ultimate joint strength has nothing in common with the thread loop apex. It is the cause of arising stress in the plane situated at an angle of 45 degrees to the planes on which axial and tangential stresses arise. This leads to the nipple body rapture of the pipe with the stress equal to the half of the pipe material yield point. The obviousness of the latter comes out from the third theory of strength. From these one may conclude that the ultimate joint strength does not lead to the thread profile apexes’ cutting but it causes its rapture on the tangential plane. There are pictures confirming this. The calculations of the thread part HTK on the strength from the ultimate joint strength impact have shown a substantial degree of safety on the cutting and on the external pressure impact with specifically sample absence of such by the stress in a tangential plane.