The making of thread of plastic details is comparatively difficult (as compared to metals). This is due to the physical and mechanical processes that occur in the proсess of manufacture of specific threaded parts from plastics by pressing and injection molding. This is due to the physical and mechanical processes that occur during the manufacture of specific threaded parts made of plastics by method pressing and injection molding. Also, the mechanics of the formation of plastic threads on parts of oilfield equipment differ in their specific properties from threads obtained by mechanical machining on metals. Since threaded surfaces on plastic parts are formed in press-molds depending on materials and conditions: temperature, pressure and manufacturing time. These regime parameters and controlled parameters play a certain role in ensuring the physical and mechanical properties of parts during the manufacturing process. In this regard, this article discusses the calculation of the executive sizes of threaded signs and rings for the manufacture of plastic parts of oilfield equipment. It has been established that when the load is distributed over the turns, the height of the ring affects only the value of the hyperbolic cone. Moreover, the higher the ring, the less the upper turn of thread will be loaded. The useful height of the ring is selected depending on average diameter of thread.