Testing and analysis of pipeline ball valves: Part 1

摘要

In part 1 of this two part article, the author focuses on the importance of pipeline ball valve external loading bending tests and the determination of bending load applying way and size. He also discusses the construction of the external loading bending test device and the content and method of the test. Through the external load bending test and analysis, it can be seen that when the displacement direction of the pipeline ball valve is the same as that of the bending load, the displacement at the bottom can be the maximum value at the maximum bending load with no effect on the sealing performance of the pipeline ball valve and the test pipe with the coactions of media pressure and external bending load. With regard to the strength safety of the pipeline ball valve body main welding and transition section material, the circumferential weld of the transition section material on the pipeline ball valve body and the test pipe is the weakest joint, and the tensile stress at the bottom near the circumferential welding in the test pipe approaches the yield strength of the test pipe. The torque of the pipeline ball valve increases but remains less than the design torque. Meanwhile if the safety coefficient of the selected actuator is more than 1.5, there is a higher safety allowance, the movement of the valve in the torque test is flexible and the performance stable.