Experimental study on dynamics of rotatable bypass-valve in speed control pig in gas pipeline

Periodically pigging of oil and gas pipelines for dewatering, cleaning and inspecting becomes a standard industry procedure. Speed control unit is needed to control the speed of the pig and keep it work at a moderate constant speed, especially in the large diameter and high pressure gas pipelines. Rotatable bypass-valve is a necessary part in speed regulating unit, which is used to control the speed of pig by changing the amounts of the bypass flow across the pig body. However, the dynamics of the bypass-valve is complexity and indeterminacy during bypassing. As a result, in this paper, an experiment facility is set up to simulate the real working condition and get the dynamic characteristics of bypass-valve. The relationship among the torque, the opening of bypass-valve and the differential pressure over bypass-valve can be obtained in this experiment, which can provide the references to make control algorithm for speed control pig.