Research on Bypass-valve and its Resistance Characteristic of Speed Regulating PIG in Gas Pipeline

With the increasing demand of natural gas in China, large diameter pipelines traverse from the west to the east. Pigging of pipelines was a standard procedure. The high economic impact of the pipeline system did not allow decline the high flow speed of the gas, which is higher than 10m/s during the pigging or inspection. An innovative active speed control system in mechanical PIG with bypass-valve was required. This paper will outline the dynamic model and bypass flow control process in bypass PIG, also describe the structure features of several bypass-valves. Finally, theoretical and experimental analyze the resistance characteristic of the rotary transfer bypass-valve in speed variable PIG. Experimental result would be useful to the optimization of speed control unit and control algorithm.