Leakage Inspection of Cathodic Protection Current for Valve Chambers, Guizhou Oil & Gas Transmission Branch, Technology & Digital Center, PipeChina Southwest Pipeline Company

The Zhonggui Natural Gas Pipeline stretches approximately 356 kilometers within Guizhou Province. It adopts X80 grade steel pipes with a diameter of 1016 mm and a design pressure of 10 MPa. The pipeline starts in Xishui County, Zunyi City, and terminates at Guiyang Gas Transmission Station in Huaxi District, Guiyang City.

The route passes through 7 districts and 5 counties of 2 prefecture-level cities, as well as the Gui'an New Area. Along the line, there are 10 large tunnel crossings, 3 medium-to-large river crossings and 1 medium-to-large pipeline crossing/overpass. Three station yards are arranged along the pipeline, namely Zunyi Gas Transmission Station, Baiyun Gas Transmission Station and Guiyang Gas Transmission Station (co-constructed with the Guiyang Compressor Station of the China-Myanmar Pipeline). There are 20 line block valve chambers (No.54# to No.73#), including 12 monitoring valve chambers and 8 supervisory valve chambers. Four mainline cathodic protection stations are deployed, namely CP Station at Valve No.55#, Zunyi CP Station, CP Station at Valve Chamber No.66 and Baiyun CP Station.

Within the framework of the technical service contract, the project manager from the Technology & Digital Center of PipeChina Southwest Pipeline Company issued the inspection plan for cathodic protection current leakage of valve chambers under Guiyang Oil & Gas Transmission Branch on March 13, 2025. Upon receiving the assignment, our company rapidly mobilized personnel, equipment and materials to the site. We completed the cathodic protection current leakage inspection covering 31 valve chambers across 4 main pipelines from March 19 to March 31, 2025.