Freezing bulge analysis and countermeasures for gas pipeline

Along with the throughput increase of West-to-East Gas Pipeline, the pressure of the pipeline increases continuously, which results in freezing bulge and deformation in several pipeline sections. The paper analyzes the freezing bulge reasons, one of which is that the gas temperature drops sharply due to volume increase after passing through the offtake pressure regulating device, another one is from the sensitive frost heaving coefficient of soil and underground water directly acted on the frost heaving. Some methods to deal with the freezing bulge are summarized combined with the actual running condition of the pipeline. These methods include heating method, soil replacement method, insulating method, intermittent gas transmission, electric tracing and warming, increasing the downstream gas supply pressure and setting up the winter emergency program of pipeline operation, etc.. Making use of the stage research result in freezing bulge prevention, field experiments in Zhengzhou and Bo'ai Compressor Station are performed, and satisfactory results are obtained. The research achievement can be taken as a reference for the as-built and proposed gas pipeline projects.