Influencing factors and determination methods of gas pipeline pigging cycle

Influencing factors of gas pipeline pigging cycle are analyzed to determine the minimum allowable transportation efficiency, maximum allowable volume of accumulated fluid and maximum allowable pressure drop as the pigging reference standard. On the basis of hydraulic friction factor, pipeline flow and transmission efficiency, a theoretical judgment process is proposed to determine whether pigging operations are needed in the case of branch pipe connection or no branch pipe connection. Software simulation method of determining pigging cycle by simulating static accumulated fluid volume and combining liquid carrying capacity is introduced. Taking Sulige North Second Trunk as an example, specific application steps of the two methods are elaborated and limitation of the theoretical judging process is analyzed. The results show that a reasonable pigging reference standard shall be selected and an appropriate calculation method used for different application situations to determine the pigging cycle. The reasonable volume of accumulated fluid and two-phase pressure drop prediction related expressions shall be selected for different pipeline media and pipeline transmission conditions to determine a reasonable pigging program.