Problems and practices in commissioning of the Lanzhou-Chengdu Crude Oil Pipeline

For the Lanzhou-Chengdu Crude Oil Pipeline, which frequently encounters rivers and spans high-relief areas, together with the fact that some facilities are not tested before commissioning, many problems may occur during commissioning, such as uncontrollable flowrates through pumps, super high pressures in outlet manifolds of pumps, air locks at high positions, sticking pigs, and unstable starting of pumping stations in lower sections during water-filling which may induce excessive high feeding pressures. Therefore, for purpose of smooth operation, some measures are taken. For example, correlation between electric current through pump and flowrates is used to achieve effective control over flowrates through pump, opening of outlet valve of feeding pump locally is reduced to minimize conflicts between pressures and flowrates, shutdown and re-start process is used to test the pump units under the conditions of lifting and squeezing of pigs and shutdown state of pipeline. Successful implementation of these measures and experiences may provide valuable references for commissioning of pipelines with significant drops.