Abstract: Valve chamber is important for long-distance gas pipeline. But in operations, it has two defects: (1) nitrogen replacement of the trunk line cannot be completed directly in valve chamber; and (2) the gas cannot be supplied from the valve chamber directly to users. Considering the process, valve chamber is optimized by properly setting standard nitrogen injection port and reserved port, so that the nitrogen replacement of the trunk line can be completed directly in the valve chamber and the gas can be supplied from the reserved port directly to new users. New valve chamber process is analyzed by HAZOP. The results show that the process is incorporated into the pipeline SCADA system for real-time monitoring, and the gas leakage detection device can be used to more frequently inspect the operation, so as to facilitate the smooth application of the new process and maximize the operation safety. Scientific and reasonable addition of standard nitrogen injection port and reserved port for gas supply can help to optimize the operating process, improve the operating efficiency, reduce operational risks, decrease work quantities, save material cost, ensure pipeline integrity and keep downstream gas users not be affected.