1. Director, PipeChina West East Gas Pipeline Company, 1200 Century Ave., Pudong New Area, Shanghai 200120, China.
2. Engineer, China Petroleum Pipeline Engineering Company, No. 6 Jinyuan East Rd., Langfang Development Zone, Langfang 065000, China (corresponding author).
3. Engineer, PipeChina West East Gas Pipeline Company, 1200 Century Ave., Pudong New Area, Shanghai 200120, China.
4. Engineer, China Petroleum Pipeline Engineering Company, No. 6 Jinyuan East Rd., Langfang Development Zone, Langfang 065000, China.
5. Welding Technician, China Petroleum Pipeline Engineering Company, No. 6 Jinyuan East Rd., Langfang Development Zone, Langfang 065000, China.