Analysis on pigging safety of a steep slope section of Myanmar-China Natural Gas Pipeline

During the pigging operation in an 80° slope section of Myanmar-China Natural Gas Pipeline, huge impact can be brought easily to the elbows at bottom of the pipeline, which could result in catastrophic consequences such as natural gas leakage. Herein, the process parameters such as the operating pressure and the operating speed of the pigs in the slope section, as well as the liquid holdup thereof, were obtained with OLGA software. On this basis, the stress and displacement model during pigging was established with the finite element software ANSYS and CAESAR II, the finite element analysis was also performed, and thereby recommendations on safe pigging were put forward. The results show that no excessive stress will be applied and the displacement is within a controllable range if a 4 000 kg pig is used under the current operating conditions. The water and soil conservation structure can fix and protect the pipelines effectively. In addition, when the weight of the pig is increased from 1 200 kg to 4 000 kg, the stress and displacement of the pipeline are increased by 12.3% and 1.3% respectively. Therefore, the research results are of great significance for improving the pigging efficiency and safety of the steep slope section, and could provide technical reference for the safe pigging of the steep slope sections.