The Application of Re-lowering in Technology of Pipeline Section in Zhongyuan Oilfield-Cangzhou Gas Transmission Pipeline

Zhongyuan Oilfield-Cangzhou Gas Transmission Pipeline is 361.891 km in total length with 426×7(8) in diameter, the average buried depth of the pipeline is 1.2 m. In recent years, the buried depth of the pipeline only rests about 1~1.5 m due to the artificial cause (soil, the brick-make material, is excavated off by the local peasants to brickyards), which result in the exposition of pipeline sections. To protect the pipeline, the re-lowering in technology of pipeline section is adopted, that is, re-excavation is made to a predetermined depth and then lowering in the pipe section in the case of allowable curvature radius of pipeline. In this paper, the authors present some technical requirements in lowering in procedure, backfill of pipe ditch and safety measures.