The safety and reliability of pipelines will bring a huge challenge upon the construction of a large number of gas transmission pipelines in China. It has been known that two types of SCC (near-neutral SCC and high-pH SCC) commonly occur on the pipelines. Thus, there is an urgent need to investigate the potential SCC on the pipelines in China. In this paper, we report the SCC investigation on three gas transmission pipelines (one pipeline over 30 years old and two newly-constructed pipelines) in western and middle China. (i) For the old pipeline, we reviewed the failure cases and corrosion investigation collected in past years and excavated dozens of field sites to detect the anti-corrosion coating and cathode protection, and analyzed the reasons why SCC didn’t occur in the old pipeline yet. (ii) For these three pipelines, we evaluated the SCC sensitivity of line pipe steels in typical soil environment by using slow strain rate tests and other experiments. (iii) For pipelines in western China, we also analyzed the soil environment and operation pressure fluctuation. Based on the analysis, we summarized some conditions that are prone to SCC and present measurements of SCC prevention. Our investigation will build a solid foundation for the SCC prevention on all gas pipelines in the near future.

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