Research on Soil SCC Sensitive of Shan-jing Pipeline.pdf

Research on Soil SCC Sensitive of Shan-jing Pipeline Lianwei Wang1, Shaohua Dong2 and Guizhang Yu3 1 Doctor student, School of Materials Science and Engineering, University of Science Technology Beijing; No. 30 Xueyuan Road, Haidian District, Beijing 100083; Tel: 020 Fax: 020 Email: wei86711@ 2 Doctor, Department of Science Technology and Information, PetroChina Beijing Gas Pipeline Company, No.9 Datun Road, Chaoyang District, Beijing 100101; Tel:010 Email: Shdong@ 3 Director; Informationization Office, Guangdong Natural Gas Grid Co.,Ltd; No.1962, Jichang Road, Guangzhou 510503; Email: Yugz@ ABSTRACT Soil stress corrosion crack（SCC）is one of the major hazard factor that cause the failure of buried piping. This paper analyzed influence factors and pipeline failure mode of soil SCC; introduced the progress of soil SCC study; presented the test method and the criterion of soil SCC; and analyzed soil SCC sensitive of typical soil from Shan-jing pipeline 1#. It have very important reference value for similar research. KEYWORDS Pipeline; Soil; X60; SCC INTRODUCTION Stress corrosion cracking has been a vital threat to the safe operation of natural gas pipelines. It is now recognized that there are two forms of SCC penetration from the external surface of buried pipelines (National Energy Board, 1996). One is intergranular SCC and is usually called ‘‘high pH SCC’’. The other, near-neutral pH SCC, which is engendered by dilute ground water with a relatively low pH of around 6.5, has a transgranular, quasicleavage crack morphology with very little branching, and is designated “low pH SCC’’. Their characteristics are shown as table1 (Zhang et al., 2009). At the present time, HCO3-/CO32- solution is used commonly to simply simulate high pH environment, and NS4 is used commonly to simulate near-neutral pH environment. 149ICPTT 2011 ? 2011 ASCE Table 1. Characteristics of SCC of Pipel