Corrosion Behaviour of Pipes in Soil and in Simulated Soil Solution

Paper No. 139
Mr Muhammad Wasim1, Prof Chun-Qing Li1, Dr Dilan  Robert1, Dr Mojtaba Mahmoodian1 – 1RMIT University, Melbourne, Australia

Abstract

Corrosion is a serious concern for asset managers and owners of the buried pipelines. Billions of dollars are spent every year on the repair and maintenance of the existing buried water pipes which were laid underground many decades ago. Recent investigations revealed that the external corrosion can be the root cause of failure for buried cast iron pipelines. Hence, various research works have been reported in literature to discover the corrosion influencing factors for pipes buried either in real soils or in simulated soil solutions. However, the corrosion models developed on the basis of pipes in these two environments are not largely comparable. In the current research, carefully controlled test program was executed to investigate  the  corrosion  behavior  between  the  pipes  buried  in  soil  and  simulated  soil solution. Firstly, a series of experiments was conducted using cast iron pipe sections buried in homogenous  real  corrosive  soil  environments  having  constant  void  ratio,  degree  of saturations and pHs. Secondly, cast iron pipe sections having similar material composition were submerged in simulated soil solution which was created from the corrosive components of the  same  soil. Results revealed a  substantial difference on the  metal  corrosion rates between the different interaction mediums. The research findings can be helpful to develop a correlation  model  to  compare  the  corrosion rates  of  cast  iron  metals  between  soil  and simulated soil solution mediums. Such models will support more reliable and convenient service  life  prediction of  cast  iron  pipes  when  the  corrosion experiments are  based  on simulated



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