Abstract: Since the mandrel is regarded as the most critical thermal-deformation tool of the retained mandrel MPM pipe plant,its surface quality directly influences the dimensional tolerances and inner surface quality of the pipe as rolled.Moreover,the mandrel is also the most consumable operation tool in the rolling process of such MPM,thus its operational efficiency will determine the cost-effectiveness of the pipe production line.Based on analysis of the failure types and causes of the mandrel,actions for enhancing the mandrel service span are proposed.