Causes of 5-stage spheroidization of steam pipeline and its life evaluation

The 5-level spheroidization of P11 steel material in a steam pipeline was analyzed by metallographic examination, hardness test, high temperature tensile test and room temperature impact test. The spheroidization pipeline was comprehensively evaluated by pipeline life evaluation method to determine whether the pipeline could continue to use. The results show that the spheroidized pipeline had the characteristics of high spheroidization level of internal and external walls and low spheroidization level of central part. Heat treatment was the main reason for the 5-level spheroidization of pipeline materials. The pipeline could continue to be used, but inspection and maintenance need to be strengthened.