Abstract: Aiming at the cracking of the elbow weld junction at the inlet of the pipeline and the overstress on the inlet of flue gas turbine of heavy oil catalytic unit during the preheating process, theoretical calculation and practical monitoring of the thermal expansion displacement of the high-temperature heating pipeline at the flue gas turbine inlet are carried out to explore the quantitative monitoring method for the pipeline thermal displacement. By comparing the actual monitoring data with the theoretical value of calculated thermal displacement, it was analyzed that the jam fault in the horizontal pipe expansion at the inlet of flue gas turbine and the excessive thermal expansion of the vertical pipe were the main reasons for the cracking of the pipe weld and the overstressing at the inlet of flue gas turbine. According to the above reasons, scientific and reasonable piping replacement process and swing support improvement measures were developed so that the problem of the flue gas inlet piping was solved and the hidden danger in production was eliminated. The solution to this problem can provide reference for the operation monitoring and replacement of pipes and the improvement of swing support in similar devices.

Key words: flue gas turbine, piping, thermal expansion, displacement monitoring, swing support