Failure analysis of a bellows expansion joint in flue gas pipeline of catalytic cracking unit

•The main reason of failure is the improper heat treatment of bellows after welding forming.•The stiffness of the overall bearing structure of the expansion joint is too small to accelerate the failure of the bellows.•The influence of pipe bending moment is considered in finite element analysis.•The methods to prevent the failure of expansion joint is put forward pointedly.