Cracking Cause of the Main Steam Line Hangers of a Stand-by Unit in Coastal Atmosphere

A backup thermal power plant in a coastal area of China resumed construction after a long-term shutdown. During the resumption inspection, it was found that two hangers of the main steam pipeline had broken. The cause of hanger fracture was analyzed through macro examination, chemical composition analysis, hardness testing, tensile testing, metallographic analysis, scanning electron microscopy, and energy spectrum analysis. The results show that there were two main reasons for the fracture of the hanger: firstly, the material was unqualified, and the Cr and Ni content were lower than the standard required values. Secondly, the coastal atmospheric environment contained a high amount of Cl, which led to intergranular corrosion and stress corrosion cracking of the stainless steel hangers. Corresponding measures were proposed for the causes of fracture failure.