Abstract: Flue gas temperature is very high at the inlet of convection sections. High chromenickel alloy cast tube sheets are often used for supporting of convection coils. In recent years, leakage of convection coils often occur because of failure and cracking of cast tube sheets in use. This paper described the damage and replacement of the cast tube sheet of a foreign heater. Meanwhile, the stress analysis software ANSYS was applied to analyze and simulate the stress of the cast tube sheet under various working conditions, and the causes of cracking were found. According to the above reasons, the material of the original tube sheet was reselected and the structure of the tube sheet was redesigned to ensure the long-term safe and stable operation of the heater.

Key words: heater, high chrome-nickel alloy, cast tube sheet, failure cracking, material selection, stress analysis