Abstract: Many types of single-tube pass floating head heat exchanger have been applied in petrochemical units for many years.According to the connecting structure between the tube channel outlet pipe at the floating head and rear shell cover,this article sums up the three structure types in engineering.For the commonly used type of the annular clamping plate and the flange with external gasket connecting structure,the article gives the detailed mechanical analysis based on the interaction between the annular clamping plate and the flange with external gasket and design formulas so as to realize the more accurate engineering design and calculation.