Abstract: As a method to evaluate the capacity of flange connection system under external load, equivalent pressure method has the advantages of simple calculation and fast evaluation. It is widely used in petrochemical industry. However, the assessment of flange loadbearing capacity by this method cannot be quantified. Engineers can only compare the equivalent design pressure with the maximum allowable working pressure, resulting in conservative assessment results. This paper focuses on the study of the equivalent pressure method and discusses its conservatism combining with an engineering design case. It also introduces the external load correction coefficient to make it more reasonable to evaluate the reliability of flanges when adopting equivalent pressure method.

Key words: flange, equivalent pressure method, conservatism, external load correction coefficient