1.1 General This European Standard defines a Calculation method for bolted, gasketed, circular flange joints. Its purpose is to ensure structural integrity and control of leaktightness. The following equations use gasket parameters based on definitions and test methods specified in EN 13555. 1.2 Requirement for use of the Calculation method Where permitted, the Calculation method is an alternative to design validation by other means e.g. - special testing; - proven practice; - use of standard flanges within permitted conditions.