The effect of temperature on flanged joint operation has been identified as a major problem since the early 1940's. The present flange design standards require the designer to analyze the effects of temperature without providing guidance on exactly how to do so. The ASME code simply instructs the designer to take temperature into consideration. The CEN Code includes a simplified axial expansion calculation but provides no method for determining the component temperatures and does not include the effects of differential radial expansion. This bulletin outlines a complete method for the calculation of the joint component temperatures and stresses during both steady state and transient operation. The method enables the designer to determine the effect of temperature on the flange and therefore comply with the requirements of both the ASME and CEN design methods. It also enables the end-user to determine whether the effects of temperature are significant in the leakage of problematic pressure vessel and piping flanged joints.