The primary driver for initial efforts in high temperature flange design came from improvements in the steam power generation industry that resulted in higher steam temperatures and pressures being used in the late 1920s and early 1930s. The initial work of Baumann [3] in 1930 looked at the creep of bolts and flange components of the joint and proposed a joint “life” relationship that accounted for the relative creep strength and relative flexibility of the bolt and flanges (Figure 1). The concept of joint life was related as a measure of time before flange leakage, rather than flange or bolt mechanical failure. The figure demonstrates the significant effect of the relative flexibilities on the joint life.
