Abstract

Lip-seal flange joints are commonly used in high-pressure heat exchanger design when there exists a significant temperature differential along the circumference of the heat exchanger flanges. This type of joint consists of two metal ring gaskets that are welded together to provide the necessary pressure seal. While conventional metal ring gaskets generally provide sufficient structural reliability, cracks have been reported to develop on the joints unexpectedly. This study investigates several special joint design features that aim to improve the reliability of such joints. Specifically, these features include machined pockets in the flange faces and weld overlay to house/constrain the lip-seal components, a self-alignment lip-seal feature, and tight fabrication tolerances. These improvement features mitigate thermal stresses on the lip-seal joints, thereby increasing the fatigue life of the joints. In addition, the self-alignment feature has the potential to aid in the optimization of field installation procedures. In the current work, the proposed improvement features are assessed using a series of FEA simulations to demonstrate their effectiveness. In particular, stress distributions at critical locations of the joint are compared between the new design and the conventional lip-seal design to quantify the relative improvement of the proposed design changes.

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