Metallic Seal Ring Reusability

Abstract Metal-to-metal seals, exemplified by well-established designs like inverted T-shaped metallic seal rings, have emerged as preferred choices for both self-energized and pressure-energized sealing solutions. These seal designs find extensive application in clamp connections, compact flanges, or practically any metallic seal seat machined to provide the required diametrical interference and contact profile. By employing high-strength materials with elevated specified minimum yield strength, the reusability of these seals is substantially enhanced, consequently extending their operational lifespan from a sealability perspective. Unlike the classical ratcheting model of Bree, which is based on the combination of primary membrane stress and alternating secondary bending stress in the same direction, ratcheting in this context may occur solely due to secondary stresses during the make-up (assembly) and break-out (disassembly) phases. This study centers on simulating the makeup and break-out cycles of these seals. The primary objective revolves around evaluating how key design parameters — specifically seal sizing and yield strengths — impact the distribution of plastic strain and the overall potential for reusability of the seal rings. In pursuit of this goal, a comprehensive assessment utilizes an elastic-plastic stress analysis method, as detailed in section 5.5.7 of ASME VIII Div. 2. The study’s findings affirm that employing a minimum specified yield strength of 75 Ksi significantly enhances the reusability and operational lifespan of these seal types. This conclusion is in harmony with empirical insights gathered from various industries and is consistent with existing acceptance criteria, notably the stand-off value, which provides a quantitative measure of reusability potential.