Characterization of Orientation Effects of Spring Energized Seals Using 2D Simulations

Abstract

Abstract Spring energized seals, such as C-Rings, employ use of a high strength spring (Alloy-90, Alloy 718 etc.) within a soft jacket and hard liner (optional) to create high load, high performance seals. This seal design maintains its highperformance sealing capability due to the high contact pressure between the hardware and the seal jacket that is created due to the combination of the spring and optional liner. As such, spring-energized seals are widely used in critical applications such as nuclear energy and aerospace. As seal environments become more challenging, C-Rings must undergo higher temperatures, pressures, and stresses than before. This work evaluates two C-Ring orientations relative to the high pressure zone (open toward and away from the high pressure) and the effect on seal performance. For both orientations, this work examines several commonly used outer jacket sealing materials: aluminum, silver, and nickel. Spring material and liner material were kept constant for each simulation and remained within recommended design considerations for each outer jacket material. Each design was modeled using two-dimensional (2D) axis-symmetric simulations with the recommended gland/flange dimensions. 2D loading/pressurization steps were applied to each design and were as follows: loading to recommended compression displacement per seal design, then increase the inner diameter pressurization to 10,000 psi. Initial orientation of the C-Ring was away from the high pressure zone, then a similarly designed seal orientation was reversed with its opening toward the high-pressure side of the seal gland, and simulations were conducted as before to show system differences and reactionary responses of the seal. The results of this work indicate that, at high pressure, orientation is an important consideration when designing high performance metallic seals. When the internal area of the seal was subjected to high pressure with the spring oriented toward the high pressure, the liner and jacket were extruded away from the spring, resulting in a decrease in contact pressure; this increases the risk of leak path generation through the center of the seal element. Conversely, when the C-Ring is facing away from the high pressure zone and the outer area of the seal is subjected to high pressure, the spring contacts the outside of the flange and the physical constraint in the system creates additional axial force that increases contact pressure. This behavior is similar to an energizing effect. It was observed through physical trials in development that the force to compress the seal is significantly higher than any energizing effect gained due to system pressure. Secondarily, it was found that orienting the C-Ring away from the high pressure system media allows the seal design exhibit greater spring resilience while also avoiding corrosion and embrittlement effects on the spring from the system environment.