Evaluation of Performance Characteristics of a Surface Texturized Metallic Seal Using Helium Mass Spectrometry and Numerical Simulation

Abstract Static sealing solutions require loading in compression to achieve low leak rates. HELICOFLEX® seals are a spring-energized design that have a increased reaction force on contact and lower leak rates than traditional O-ring or C-ring designs. HELICOFLEX® TEXEAL® is an iteration with patterned features in the seal jacket designed to achieve a lower load response with minimal loss in sealing performance. Sealing performance is evaluated using helium mass spectrometry leak detection according to the American Society for Nondestructive Testing, Inc. (ASNT) protocols. The benefit of this method is high sensitivity on a detection range of 10−5 Pa-m3/s to 10−13 Pa-m3/s for this test setup. To evaluate the performance of the textured finish, three prototype seal designs were tested with a focus on load and leak rate characteristics. Each seal design had a similar surface finish with differently designed load-response. The goal of the present work was to assess the initial textured surface concept in order to inform more robust and targeted future iterations. In particular, this texturized seal could offer a viable metallic alternative to traditional high-load elastomeric seals made of perfluoroelastomeric compounds such as FFKM and other PFAS-based options. This could provide effective sealing at higher temperatures in applications with similar load and leak requirements of elastomeric material seals. Three seal configurations with different geometric and material dimensions. Seals 1 and 2 demonstrated more inconsistent performance than the larger Seal 3 cross-section; this is likely due to manufacturing variance that would be improved in further iterations or seal ovalization that can be minimized with simulation guided design. Seal 3 exhibited a high degree of repeatability with leak rates in the 10−6 Pa-m3/s range. This suggests that the texturized pattern design, manufacturing tolerances and material/geometric properties of Seal 3 may be more suitable for achieving the intended sealing performance of the texturized seal design. To guide future iterations, the work was compared with a three-stage performance numerical simulation. The first phase modeled mechanical performance at a seal cross-section which investigated load compression curves and ovalization using Finite Element Analysis (FEA). The second phase evaluated/modeled the surface interactions at variable contact pressures using hardening models and surface field analysis. The third phase evaluated a leak rate model for texturized and nontexturized seal designs using mass flow modeling. Physical test data was compared to simulation predictions in the first and third phases and guided selection of factors to optimize for future design iterations. Future work will focus on further analyzing and testing the effects of pattern geometry, surface deformation, material selection, and compression forces on leak rate performance.