Performance of metal and polymeric O-ring seals during beyond-design-basis thermal conditions

Abstract

This paper summarizes the small scale thermal exposure test results of the performance of metallic and polymeric O-ring seals typically used in radioactive material transportation packages. Five different O-ring materials were evaluated: Inconel/silver, ethylene-propylene diene monomer (EPDM), polytetrafluoroethylene (PTFE), silicone, butyl, and Viton. The overall objective of this study is to provide test data and insights to the performance of these Oring seals when exposed to beyond-design-basis temperature conditions due to a severe fire. Tests were conducted using a small-scale stainless steel pressure vessel pressurized with helium to 2 bar or 5 bar at room temperature. The vessel was then heated in an electric furnace to temperatures up to 900 °C for a pre-determined period (typically 8 h to 9 h). The pressure drop technique was used to determine if leakage occurred during thermal exposure. Out of a total of 46 tests performed, leakage (loss of vessel pressure) was detected in 13 tests.

Characterization of Dielectric Relaxation Process by Impedance Spectroscopy for Polymers: Nitrile Butadiene Rubber and Ethylene Propylene Diene Monomer

“…Many kinds of rubbery polymers are used in O-rings for hydrogen gas sealing under high-pressure hydrogen infrastructure conditions; nitrile butadiene rubber (NBR), ethylene propylene diene monomer (EPDM), and fluoroelastomer (FKM) rubbers are used as sealants and gaskets in valves and pipelines [1][2][3][4][5][6]. Previous studies have investigated physical properties such as the glass transition, volume swelling, and thermal stability, mechanical properties such as tensile strength, compression, elongation, and shear behavior at high hydrostatic pressure, and transport properties such as permeability, diffusivity, and solubility of hydrogen.…”