An annular gasket for use between facing flanges of two flow conduit sections, the gasket including an annular gasket substrate made of polytetrafluoroethylene and having a first face opposite a second face. The first face includes a plurality of first serrations wherein the plurality of first serrations includes a plurality of first grooves and a plurality of first peaks, and the second face includes a plurality of second serrations wherein the plurality of second serrations includes a plurality of second grooves and a plurality of second peaks. The plurality of first peaks is aligned with the plurality of second peaks. The plurality of first peaks and the plurality of second peaks are compressible to a substantially flat surface when the conduit sections are joined together in a bolted configuration. An outer guide ring may be positioned exteriorly to the annular gasket substrate.