These R-Type ring-joint gaskets in octagonal shape fit ASME16.50, API 6B, and ASME B16.5 flanges. roughness. The octagonal cross-section has a higher sealing efficiency than the oval and is a preferred gasket. R-Type ring-joint gaskets maintain their integrity for high-pressure applications. These gaskets are available in ring numbers R11 to R105, 150lb - 5000lb pressure class.