In the late nineteenth century, Olin J. Garlock devised a better way to seal piston rods in steam engines. Since then sealing materials have been developed for various industrial applications. Over the years, different manufacturing processes such as calendering and beater addition have improved the performance of fiber sheet gaskets for these applications; however, design concepts for their formulation remain similar regardless of manufacturing method.
OVERVIEW OF MATERIALS
Many of the applications for compressed fiber sheet gaskets involve elevated temperatures and/or high pressure, which require high bolt loading in flanged joint assemblies. Various materials are added to the fiber-binder matrix to sustain this high compressive loading. To provide strength, different types of fibers such as p-aramid (Kevlar™), cellulose, polyester, glass fiber, carbon fiber, and others are added. Some of these fibers are organic materials, which limits their use at elevated temperatures. Minerals in cylindrical form provide balance in the formulation due to their high-temperature stability and strength. To form a compact structure, materials of different sizes are used, including silica, carbon black, and other micro-sized fillers. Figure 1 illustrates the ingredients and microstructure of a compressed fiber sheet material.