Valve Ball and Seat Tungsten carbide balls are used where extreme hardness and wear resistance is required; in such applications as bearings, ball screws, valves and flow meters. These balls are also used for coining and as pivots, detents and tips for gauges and tracers. Tungsten carbide itself is practically inert and extremely strong. Any attack is usually on the binder. Since other material is less expensive, the selection of tungsten carbide solely for corrosion resistance is usually not justified. In highly corrosive conditions, carbides with a more resistant binder can be supplied. Additional ball specification : ball roundness : 0.0001 inch (0.003 mm) maximum; ball surface roughness : 5RA maximum; tolerance shall to be ?.001 inch (?.025mm) for all ball diameter less than 2-inchs; tolerance shall to be ?.002 inch (?.050mm) for all ball diameter not less than 2-inchs(precision grade : excess or equal to 25).