This standard covers flanged cast-iron gate valves in sizes NPS 2 through 24 correspnoding th nominal pipe sozes in ANSI B36.10. This standard covers valves in pressure Claases 125 and 250 in ANSI B16.1 The valve is the outside screw-and-yoke (OSY) type with rising stem@ nonrising stem@ nonrising lahdwhell@ bolted bonnet and various types of gates. Classes 125 and 250 cast-iron valves made in accordance with this specification shall conform to Classes 150 and 300 steel valves made to the requirements of API Standard 600@ except as modified herein. The standard nomenclature for valve parts is shown in Figure 1@ which also illustrates an acceptable valve design.