ANSI AWWA C500-19 pdf free download – Metal-Seated Gate Valves for Water Supply Service
This standard describes iron-body, metal-to-metal seated, nonrising- stem (NRS) gate valves, including tapping gate valves, 3 in. (75 mm) through 72 in. (1,800 mm), and outside screw and yoke (OS&Y) rising-stem gate valves, 3 in. (75 mm) through 72 in. (1,650 mm), with either double-disc gates having parallel or inclined seats, or solid-wedge gates. These valves are suitable for use in approximately level settings within water systems. These valves are intended for applications where fluid velocities do not exceed 16 ft/sec (4.9 m/sec) when the valve is in the fully open position.
1.1.1 Valve pressure ratings. The minimum design working water pressure shall be 200 psig (1,379 kPa) for valves 12 in. (300 mm) and smaller, and 150 psig (1,034 kPa) for valves with diameters of 14 in. (350 mm) and larger.
1.1.2 Conditions and materials not described. This standard is not intended to describe special conditions of gate-valve installation or operation, such as built-in power drive, installation in unusually corrosive soil, conveyance of unusually corrosive water, excessive water hammer, or operation in a throttled position. Such conditions are beyond the intended scope of this standard and require special consideration in design and construction. Joint accessories for end connections, such as bolts, gaskets, glands, follower rings, and so forth, are not described in this standard.
concentrations of pollutants composed of low-molecular-weight petroleum products or organic solvents or their vapors. Documented research has shown that piping system materials (such as polyethylene and polyvinyl chloride) and elastomers used in gaskets and packing glands, are subject to permeation by lower-molecular-weight organic solvents or petroleum products. If a potable water, wastewater, or reclaimed water piping system must pass through such a contaminated area or an area subject to contamination, consult the manufacturer regarding permeation of pipe walls, valve components, jointing materials, and other piping system components before selecting materials for use in that area.
4.2.3 Dissimilar metals. In the presence of an electrolyte, direct contact between metals of dissimilar corrosion resistance may result in galvanic corrosion of the more active, less corrosion-resistant material. When dissimilar metals must be used for internal parts, the rate of corrosion shall be reduced as much as practical through the selection of materials that exhibit similar resistance to corrosion by placing a dielectric material between the metals or by applying a dielectric coating. When contact between dissimilar metals cannot be avoided, the assembly shall be designed so that the resulting corrosion will be minimized and will not adversely affect water quality or result in malfunctioning or premature failure of the assembly.
4.2.4 Mechanical and chemical properties. The requirements of ASME, ASTM, AWWA, or other standards to which references are made in this text shall govern the mechanical and chemical characteristics of the valve components. Whenever valve components are made in conformance with AWWA, ASME, ASTM, or other standards that include test requirements or testing procedures, the manufacturer or supplier shall comply with these requirements or procedures. The records of all tests shall, if required by the purchaser’s documents, be made available to the purchaser.