ANSI AWWA C507-18 pdf free download – Ball Valves, 6 In. Through 60 In. (150 mm Through 1,500 mm)
General. The actuating forces required to operate a ball valve of a given size vary considerably and depend on the size of the valve, the differential operating pressure, the quantity of water flow, the configuration of waterway passages, and the seal design used. This standard covers the design of these valves and their actuators operating at a maximum differential pressure equal to or less than the design pressure and a maximum full-open port fluid velocity of 35 ft/s (10.7 m/s). Ball valves capable of operating under pressure–velocity conditions exceeding those found in this standard are available but are outside the scope of this standard. Fluid port velocities greater than 35 ft/s (10.7 m/s) have a higher probability of causing cavitation in piping systems, especially if valves are used to throttle flows. The 35-ft/s (10.7-m/s) port fluid velocity is not an upper limit to the flow that can be satisfactorily handled by ball valves. Piping systems capable of producing higher velocities should be studied by the system owner, system designer, or purchaser and manufacturer to ensure the most appropriate valve selection.
Considerations for Throttling Service. If a valve is to be installed for throttling service, the system owner, system designer, or purchaser must carefully evaluate the full range of differential pressures across the valve versus the downstream pressures in order to avoid damage by cavitation. Differential pressures across the valve versus downstream pressures for all angles of the ball, together with the hydraulic characteristics of the valve, must be determined and evaluated to ensure a successful installation. See AWWA Manual M49 for further explanation and information.
Valve and Piping Supports. To maintain the integrity of the valve, it is important to avoid subjecting the valve to pipe loads or external loads that drive the valve out of round, such as the use of valve foundations or supports without proper pipe supports. The valve should be supported independently of the adjacent piping, and the adjacent piping should be supported independently of the valve. Piping to and from the valve should be adequately supported and controlled. Valve inlet and outlet piping should be supported as near to the valve as practical. This arrangement removes most of the static load and allows identification of piping fit problems during installation and easier removal of the valve for maintenance. Design considerations should include allowable flange loadings, thermal expansion and contraction, and differential settlement.