Stealth Valve
Conbraco
Crispin
Pratt
RUBBER SEATED BUTTERFLY VALVE SPECIFICATION
2.01 Standard Specification
The butterfly valves shall conform to the latest edition of AWWA-C504 Standard for Rubber Seated Butterfly Valves.
Valves
a) GENERAL : The valves shall be bubble-tight at rated pressures for bi-directional flow conditions, and shall be satisfactory for applications involving throttling service and valve operation after long periods of inactivity. The manufacturer shall have previously manufactured rubber-seated AWWA butterfly valves of the same design for a minimum period of five years. All valve manufacturers shall be in compliance with ANSI/NSF Standard 61 (Section 8) and state their approval file numbers for components in contact with potable water.
b) CLASS : The valves shall be designed for the velocities and pressure set out in these specifications and shall have Class B velocity designation.
c) VALVE BODY : The valve body shall be cast iron ASTM A-126 Class B, narrow body design. Body thickness shall be in strict accordance with AWWA C-504 latest revision where applicable. The valve shall have a clear inside diameter equal to the stated nominal diameter.
d) VALVE DISC : The valve disc shall be constructed of ductile iron ASTM A-536 with 316 stainless steel disc edge. The disc shall be free of hollow chambers. All surfaces shall be capable of visual inspection. Disc and shaft connections shall be made with stainless steel pins. Cast iron discs or alloy cast iron is not acceptable. Head loss analysis and Cv values shall be provided with the tender submission and will be taken into consideration by the Corporation during any tender analysis. Ship valves with valve discs 3-4 degrees open .
e) VALVE SEATS : All seats shall be of a natural or synthetic rubber. Rubber seats shall be recessed in the valve body. Valves under 500 mm shall have the seats recessed in the body and supported on three sides. Valve seats applied to the disc will not be accepted. Valves 600mm and larger shall have seats bi-directionally field adjustable around the full 360-degree circumference, under full pressure from the perimeter without removal of the valve. Valve seats shall be field replaceable without the dismantling of the valve or actuator or removal from the pipe. Valve seats shall be field replaceable without the requirements of pressure to the disc. Valve seats shall not project more than 6 mm (1/4 inch) beyond the valve inside diameter.
f) SHAFT SEALS : All shaft seals shall be of the self-adjusting chevron “V” type shaft seals.
g) STUFFING BOX : The stuffing box depth shall be sufficient to accept at least four rings of packing.
h) VALVE SHAFT : All valve shafts shall be one piece of two piece stub-shaft type 304 or 316 ground and polished stainless steel. The shaft diameter shall meet the latest requirements of AWWA C-504. Carbon steel shafts with stainless steel journals are not acceptable. The lower valve shaft shall incorporate a dual thrust bearing to permit valve positioning in a 360 degree circumference. The valve shaft shall be capable of horizontal mounting.
i) LIFTING LUGS: All valves shall incorporate four tapped holes strategically located on each flange outside diameter. Two eye bolts shall be supplied with each valve. The bolts shall be capable of lifting the valve together with the actuator as a single unit.
j) VALVE BEARINGS : All valves shall be fitted with sleeve type non-metallic, non-corrosive, self-lubricating bearings. Bearing loads shall not exceed 1/5 (one fifth) of the compressive strength of the bearing or shaft material.
2.01.2 Manual Actuators
Manual actuators selected by the supplier shall confirm to the latest edition of AWWA C504 Section 3.8 Valve Actuators as amended below:
a) The actuators shall be sized to operate with a maximum rim pull of 178N (40 lbs.) on handwheels and a maximum input torque of 109N-m (80 ft-lbs.) on 50 mm AWWA nuts. All chambered actuators shall incorporate non-metallic bearings isolating the rotating segment from the actuator housing
b) The actuators shall be designed to produce the torque which is necessary for seating and unseating of the valve based on bi-directional flow with a differential pressure equal to the specified working pressure applied to either face of the disc.
c) The actuators shall be designed to produce sufficient torque exceeding the maximum dynamic valve torque requirements based on bi-directional flow on differential pressures equal to the maximum specified working pressure and velocities. The Corporation shall give preference to those actuators meeting the specifications stated in Section 2.01.2(a).
d) The maximum number of turns to fully close or fully open the valve shall be as follows:
NOMINAL VALVE SIZE NO. OF TURNS
600 mm (24 inch) or less 50 or less
900 mm (36 inch) 150 or less
1050 mm (42 inch) 150 or less
The Corporation recognises that the rim pull and input torque requirements specified in Section 2.01.2(a) may govern the number of turns.
e) The actuators shall be equipped with tamper proof internal stop limiting devices to prevent over travel of the disc in the open and closed positions. All actuator components shall be capable of withstanding an input torque of 450 ft-lbs.
f) The actuators shall be provided with a diviner indicator that shall indicate directly the position of the disc from full open to fully closed, with markings at least at the quarter points of travel and number of turns to open or close. The diviner shall incorporate the direction to open or close the valve.
g) The actuators shall turn clockwise to close the valve.
Home | Contact Us | Site Map | Privacy Policy
Copyright Stealth Valve All Rights Reserved