2.8.24 Water and Air Line Valves and Special

2.8.24               Water and Air Line Valves and Specialities

 

                        All valve shall be suitable for the service conditions i.e. Flow, temperature and pressure under which these are required to operate and those performing similar duties shall be interchangeable, with one another unless otherwise approved. All valves and connections shall be suitably protected to prevent damage and entry of dirt, till erected.

 

                        End to End dimensions shall be in accordance to ANSIB16.10 or as per codes to which they conform to.

 

                        All manually operated valves of all sizes 350 NB and above shall be provided with gear operator of proven quality, reputed make and conforming to internationally accepted standard.

 

                        All valves shall be fitted with open/close position indicators.

 

                        All valves shall be provided with hand wheels, extension spindles and floor stands or any other arrangement wherever required so that these can be operated manually with ease by a single operator from the nearest operat­ing floor either at a lower or higher elevation as the case may be. Wherever necessary for safety purpose, locking devices shall be furnished with valves.

 

                        All Gate and Globe valves shall be of outside screw and yoke (OS&Y) type and provided with back seat to permit repacking with valves in operation.

 

                        The actuator operated valves shall be designed on the basis of the following:

    

                        a)         The internal parts shall be suitable to support the stresses caused by the actuator.

    

                        b)         The valve actuator unit shall be suitably stiff so as not to cause vibrations, misalignment etc.

 

                        c)         Motorised Valves shall be provided with hand operating gear, hand wheel and clutching and declutching arrange­ment.

 

                        The size of all valves shall be the same as that of parent pipe.

 

                        The end connections shall comply with the following:

 

                        -           Socket welding (SW)                 -           ANSI B16.11

                        -           Butt welding (BW)                     -           ANSI B16.25.

                        -           Threaded (SC)                          -           ANSI B2.1

                        -           Flanged (FL)                             -           ANSI B16.5.

 

                        Gate valves shall be used for isolation purposes, Globe valves shall be used for regulation purpose, check valves shall be used for non-return service, and plug valves shall be used for isolation purpose in those lines where quick opening and closing is required in the system.

 

                        Double flanged or wafer type butterfly valves of low leakage rate conforming to AWWA-C-504, BS:5155 or any other approval equivalent latest standard edition can also be used for isolation, quick isolation and regula­tion purposes.

 

                        Material of construction shall be as follows:

 

For sizes below 50 mm and working pressure or shut off pressure (whichever is  higher) is upto 15 Kg/cm2(g)/ (upto 10 Kg/cm2(g) for Plug valves)
	Body/Wedge/Disc		Gun Metal
	Trim & Stem		Gun Metal
For sizes 50 mm and above and working pressure or shut off pressure (whichever is higher) upto 15 Kg/cm2(g).
	Body/Wedge/Disc		C.I. to IS 210 Gr. FG 220
	Trim & Stem		Brass/ Gun Metal
For all sizes and working pressure or shut off pressure (which ever is higher) is   above 15 Kg/cm2(g) (Above 10Kg/cm2 for plug valves).
	Body/Wedge/Disc		Cast/Forged carbon steel
	Wedge/Disc/Plug		Cast carbon steel with 13% Cr
	Trim and Stem		Stainless steel

 

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