Welded Bonnet Piston & Ball Check Valves — Basic Configuration, ASME Integral Flanged Ends

About this product

PRODUCT FEATURES: • Outside Screw and Yoke (OS&Y). • Self aligning two piece packing gland. • Integral backseat. • Integral body flanges. • Bonnet Extension. DESIGN TYPE W3 FULL PENETRATION WELD BODY-BONNET CONNECTION

From the catalogue's introduction to this valve type: PISTON & BALL CHECK VALVES Full die forged structure for all pressure containing parts. Standard construction of body-bonnet connections is bolted bonnet type. Welded bonnet is avaliable as alternative construction. Flanged valves are provided with flanges integral with the body forgings. Standard gasket design for bolted-bonnet valves is spiral wound type up to class ASME 1500. Ring Joint gaskets are standard for ASME 2500 and above. SPW/RJ are available on request for all pressure classes as option. Sealing surfaces are machined to the tightest tolerances and lowest roughness to ensure trouble free shut off. Body-guided disc for perfect seat and disc alignment. Disc is machined to the tightest tolerances to ensure trouble free shutoff and cycling. Precision guided closure member for perfect seating surfaces alignment. Closure member can be spring loaded for positive closure in any position. PISTON & BALL CHECK VALVE DESCRIPTION Piston and ball check valves, like all check valves, are used to prevent back flow in the line. Standard valve design has no spring in order to minimize cracking pressure and pressure drop, it will only function properly when installed in a horizontal line. As an option the designs can include a spring to assist closing and for use in 90-degree styles installed in vertical lines. PISTON CHECK VALVE The pressure of the fluid passing through a system opens the valve, while any reversal of flow will close the valve. In Piston, or lift, check valves a body-guided disc moves within the body bore. The body guide ensures alignment of the seat and disc when the valve closes. The valve is installed with the flow under the disc, so that the inlet line pressure and flow rate will force the disc to "lift" off the seat and allow the line fluid to flow through the valve. Should the flow suddenly reverse itself, the disc will automatically and quickly, assisted by the weight of the disc, be forced to the closed position, preventing the line fluid from returning. Exercise caution when these valves are used for dirty media because that media could cause the disc to stick inside the body bore. BALL CHECK VALVE The function of ball check valves is similar to the piston check, but the ball check valves use a "ball" inside the body to control the movement of flow. The ball is free to rotate, resulting in even wear and a wiping action between the ball and seat. This feature makes ball checks useful for viscous media. High flow capacity port sizes and disc retraction to minimize flow velocities and maximize valve service life. Low cracking pressure design. Fast response time to prevent backflow and adequate valve seating to prevent seat slamming. Standard seat design is screwed-in type, integral type is avaliable as alternative construction or in case of bolted bonnet design. Extra thickness of the seat ring provides sufficient material to renew the seating surface over and over again.