Understanding Torque for Quarter-Turn Valves

Valve manufacturers publish torques for their products in order that actuation and mounting hardware may be correctly selected. However, revealed torque values usually symbolize only the seating or unseating torque for a valve at its rated strain. While these are necessary values for reference, printed valve torques do not account for precise installation and working characteristics. In order to discover out the precise working torque for valves, it is necessary to know the parameters of the piping systems into which they are put in. Factors similar to installation orientation, path of flow and fluid velocity of the media all impression the actual operating torque of valves.
Trunnion mounted ball valve operated by a single performing spring return actuator. Photo credit score: Val-Matic
The American Water Works Association (AWWA) publishes detailed information on calculating working torques for quarter-turn valves. compound gauge ราคา appears in AWWA Manual M49 Quarter-Turn Valves: Head Loss, Torque, and Cavitation Analysis. Originally published in 2001 with torque calculations for butterfly valves, AWWA M49 is currently in its third version. In addition to information on butterfly valves, the current edition also includes working torque calculations for other quarter-turn valves including plug valves and ball valves. Overall, this guide identifies 10 components of torque that may contribute to a quarter-turn valve’s operating torque.
Example torque calculation abstract graph
The first AWWA quarter-turn valve commonplace for 3-in. via 72-in. butterfly valves, C504, was published in 1958 with 25, 50 and 125 psi strain courses. In 1966 the 50 and one hundred twenty five psi pressure lessons were increased to 75 and a hundred and fifty psi. The 250 psi strain class was added in 2000. The 78-in. and larger butterfly valve standard, C516, was first printed in 2010 with 25, 50, seventy five and a hundred and fifty psi strain classes with the 250 psi class added in 2014. The high-performance butterfly valve standard was printed in 2018 and includes 275 and 500 psi stress lessons in addition to pushing the fluid move velocities above class B (16 feet per second) to class C (24 ft per second) and class D (35 ft per second).
The first AWWA quarter-turn ball valve commonplace, C507, for 6-in. by way of 48-in. ball valves in 150, 250 and 300 psi strain lessons was published in 1973. In 2011, measurement vary was elevated to 6-in. via 60-in. These valves have all the time been designed for 35 ft per second (fps) most fluid velocity. The velocity designation of “D” was added in 2018.
Although the Manufacturers Standardization Society (MSS) first issued a product commonplace for resilient-seated cast-iron eccentric plug valves in 1991, the primary a AWWA quarter-turn valve normal, C517, was not revealed until 2005. The 2005 dimension range was 3 in. through 72 in. with a one hundred seventy five
Example butterfly valve differential pressure (top) and circulate rate management windows (bottom)
pressure class for 3-in. via 12-in. sizes and one hundred fifty psi for the 14-in. by way of 72-in. The later editions (2009 and 2016) have not elevated the valve sizes or stress courses. The addition of the A velocity designation (8 fps) was added within the 2017 edition. This valve is primarily used in wastewater service the place pressures and fluid velocities are maintained at decrease values.
The want for a rotary cone valve was recognized in 2018 and the AWWA Rotary Cone Valves, 6 Inch Through 60 Inch (150 mm by way of 1,500 mm), C522, is under improvement. This commonplace will encompass the same 150, 250 and 300 psi pressure courses and the identical fluid velocity designation of “D” (maximum 35 feet per second) as the current C507 ball valve normal.
In general, all the valve sizes, move charges and pressures have elevated since the AWWA standard’s inception.
AWWA Manual M49 identifies 10 components that have an result on operating torque for quarter-turn valves. These parts fall into two general classes: (1) passive or friction-based parts, and (2) active or dynamically generated elements. Because valve producers can’t know the actual piping system parameters when publishing torque values, revealed torques are typically restricted to the 5 elements of passive or friction-based parts. These embody:
Passive torque parts:
Seating friction torque
Packing friction torque
Hub seal friction torque
Bearing friction torque
Thrust bearing friction torque
The other five elements are impacted by system parameters similar to valve orientation, media and circulate velocity. The elements that make up energetic torque include:
Active torque components:
Disc weight and center of gravity torque
Disc buoyancy torque
Eccentricity torque
Fluid dynamic torque
Hydrostatic unbalance torque
When contemplating all these various energetic torque parts, it is attainable for the actual operating torque to exceed the valve manufacturer’s printed torque values.
Although quarter-turn valves have been used within the waterworks trade for a century, they’re being exposed to greater service strain and flow rate service situations. Since the quarter-turn valve’s closure member is always located within the flowing fluid, these higher service circumstances instantly impact the valve. Operation of those valves require an actuator to rotate and/or hold the closure member within the valve’s body as it reacts to all of the fluid pressures and fluid move dynamic circumstances.
In addition to the increased service situations, the valve sizes are also rising. The dynamic conditions of the flowing fluid have larger impact on the larger valve sizes. Therefore, the fluid dynamic results become more essential than static differential strain and friction masses. Valves could be leak and hydrostatically shell examined throughout fabrication. However, the total fluid flow circumstances can’t be replicated earlier than web site set up.
Because of the trend for increased valve sizes and elevated operating situations, it is more and more necessary for the system designer, operator and owner of quarter-turn valves to better understand the impact of system and fluid dynamics have on valve selection, development and use.
The AWWA Manual of Standard Practice M forty nine is devoted to the understanding of quarter-turn valves together with operating torque requirements, differential pressure, move conditions, throttling, cavitation and system set up differences that directly affect the operation and profitable use of quarter-turn valves in waterworks techniques.
The fourth edition of M49 is being developed to include the adjustments in the quarter-turn valve product requirements and installed system interactions. A new chapter might be devoted to methods of control valve sizing for fluid circulate, stress management and throttling in waterworks service. This methodology consists of explanations on using pressure, flow fee and cavitation graphical windows to supply the consumer a radical picture of valve efficiency over a variety of anticipated system working circumstances.
Read: New Technologies Solve Severe Cavitation Problems
About the Authors
Steve Dalton started his profession as a consulting engineer in the waterworks trade in Chicago. He joined Val-Matic in 2011 and was appointed president of Val-Matic in May 2021, following the retirement of John Ballun. Dalton beforehand worked at Val-Matic as Director of Engineering. He has participated in requirements growing organizations, together with AWWA, MSS, ASSE and API. Dalton holds BS and MS degrees in Civil and Environmental Engineering along with Professional Engineering Registration.
John Holstrom has been concerned in quarter-turn valve and actuator engineering and design for 50 years and has been an energetic member of both the American Society of Mechanical Engineers (ASME) and the American Water Works Association (AWWA) for more than 50 years. He is the chairperson of the AWWA sub-committee on the Manual of Standard Practice, M49, “Quarter-Turn Valves: Head Loss, Torque and Cavitation Analysis.” He has also worked with the Electric Power Research Institute (EPRI) in the improvement of their quarter-turn valve efficiency prediction methods for the nuclear power trade.

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