Understanding Torque for Quarter-Turn Valves

Valve producers publish torques for his or her products so that actuation and mounting hardware can be properly chosen. However, revealed torque values often characterize solely the seating or unseating torque for a valve at its rated pressure. While these are essential values for reference, printed valve torques don’t account for actual installation and working traits. In order to determine the actual working torque for valves, it’s needed to know the parameters of the piping techniques into which they’re installed. Factors similar to set up orientation, path of move and fluid velocity of the media all impact the precise working torque of valves.
Trunnion mounted ball valve operated by a single appearing spring return actuator. Photo credit score: Val-Matic
The American Water Works Association (AWWA) publishes detailed data on calculating operating torques for quarter-turn valves. This info seems in AWWA Manual M49 Quarter-Turn Valves: Head Loss, Torque, and Cavitation Analysis. Originally printed in 2001 with torque calculations for butterfly valves, AWWA M49 is at present in its third version. In addition to information on butterfly valves, the current version also consists of operating torque calculations for different quarter-turn valves including plug valves and ball valves. Overall, this guide identifies 10 components of torque that can contribute to a quarter-turn valve’s operating torque.
Example torque calculation abstract graph
The first AWWA quarter-turn valve normal for 3-in. by way of 72-in. butterfly valves, C504, was printed in 1958 with 25, 50 and 125 psi stress lessons. In 1966 the 50 and one hundred twenty five psi stress classes were elevated to seventy five and one hundred fifty psi. The 250 psi stress class was added in 2000. The 78-in. and larger butterfly valve normal, C516, was first published in 2010 with 25, 50, seventy five and one hundred fifty psi pressure classes with the 250 psi class added in 2014. The high-performance butterfly valve normal was printed in 2018 and consists of 275 and 500 psi pressure classes as well as pushing the fluid flow velocities above class B (16 feet per second) to class C (24 ft per second) and class D (35 feet per second).
The first AWWA quarter-turn ball valve standard, C507, for 6-in. via 48-in. ball valves in one hundred fifty, 250 and 300 psi strain classes was published in 1973. In 2011, size range was elevated to 6-in. through 60-in. These valves have at all times been designed for 35 ft per second (fps) maximum fluid velocity. The velocity designation of “D” was added in 2018.
Although the Manufacturers Standardization Society (MSS) first issued a product normal for resilient-seated cast-iron eccentric plug valves in 1991, the first a AWWA quarter-turn valve commonplace, C517, was not published till 2005. The 2005 measurement range was 3 in. via seventy two in. with a a hundred seventy five
Example butterfly valve differential pressure (top) and circulate rate management windows (bottom)
pressure class for 3-in. through 12-in. sizes and one hundred fifty psi for the 14-in. via 72-in. The later editions (2009 and 2016) have not elevated the valve sizes or strain courses. The addition of the A velocity designation (8 fps) was added in the 2017 version. This valve is primarily used in wastewater service where pressures and fluid velocities are maintained at lower 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 through 1,500 mm), C522, is under improvement. This normal will embody the same 150, 250 and 300 psi pressure classes and the identical fluid velocity designation of “D” (maximum 35 toes per second) as the current C507 ball valve standard.
In common, all the valve sizes, move charges and pressures have increased because the AWWA standard’s inception.
AWWA Manual M49 identifies 10 components that have an effect on operating torque for quarter-turn valves. These elements fall into two basic classes: (1) passive or friction-based components, and (2) energetic or dynamically generated components. Because valve producers can’t know the precise piping system parameters when publishing torque values, printed torques are usually limited to the 5 parts of passive or friction-based elements. These embody:
Passive torque parts:
Seating friction torque
Packing friction torque
Hub seal friction torque
Bearing friction torque
Thrust bearing friction torque
The different five parts are impacted by system parameters corresponding to valve orientation, media and move velocity. The parts that make up active torque embrace:
Active torque parts:
Disc weight and heart of gravity torque
Disc buoyancy torque
Eccentricity torque
Fluid dynamic torque
Hydrostatic unbalance torque
When contemplating all these various active torque elements, it is potential for the actual operating torque to exceed the valve manufacturer’s revealed torque values.
เกจวัดแรงดันปั๊มลม IS M49 MORE IMPORTANT TODAY?
Although quarter-turn valves have been used within the waterworks business for a century, they are being exposed to greater service strain and move price service conditions. Since the quarter-turn valve’s closure member is always positioned within the flowing fluid, these higher service conditions instantly impact the valve. Operation of those valves require an actuator to rotate and/or maintain the closure member within the valve’s body because it reacts to all of the fluid pressures and fluid move dynamic circumstances.
In addition to the increased service circumstances, the valve sizes are also rising. The dynamic circumstances of the flowing fluid have higher impact on the bigger valve sizes. Therefore, the fluid dynamic results turn out to be more essential than static differential stress and friction masses. Valves could be leak and hydrostatically shell tested during fabrication. However, the total fluid flow circumstances can’t be replicated before website set up.
Because of the development for elevated valve sizes and elevated operating circumstances, it’s increasingly essential for the system designer, operator and owner of quarter-turn valves to better perceive the impression of system and fluid dynamics have on valve choice, construction and use.
The AWWA Manual of Standard Practice M forty nine is devoted to the understanding of quarter-turn valves including operating torque necessities, differential strain, move conditions, throttling, cavitation and system installation variations that directly influence the operation and profitable use of quarter-turn valves in waterworks techniques.
The fourth edition of M49 is being developed to include the changes in the quarter-turn valve product standards and put in system interactions. A new chapter will be dedicated to methods of control valve sizing for fluid flow, pressure management and throttling in waterworks service. This methodology consists of explanations on using stress, circulate price and cavitation graphical home windows to supply the consumer a thorough image of valve efficiency over a spread of anticipated system operating circumstances.
Read: New Technologies Solve Severe Cavitation Problems
About the Authors
Steve Dalton began 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 labored at Val-Matic as Director of Engineering. He has participated in standards creating 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 involved in quarter-turn valve and actuator engineering and design for 50 years and has been an lively member of both the American Society of Mechanical Engineers (ASME) and the American Water Works Association (AWWA) for greater 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 growth of their quarter-turn valve efficiency prediction methods for the nuclear energy trade.

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