Understanding Torque for Quarter-Turn Valves

Valve manufacturers publish torques for his or her merchandise so that actuation and mounting hardware may be properly selected. However, printed torque values usually characterize solely the seating or unseating torque for a valve at its rated strain. While these are essential values for reference, published valve torques don’t account for actual set up and working characteristics. In order to determine the actual operating torque for valves, it’s essential to know the parameters of the piping techniques into which they are put in. Factors corresponding to installation orientation, course of circulate and fluid velocity of the media all impact the precise working 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 info on calculating operating torques for quarter-turn valves. This data 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 data on butterfly valves, the present version also consists of operating torque calculations for other 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 summary graph
AWWA QUARTER-TURN VALVE HISTORY
The first AWWA quarter-turn valve commonplace for 3-in. through 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 courses have been elevated to 75 and a hundred and fifty psi. The 250 psi stress class was added in 2000. The 78-in. and bigger butterfly valve standard, C516, was first revealed in 2010 with 25, 50, seventy five and 150 psi strain lessons with the 250 psi class added in 2014. The high-performance butterfly valve commonplace was revealed in 2018 and includes 275 and 500 psi strain courses as well as pushing the fluid move velocities above class B (16 ft per second) to class C (24 feet per second) and sophistication D (35 ft per second).
The first AWWA quarter-turn ball valve commonplace, C507, for 6-in. via 48-in. ball valves in 150, 250 and 300 psi strain courses was revealed in 1973. In 2011, measurement vary was elevated to 6-in. by way of 60-in. These valves have all the time 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 standard for resilient-seated cast-iron eccentric plug valves in 1991, the primary a AWWA quarter-turn valve commonplace, C517, was not printed till 2005. The 2005 size range was three in. via seventy two in. with a 175
Example butterfly valve differential pressure (top) and circulate price control windows (bottom)
stress class for 3-in. via 12-in. sizes and one hundred fifty psi for the 14-in. through 72-in. The later editions (2009 and 2016) haven’t elevated the valve sizes or strain courses. The addition of the A velocity designation (8 fps) was added within the 2017 version. This valve is primarily utilized in wastewater service the place pressures and fluid velocities are maintained at decrease values.
The want for a rotary cone valve was acknowledged in 2018 and the AWWA Rotary Cone Valves, 6 Inch Through 60 Inch (150 mm via 1,500 mm), C522, is beneath growth. This commonplace will encompass the same one hundred fifty, 250 and 300 psi stress courses and the identical fluid velocity designation of “D” (maximum 35 ft per second) as the current C507 ball valve commonplace.
In common, all of the valve sizes, flow charges and pressures have increased for the reason that AWWA standard’s inception.
COMPONENTS OF OPERATING TORQUE
AWWA Manual M49 identifies 10 parts that have an effect on working torque for quarter-turn valves. These parts fall into two common categories: (1) passive or friction-based parts, and (2) lively or dynamically generated components. Because valve producers cannot know the precise piping system parameters when publishing torque values, printed torques are typically limited to the 5 components of passive or friction-based components. 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 corresponding to valve orientation, media and flow velocity. The components that make up energetic torque include:
Active torque components:
Disc weight and heart of gravity torque
Disc buoyancy torque
Eccentricity torque
Fluid dynamic torque
Hydrostatic unbalance torque
When contemplating all these numerous energetic torque components, it is possible for the precise working torque to exceed the valve manufacturer’s revealed torque values.
WHY IS M49 MORE IMPORTANT TODAY?
Although quarter-turn valves have been used within the waterworks industry for a century, they are being exposed to greater service pressure and circulate fee service situations. Since the quarter-turn valve’s closure member is all the time situated in the flowing fluid, these higher service circumstances immediately impact the valve. Operation of those valves require an actuator to rotate and/or hold the closure member throughout the valve’s physique because it reacts to all of the fluid pressures and fluid move dynamic situations.
In addition to the increased service situations, the valve sizes are also rising. The dynamic conditions of the flowing fluid have greater effect on the larger valve sizes. Therefore, the fluid dynamic effects turn out to be more essential than static differential stress and friction masses. Valves could be leak and hydrostatically shell examined throughout fabrication. However, the total fluid move situations can’t be replicated before site set up.
Because of เกจวัดแรงดัน4บาร์ for elevated valve sizes and elevated working situations, it’s increasingly essential for the system designer, operator and owner of quarter-turn valves to higher understand the impression of system and fluid dynamics have on valve selection, building and use.
The AWWA Manual of Standard Practice M 49 is devoted to the understanding of quarter-turn valves including working torque requirements, differential strain, flow situations, throttling, cavitation and system set up differences that immediately influence the operation and successful use of quarter-turn valves in waterworks techniques.
AWWA MANUAL OF STANDARD PRACTICE M49 4TH EDITION DEVELOPMENTS
The fourth edition of M49 is being developed to incorporate the adjustments within the quarter-turn valve product standards and put in system interactions. A new chapter might be devoted to methods of management valve sizing for fluid move, pressure control and throttling in waterworks service. This methodology consists of explanations on the use of stress, flow fee and cavitation graphical home windows to supply the user a radical picture of valve performance over a range of anticipated system operating situations.
Read: New Technologies Solve Severe Cavitation Problems
About the Authors
Steve Dalton started his profession as a consulting engineer within the waterworks business 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 previously labored at Val-Matic as Director of Engineering. He has participated in standards developing organizations, together with AWWA, MSS, ASSE and API. Dalton holds BS and MS degrees in Civil and Environmental Engineering together 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 energetic 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 additionally labored with the Electric Power Research Institute (EPRI) within the growth of their quarter-turn valve efficiency prediction methods for the nuclear energy industry.
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