Valve producers publish torques for their products in order that actuation and mounting hardware can be properly selected. However, published torque values often symbolize only the seating or unseating torque for a valve at its rated stress. While these are essential values for reference, printed valve torques do not account for actual set up and operating traits. In order to determine the precise operating torque for valves, it is necessary to know the parameters of the piping systems into which they’re installed. Factors corresponding to set up orientation, course of circulate and fluid velocity of the media all influence the precise operating torque of valves.
Trunnion mounted ball valve operated by a single appearing spring return actuator. Photo credit: Val-Matic
The American Water Works Association (AWWA) publishes detailed info on calculating working torques for quarter-turn valves. This data seems in AWWA Manual M49 Quarter-Turn Valves: Head Loss, Torque, and Cavitation Analysis. Originally revealed 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 version also consists of operating torque calculations for different quarter-turn valves together with plug valves and ball valves. Overall, this guide identifies 10 parts of torque that can contribute to a quarter-turn valve’s working 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 a hundred twenty five psi pressure courses. In 1966 the 50 and a hundred twenty five psi stress classes have been increased to 75 and one hundred fifty psi. The 250 psi strain class was added in 2000. The 78-in. and larger butterfly valve commonplace, C516, was first revealed in 2010 with 25, 50, 75 and 150 psi strain courses with the 250 psi class added in 2014. The high-performance butterfly valve normal was published in 2018 and includes 275 and 500 psi stress lessons as properly as pushing the fluid circulate velocities above class B (16 feet per second) to class C (24 feet per second) and sophistication D (35 feet per second).
The first AWWA quarter-turn ball valve commonplace, C507, for 6-in. by way of 48-in. ball valves in a hundred and fifty, 250 and 300 psi strain lessons was printed in 1973. In 2011, size vary was increased 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 standard for resilient-seated cast-iron eccentric plug valves in 1991, the first a AWWA quarter-turn valve normal, C517, was not revealed until 2005. The 2005 size vary was three in. via seventy two in. with a 175
Example butterfly valve differential strain (top) and circulate fee management windows (bottom)
strain class for 3-in. by way of 12-in. sizes and a hundred and fifty psi for the 14-in. via 72-in. The later editions (2009 and 2016) haven’t elevated the valve sizes or stress lessons. The addition of the A velocity designation (8 fps) was added in the 2017 edition. 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 beneath improvement. This commonplace will encompass the same 150, 250 and 300 psi strain classes and the same fluid velocity designation of “D” (maximum 35 ft per second) as the present C507 ball valve normal.
In general, all the valve sizes, circulate charges and pressures have increased since the AWWA standard’s inception.
COMPONENTS OF OPERATING TORQUE
AWWA Manual M49 identifies 10 elements that affect working torque for quarter-turn valves. These components fall into two common classes: (1) passive or friction-based parts, and (2) active or dynamically generated components. Because valve producers can not know the precise piping system parameters when publishing torque values, revealed torques are typically limited to the 5 elements of passive or friction-based parts. These include:
Passive torque components:
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 such as valve orientation, media and flow velocity. The elements that make up lively torque include:
Active torque components:
Disc weight and middle of gravity torque
Disc buoyancy torque
Eccentricity torque
Fluid dynamic torque
Hydrostatic unbalance torque
When contemplating all these various lively torque elements, it is potential for the actual operating torque to exceed the valve manufacturer’s printed torque values.
WHY IS M49 MORE IMPORTANT TODAY?
Although quarter-turn valves have been used within the waterworks industry for a century, they’re being exposed to greater service pressure and flow rate service situations. Since the quarter-turn valve’s closure member is all the time located in the flowing fluid, these larger service situations directly influence the valve. Operation of these valves require an actuator to rotate and/or hold the closure member inside the valve’s physique because it reacts to all the fluid pressures and fluid circulate dynamic situations.
In addition to the increased service circumstances, the valve sizes are also increasing. The dynamic circumstances of the flowing fluid have greater effect on the larger valve sizes. Therefore, เกจ์ออกซิเจนsumo turn out to be more necessary than static differential strain and friction loads. Valves can be leak and hydrostatically shell tested throughout fabrication. However, the complete fluid flow conditions cannot be replicated before site set up.
Because of the trend for elevated valve sizes and elevated operating circumstances, it’s more and more 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 selection, building and use.
The AWWA Manual of Standard Practice M forty nine is dedicated to the understanding of quarter-turn valves including working torque requirements, differential strain, flow conditions, throttling, cavitation and system installation differences that instantly influence the operation and successful use of quarter-turn valves in waterworks methods.
AWWA MANUAL OF STANDARD PRACTICE M49 4TH EDITION DEVELOPMENTS
The fourth version of M49 is being developed to include the modifications within the quarter-turn valve product requirements and put in system interactions. A new chapter shall be devoted to strategies of control valve sizing for fluid circulate, pressure control and throttling in waterworks service. This methodology contains explanations on using strain, circulate price and cavitation graphical windows to provide the person an intensive image of valve efficiency over a variety of anticipated system working circumstances.
Read: New Technologies Solve Severe Cavitation Problems
About the Authors
Steve Dalton began his career as a consulting engineer within 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 standards creating organizations, including 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 concerned 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 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 additionally labored with the Electric Power Research Institute (EPRI) in the improvement of their quarter-turn valve efficiency prediction strategies for the nuclear power industry.
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