Understanding Torque for Quarter-Turn Valves

Valve producers publish torques for his or her merchandise so that actuation and mounting hardware may be properly selected. However, published torque values often symbolize solely the seating or unseating torque for a valve at its rated pressure. While these are important values for reference, published valve torques don’t account for precise installation and operating characteristics. In order to discover out the precise working torque for valves, it’s needed to understand the parameters of the piping methods into which they are installed. Factors similar to installation orientation, direction of circulate and fluid velocity of the media all influence 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 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 edition. In addition to data on butterfly valves, the present edition also contains working torque calculations for other quarter-turn valves including plug valves and ball valves. Overall, this handbook identifies 10 elements of torque that may contribute to a quarter-turn valve’s working torque.
Example torque calculation summary graph
The first AWWA quarter-turn valve normal for 3-in. by way of 72-in. butterfly valves, C504, was revealed in 1958 with 25, 50 and a hundred twenty five psi strain courses. In 1966 the 50 and a hundred twenty five psi pressure courses have been increased to seventy five and one hundred fifty psi. The 250 psi stress class was added in 2000. The 78-in. and larger butterfly valve commonplace, C516, was first revealed in 2010 with 25, 50, 75 and one hundred fifty psi stress classes with the 250 psi class added in 2014. The high-performance butterfly valve normal was revealed in 2018 and includes 275 and 500 psi stress lessons in addition to pushing the fluid circulate velocities above class B (16 toes per second) to class C (24 ft per second) and class D (35 toes per second).
The first AWWA quarter-turn ball valve normal, C507, for 6-in. by way of 48-in. ball valves in a hundred and fifty, 250 and 300 psi strain lessons was revealed in 1973. In 2011, size range was elevated to 6-in. by way of 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 commonplace for resilient-seated cast-iron eccentric plug valves in 1991, the primary a AWWA quarter-turn valve standard, C517, was not published until 2005. The 2005 size vary was 3 in. via seventy two in. with a 175
Example butterfly valve differential stress (top) and move fee control windows (bottom)
stress class for 3-in. by way of 12-in. sizes and 150 psi for the 14-in. through 72-in. The later editions (2009 and 2016) haven’t elevated the valve sizes or pressure classes. 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 need 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 beneath improvement. This normal will encompass the same one hundred fifty, 250 and 300 psi stress classes and the same fluid velocity designation of “D” (maximum 35 ft per second) as the current C507 ball valve commonplace.
In general, all the valve sizes, move rates and pressures have increased for the reason that AWWA standard’s inception.
AWWA Manual M49 identifies 10 parts that affect operating torque for quarter-turn valves. These components fall into two general categories: (1) passive or friction-based elements, and (2) active or dynamically generated parts. Because valve manufacturers can’t know the actual piping system parameters when publishing torque values, published torques are usually restricted to the five components of passive or friction-based elements. These embrace:
Passive torque parts:
Seating friction torque
Packing friction torque
Hub seal friction torque
Bearing friction torque
Thrust bearing friction torque
The other five components are impacted by system parameters corresponding to valve orientation, media and circulate velocity. The elements that make up active torque include:
Active torque components:
Disc weight and heart of gravity torque
Disc buoyancy torque
Eccentricity torque
Fluid dynamic torque
Hydrostatic unbalance torque
When considering all these various active torque components, it’s potential for the precise working torque to exceed the valve manufacturer’s published torque values.
Although quarter-turn valves have been used in the waterworks trade for a century, they are being uncovered to higher service strain and flow price service conditions. Since the quarter-turn valve’s closure member is all the time positioned within the flowing fluid, these greater service situations instantly impression the valve. Operation of these valves require an actuator to rotate and/or maintain the closure member inside the valve’s body as it reacts to all the fluid pressures and fluid circulate dynamic conditions.
In addition to the increased service conditions, the valve sizes are also growing. The dynamic situations of the flowing fluid have greater impact on the bigger valve sizes. Therefore, the fluid dynamic results turn out to be extra important than static differential pressure and friction masses. Valves could be leak and hydrostatically shell examined throughout fabrication. However, the total fluid circulate conditions can’t be replicated earlier than website set up.
Because of the development for elevated valve sizes and increased working situations, it is more and more necessary 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, development and use.
The AWWA Manual of Standard Practice M forty nine is dedicated to the understanding of quarter-turn valves including working torque necessities, differential pressure, flow circumstances, throttling, cavitation and system set up differences that immediately influence the operation and profitable use of quarter-turn valves in waterworks methods.
The fourth version of M49 is being developed to include the modifications within the quarter-turn valve product standards and put in system interactions. A new chapter will be dedicated to strategies of management valve sizing for fluid flow, strain management and throttling in waterworks service. This methodology contains explanations on the usage of strain, circulate price and cavitation graphical home windows to offer the person a radical picture of valve efficiency over a range of anticipated system working conditions.
Read: New Technologies Solve Severe Cavitation Problems
About the Authors
Steve Dalton began his profession as a consulting engineer in the waterworks industry 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 worked at Val-Matic as Director of Engineering. He has participated in requirements creating organizations, including AWWA, MSS, ASSE and API. เกจ์วัดแรงดันน้ำมันเครื่อง holds BS and MS levels in Civil and Environmental Engineering together with Professional Engineering Registration.
pressure gauge น้ำ 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 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) within the improvement of their quarter-turn valve performance prediction methods for the nuclear energy business.

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