Understanding Torque for Quarter-Turn Valves

Valve producers publish torques for his or her merchandise in order that actuation and mounting hardware can be properly chosen. However, published torque values usually represent only the seating or unseating torque for a valve at its rated pressure. While เกจวัดแรงดันภาษาอังกฤษ are necessary values for reference, printed valve torques don’t account for precise set up and working characteristics. In order to find out the precise operating torque for valves, it is essential to grasp the parameters of the piping methods into which they’re put in. Factors such as installation orientation, direction of flow 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: Val-Matic
The American Water Works Association (AWWA) publishes detailed info on calculating working torques for quarter-turn valves. This info appears 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 edition. In addition to info on butterfly valves, the current version also includes working torque calculations for different quarter-turn valves together with plug valves and ball valves. Overall, this manual identifies 10 components 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. via 72-in. butterfly valves, C504, was revealed in 1958 with 25, 50 and one hundred twenty five psi strain courses. In 1966 the 50 and one hundred twenty five psi stress courses had been increased to 75 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 printed in 2010 with 25, 50, 75 and 150 psi stress classes with the 250 psi class added in 2014. The high-performance butterfly valve commonplace was revealed in 2018 and consists of 275 and 500 psi pressure courses in addition to pushing the fluid flow velocities above class B (16 toes per second) to class C (24 toes per second) and sophistication D (35 ft per second).
The first AWWA quarter-turn ball valve normal, C507, for 6-in. via 48-in. ball valves in 150, 250 and 300 psi pressure classes was published in 1973. In 2011, dimension range was elevated to 6-in. via 60-in. These valves have always 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 normal for resilient-seated cast-iron eccentric plug valves in 1991, the first a AWWA quarter-turn valve standard, C517, was not published until 2005. The 2005 measurement range was three in. through seventy two in. with a one hundred seventy five
Example butterfly valve differential stress (top) and circulate price management home 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 version. This valve is primarily utilized in wastewater service where pressures and fluid velocities are maintained at lower values.
The need 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 improvement. This standard will encompass the same one hundred fifty, 250 and 300 psi pressure classes and the same fluid velocity designation of “D” (maximum 35 ft per second) as the present C507 ball valve commonplace.
In general, all the valve sizes, circulate charges and pressures have increased since the AWWA standard’s inception.
AWWA Manual M49 identifies 10 components that affect operating torque for quarter-turn valves. These components fall into two general classes: (1) passive or friction-based components, and (2) energetic or dynamically generated components. Because valve producers can not know the actual piping system parameters when publishing torque values, printed torques are typically limited to the 5 components of passive or friction-based elements. These include:
Passive torque elements:
Seating friction torque
Packing friction torque
Hub seal friction torque
Bearing friction torque
Thrust bearing friction torque
The different 5 components are impacted by system parameters similar to valve orientation, media and circulate velocity. The parts that make up lively torque embody:
Active torque parts:
Disc weight and middle of gravity torque
Disc buoyancy torque
Eccentricity torque
Fluid dynamic torque
Hydrostatic unbalance torque
When contemplating all these varied active torque parts, it is attainable for the precise working torque to exceed the valve manufacturer’s printed torque values.
Although quarter-turn valves have been used in the waterworks business for a century, they are being uncovered to larger service strain and circulate fee service circumstances. Since the quarter-turn valve’s closure member is all the time situated within the flowing fluid, these larger service circumstances immediately impression the valve. Operation of these valves require an actuator to rotate and/or hold the closure member within the valve’s physique as it reacts to all the fluid pressures and fluid circulate dynamic circumstances.
In addition to the increased service circumstances, the valve sizes are also increasing. The dynamic circumstances of the flowing fluid have higher effect on the bigger valve sizes. Therefore, the fluid dynamic results turn into more essential than static differential pressure and friction hundreds. Valves could be leak and hydrostatically shell tested during fabrication. However, the total fluid circulate circumstances can’t be replicated earlier than site installation.
Because of the trend for elevated valve sizes and increased operating situations, it is more and more important for the system designer, operator and proprietor of quarter-turn valves to higher perceive the influence of system and fluid dynamics have on valve choice, development and use.
The AWWA Manual of Standard Practice M 49 is dedicated to the understanding of quarter-turn valves including working torque necessities, differential stress, move conditions, throttling, cavitation and system set up differences that immediately influence the operation and profitable use of quarter-turn valves in waterworks techniques.
The fourth version of M49 is being developed to incorporate the adjustments within the quarter-turn valve product standards and installed system interactions. A new chapter might be dedicated to methods of management valve sizing for fluid circulate, pressure management and throttling in waterworks service. This methodology contains explanations on using stress, flow price and cavitation graphical windows to supply the person an intensive 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 labored 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 levels 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 active 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 worked with the Electric Power Research Institute (EPRI) in the improvement of their quarter-turn valve performance prediction strategies for the nuclear power business.

Scroll to Top