In valve operations, particularly with underground valves of uncertain characteristics, the critical issue of aligning an actuator's torque capabilities with the Maximum Allowable Stem Torque (MAST) of the valve is frequently neglected.
This oversight may appear minor, yet it significantly impacts the smooth and safe operation of industrial valves management.
Manual valves can become stuck, requiring more torque than can be applied by hand.
In such cases, users can increase the torque applied by using a longer handle or a wrench. When designing any valve that will require a significant amount of torque to operate, data study indicates that larger wheels should be used. The torque produced by a force is increased with a greater moment arm.
Giving an example of manually operating valves using F-keys or bars can be time-consuming, labor-intensive, and risky, depending on factors like valve size and condition. Risks include:
✔️Over-tightening: F-keys may apply excessive torque, risking damage to valve components by exceeding MAST limits.
✔️Lack of Feedback: F-keys offer no torque feedback, hindering operators from accurately assessing MAST limits and valve integrity.
✔️Lack of Measurement: F-keys lack torque measurement, making it difficult to ensure torque remains within MAST limits, crucial for assessing valve condition and maintenance needs.
Before assessing the advantages of Portable Valve Actuators, let us have a look into the example for valves in water supply:
Torque is the force required to turn a valve stem, either opening or closing the valve. Estimating the correct torque is crucial for selecting the appropriate actuator for a valve system.
Breaking Torque: The minimum push force required to open the valve against flow and pressure, necessitating an actuator release mechanism capable of specifying this minimum.
Running (Dynamic) Torque: The torque applied during motion against joint friction, determining the angle the actuator's pivot settles on, crucial for variable designs.
End to close torque: The minimum retrograde force needed to reset the ball valve to the closed position, which may differ significantly from Breaking Torque due to active flow within the valve.
✔️Insufficient torque: If an actuator lacks the necessary force to turn the valve stem, the valve won’t fully open and may get stuck halfway.
✔️Excessive torque: Too much force can damage both the valve and the system.
Different valve types have distinct torque requirements based on their application, design, and purpose:
✔️Butterfly valves: Require significant turning force to open or close but minimal force for flow throttling.
✔️Ball valves with metal seats: Demand substantial turning force due to high-friction metal-to-metal contact.
✔️Control valves: Typically need more torque than simple on-off valves. They operate within varying flow and pressure conditions, necessitating precise control.
💡If the valve has a gearbox, the reduction ratio must be taken into account when calculating the required torque.
Maximum Allowable Stem Torque (MAST) is the maximum torque or thrust that can be applied to a valve without risking damage, as specified by the valve manufacturer or supplier.
It encompasses all parts of the valve drive between the operator and the closure member, excluding the valve operator itself (e.g., gearbox or actuator).
The actuator, responsible for valve movement (opening or closing), must not exceed the valve’s MAST at any point during travel.
This applies to both manual and actuated valves.
When using manual actuators (such as PVA’s or gearboxes), the concern about exceeding MAST is generally less pronounced due to lower torque levels.
Manual quarter-turn valves are commonly used in applications where power is unavailable or where fail-safe mechanisms are desired. In such cases, users may wish to increase the torque by using a longer handle or a wrench.
A portable valve actuator is a versatile tool that can be highly effective in opening or unjamming valves in various industrial settings. Valves can sometimes become jammed or stuck due to various reasons, including rust, corrosion, debris buildup, mechanical failure, or other issues.
Hereby are some benefits of using Portable Valve Actuator :
🔵Safety Assurance: Torque plays a crucial role in ensuring operator safety during manual valve operations. The ability to swiftly open or close valves directly in critical situations is essential for risk mitigation.
🔵Efficiency Enhancement: Portable actuators enhance manual operations by providing efficiency and flexibility. Their quick setup and precise handling capabilities enable rapid response to emergencies.
🔵Adaptability and Flexibility: While automation offers efficiency, manual operations provide adaptability. Portable actuators extend the operator's range of action, allowing for quick adjustments and fine-tuning as per changing requirements.
🔵Maintenance and Diagnostics: Regular maintenance is vital for asset management. Manual valve operations, coupled with portable actuators, facilitate direct visual inspections, aiding in the detection of potential problems or damage.
🔵Tactile Feedback: Manual operations enable operators to rely on tactile skills and receive direct sensory feedback, ensuring quick and accurate responses to operating conditions. Portable actuators maintain this sensory connection while eliminating the need for physical effort.
💡You should also consider the maximum torque your valve and/or its handwheel will allow to ensure that the maximum torque developed by the actuator will not exceed the permissible torque. If this is the case, consider the "torque limiter" option available on most of our units.
Efficient and reliable valve performance hinges on proper torque management. On the other hand, failure to align actuator torque capabilities with MAST specifications can lead to operational disruptions and increased maintenance costs for industrial valve systems.
As a manufacturer of portable valve actuators, we maintain close communication with engineers and operators in the field, and that allow us to stay attuned to their main concerns .
By fostering ongoing dialogue and collaboration, we gain valuable insights into the challenges and preoccupations faced by these industrials in various applications.
Our proactive engagement enables us to address their specific needs and preferences when designing and developing portable valve actuators. Whether it's ensuring compatibility with different valve types, addressing concerns about torque requirements and safety factors, or providing practical solutions for manual valve operation, we strive to offer tailored solutions that meet the demands of real-world applications.
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