Recently, Xcel Energy, a large energy company in the United States, selected the Sofis Power Wrench portable actuator as a tool to combat fatigue in manual valve operations. The decision to use the Power Wrench portable actuators was based on an evaluation carried out by a committee of engineers, ergonomic specialists, and operators to address operational, worker-centric process safety principles.
Worker-centric process safety management
Worker-centric process safety management (PSM) is a new approach to PSM that works to make systems, procedures, and tasks suited to the physical and psychological needs of humans. Just as ergonomics is the field of suiting equipment to the worker, instead of the other way around, worker-centric PSM seeks to remove error traps, inefficiencies in workflow, confusing procedures, and building plants to keep people safe, instead of relying on people to keep the plants safe.
Error traps and drivers of error
Worker-centric PSM seeks to avoid or eliminate so-called ‘error traps’, which are circumstances that can increase the risk of an accident. Error traps make it more difficult to work safely and increase the likelihood of errors. When combined with humans’ innate tendencies, they create a likely opportunity for error to occur. Specific circumstances or ways of working can produce an environment conducive to human error. These are called ‘drivers of error’. Fatigue is an important driver of error.
Fatigue is an important driver of error
Physical fatigue contributes to making mistakes, as the worker is excessively distracted by the discomfort of the environment, or the strain necessary to perform the task. This can lead to error because the worker is more focused on how to perform part of a task than anything else and increases the risk of injury to the worker as well as the equipment.
Power Wrench helps combat fatigue
As a result of the evaluation, Xcel Energy considered the strategic use of equipment to overcome fatigue and physical operator stress during manual valve operations. A specific operation involved a valve on a newly constructed high-pressure valve set that required ~220 revolutions to actuate and often required actuation multiple times per day. Manual operation of large valves induces strained or fatigued arms, hands, shoulders, and backs, increasing the risk of injury and missed days of work. An on-site demonstration of the Power Wrench portable actuator found that using the Power Wrench allowed operators to operate these valves safely and quickly, reducing stress on the operators.
Green and Yellow Zone guidelines
The Power Wrench conformed to the ‘green and yellow zone’ work guidelines of the gas company, as the weight of the 22lb (10 kg) tool is supported by tension pins on the universal drive plate. These details further improve the worker-centric nature of the Power Wrench.
Truck-mounted air compressor for use in remote valve location
Due to the relative remoteness of the valve location, a compressed air supply or ‘plant air’ was not available on site. Instead, the Power Wrench was tested with two different truck-mounted air compressor units and performed well with both. This demonstrates the wide range of applications the Power Wrench can service, due to the universal availability and safety of compressed air.
Incorporation in standard design practice
Xcel Energy has recommended the Power Wrench as a standard tool for valve maintenance in all future capital projects and incorporated the Power Wrench into standard design practice recommendations.