Solution Summary: Alternative Stud Welding System
The alternative stud welding system is an engineering control that may help reduce low back injuries by eliminating prolonged stooped postures used during conventional stud welding. The alternative stud welding system uses a mobile cart with an articulating arm. Standard accessories found on a conventional stud welding gun (e.g., the chuck, foot and ferrule holder) can be mounted to the articulating arm.
The alternative stud welding system requires two workers to operate the stud welding cart, the first to move and load the studs, and the second to load studs into articulating arm to place and weld studs (Figure 1). The stud loader chute is available in various configurations to accommodate different sized studs. The cart for the system weighs approximately 175 lbs and has a footbrake to keep the cart stable during stud welding. Workers can remain standing during stud welding tasks (Figure 2).
Figure 1. Two workers operating and alternative stud welder cart.
Figure 2. Stud welder demonstrating tasks being completed from standing.
Conventional shear stud welding requires welders to maintain a stooped posture and perform stressful hand and wrist activities to place and weld shear studs to structural steel. Stooped postures can cause low back disorders, such as muscle strain or a disc herniation (“slipped disc”), which is bulging of disc material possibly pressing on the spinal cord or nerves that go into the leg. The alternative stud welding system may reduce stooped postures because it allows the worker to stand upright when shear studs are placed and welded. This reduces stress on low back muscles which may reduce risk of injury.
Stressful hand and wrist activities can cause muscle strains; tendonitis, which is inflammation of elbow and wrist tendons; or carpal tunnel syndrome, which is compression of a wrist nerve, resulting in finger numbness and loss of hand strength. The alternative stud welding system may reduce stressful hand and wrist activity because the welding gun requires minimal force to operate and is attached to a mobile cart eliminating the need for workers to carry the welding gun.
How Risks are Reduced:
The alternative stud welding system allows welding of shear studs to be done while standing in a more upright position. The articulating arm’s operating handle is at chest level eliminating the need to bend over while stud welding. Additionally, the articulating arm requires minimal force to operate and is attached to the mobile cart so workers do not need to carry the welding gun.
Independent researchers performed a study comparing the alternative stud welding system to the conventional stud welding process (Fethke et al. 2010). Researchers found that the alternative stud welding system greatly improved working posture compared to conventional stud welding methods. Independent studies have associated the time a worker spends stooping and the incidence of back pain (Hoogendoorn et al., 2000).
The manufacturer states the alternative, “stud welding method has been designed around the needs of the human body while maximizing the efficiency of the entire process.” The manufacturer also states “through our innovative designs in technology, and ergonomics we’ve created a way to help reduce work related injuries inherent in stud welding.”
Safety and health experts believe that reducing the amount of time a worker spends in a stooped posture may reduce the risk of low back injuries. The alternative stud welding system minimizes stooped postures from the stud welding process.
Effects on Productivity:
The alternative stud welding system may increase productivity by reducing worker fatigue during stud welding.
Transportation of the stud welding cart can be performed with a common work truck. The cart has attachments for crane hooks to transport the cart to jobsites inaccessible to vehicles or from floor to floor in a weld-through decking application.
It is necessary to occasionally lift the cart across girders. These lifts are easily done with two workers and the cart can be shuffled across girders instead.
Dan Anton, PT, PhD, ATC; and Jonathan Braun, SPT – Eastern Washington University