Ergonomic Evaluation of Scaffolding Task Interventions for Power Plant Maintenance

scaffolding;ergonomics;industrial engineering

Diering, Matthew ; David B. Kaber, Committee Co-Chair,Jeff Thompson, Committee Member,Yuan-Shin Lee, Committee Member,Simon Hsiang, Committee Member,Diering, Matthew ; David B. Kaber ; Committee Co-Chair ; Jeff Thompson ; Committee Member ; Yuan-Shin Lee ; Committee Member ; Simon Hsiang ; Committee Member

University:North Carolina State University

关键词: scaffolding;    ergonomics;    industrial engineering;   

Others  :  https://repository.lib.ncsu.edu/bitstream/handle/1840.16/1034/etd.pdf?sequence=1&isAllowed=y

美国|英语

来源: null

【 摘 要 】

A nuclear power plant is a complex operation requiring a large number of maintenance operations. Examination of a local power utility’s injury database revealed that maintenance personnel had the highest injury incidence rates. Maintenance jobs were analyzed from an ergonomics perspective and scaffolding tasks, including walk-board tie-down to frames and frame tube coupling, were found to pose high risks. Ergonomic risks included excessive torques at joints and awkward posture positions in both tasks. The purpose of this research was to conceptualize interventions to reduce these risks and to conduct experiments to empirically assess the impact of the proposed interventions on worker posture and performance.The standard procedure for walk-board tie-down at the nuclear power plants calls for the use of #9 gauge wire. The wire is looped around a walk-board and a scaffolding tube, and then twisted with pliers to tighten. The ergonomic analysis showed that this task involved extreme wrist posture positions with high rotational forces. To alleviate these problems, the replacement of wire tie-downs with plastic zip ties was proposed.In scaffold frame assembly, tubes are clamped together using right-angle and swivel couplers. To tighten a standard coupler a nut and bolt mechanism is ratcheted. The ergonomics analysis showed that this task required very high torques to be applied to the ratchet. A coupler utilizing a “ski-boot†-type clamping mechanism was designed to eliminate the repetitive ratcheting motion and the excessive torque requirements.Two experiments were conducted to test the interventions using electro-goniometers to record wrist angle measurements. The tie-down experiment recorded wrist flexion, extension, radial deviation, ulnar deviation and the average task-to-time completion (TTC). The coupling experiment measured wrist flexion, extension, radial deviation, ulnar deviation, forearm pronation and the average TTC. Multivariate and univariate Analyses of Variance were conducted on each response measure to assess the impact of each intervention. It was expected that the zip ties and lever-based coupler would significantly reduce wrist joint angles as well as TTC. By replacing the wire ties with more flexible plastic zip ties, angular response measures and TTC were positively affected. Maximum flexion angle was reduced by 37%, maximum extension angle was decreased by 4.0% and maximum ulnar deviation angle was decreased by 17.0%. While there was no reduction in radial deviation solely due to the plastic zip ties, a decrease was seen during certain subtasks (tie-down/tightening). TTC was reduced by 1.6 seconds when using the plastic zip ties. It was recommended that plastic zip ties replace the #9 gauge wire for the walk-board tie-down task.Results of the coupling experiment revealed coupler type to interact with the subtask being performed (i.e., coupler placement/removal or tightening/loosening) to effect the angular response measures. Due to the elimination of the ratcheting task, a 9.0% decrease in maximum flexion was achieved while there was no effect on maximum extension angle. A 19.5% decrease in maximum radial deviation angle and a 6.6% decrease in maximum ulnar deviation angle were found when tightening the lever couplers. There was no significant reduction in forearm pronation. While there was reduction in the angular response measures, the lever coupler was found to slightly increase the TTC for frame tube coupling (approximately 12%) as compared to the ratcheting couplers. Based on the improvement in the angular response measures, the lever couplers were recommended for further examination as a viable alternative to the standard scaffolding couplers. An avenue of future research would be a comparison of the force requirements for the existing couplers versus the lever couplers.