introduction: One of the most common causes of occupational injuries in industrialized and developing countries is musculoskeletal disorders Determining the risk factors of musculoskeletal disorders can be helpful choosing the right method for interventions and detailed studies. This study aimed to evaluate the ergonomic risk factors in operators of pressurized irrigation equipment factory.

Materials and Methods: This cross-sectional study was conducted in a pressurized irrigation equipment manufacturing company. In this study, a new method based on observation was used to evaluate the ergonomic aspects of operator's activity. In order to assign tasks and sub-tasks, direct observation and video recording equipment were used. Ergonomic assessment was carried out on all sub-tasks identified. then, the criticality of the task determined.

Results: Among the tasks identified 53 very critical posture 61 critical and 82 low critical posture was determined. Ergonomic point in the ball valve production line was 0.6 and 0.68 respectively for tow operator. For drop valve and automatic valve production line's ergonomic point was 0.52 and 0.67 respectively.

Conclusion: According to the results, posture analysis method used in this study is easy and accurate. The advantage of this method is 14 ergonomic domaines that covered whole body and time fragment of each task. Findings of previous studies showed good correlation between results from this method and OCRA method.

In this study, The most critical posture was related to operator's wrist, so it is recommended that control measures on wrist posture correction should be considered.