Case Study 4:
Chemical Drum Handling
The operation analyzed was a manufacturing step which involved the manual transfer of materials into a kneader for processing. The original process involved the manual handling of drums, bags, and pails associated with the addition of powders and liquid into the kneader for mixing. The process of weighing out powder and liquid to blend in the kneader was labor intensive and also introduced process fluctuations due to the variability of material mixed caused by manual dispensing.
The company is considered a world leader in the prevention of injuries and illness. As part of their safety management system, workplace risk assessments identified the operation as having the potential to cause ergonomic injuries and/or illnesses due to the routine handling of drums, bags, and pails of various weights. The open handling also introduced exposure to low-toxicity dusts, which required air-purifying respirators to be worn.
The intervention involved the design and installation of an automated system to add liquids and powder to the kneader. This design eliminated the manual handling of powders using bags, pails, and scoops at the filling stage. The project included the installation of lifting devices to handle drums at raw material and finished product loading and unloading stations. It also reduced airborne dust exposures that eliminated the need for employees to wear respiratory protective equipment (RPE).
Impacts of the Intervention
The intervention significantly reduced the ergonomic exposure associated with the routine handing of drums, bags, and pails. The company estimated that the intervention would normally eliminate one serious injury over a 10-year period. However, the operation is in a country with very liberal laws regarding injury/illness reporting and disability and as such it is likely that the intervention could achieve even greater cost reductions associated with fewer injuries being incurred. The intervention also enclosed the transfer operation resulting in a more efficient containment of dusts and eliminating the need for RPE at this manufacturing stage.
The intervention also resulted in a significant productivity improvement resulting in one less person needed to operate the kneader process. During the project implementation, a scale was incorporated into the closed transfer process thus allowing more accurate liquid addition and reducing the variability of the quality of the final product.
A financial analysis of the intervention showed a 5-year net present value (NPV) of $39,708 with an internal rate of return (IRR) of 32%. This scenario assumed that if the intervention had not been undertaken, one serious ergonomic injury would have occurred during the 5-year period. The company uses an internal cost of $40,000 per ergonomic injury/illness. A second scenario that assumed no injury would occur yielded an NPV of $24,160 with an IRR of 25%. Both scenarios resulted in a discounted payback period (DPP) of 3.1 years.
Facility management recognized the ergonomic risk associated with the routine manual handling of drums involved in this production operation. From a financial viewpoint, it was hard to determine future health and safety benefits associated with the project other than to project that a serious ergonomic injury was likely during the next 5 years. However, the productivity improvement associated with the more efficient handling of drums and the transfer of product were the financial drivers to justify the project. Improvement in operator health and safety, along with improved product quality, were intangible benefits. This project demonstrated that health and safety consequences should be considered when work systems are designed or retrofitted to ensure the benefits to the organization are optimized.