Large fans broke and pieces fell onto worksite
Date of incident: April 2022
Notice of incident number: 2022169730037
Employers: Concrete and cement manufacturer; industrial maintenance contractor
Incident summary
At a cement production plant, workers had removed and then reinstalled sections of guarding on the fans on a large heat exchanger as part of a month-long maintenance shutdown. The guarding on each fan was made up of several pie-shaped sections of metal that were bolted together and bolted onto the housing of the fan. A few days after the equipment at the plant was restarted, two of the fans started automatically in response to a temperature increase. Shortly after they started, the two fans failed. Some of the fan blades broke and pieces of the fan blades were expelled from the fan housing. No workers were injured.
Investigation conclusions
Cause
- Inadequately secured fan guarding entered fans. When the two fans on the heat exchanger activated, sections of the guarding for the fans fell or were drawn into the fan blades because they were inadequately secured following preventive maintenance activities. This caused the fans to fail, and pieces of the fan blades fell to the ground.
Contributing factors
- Inadequate quality control and quality assurance. The maintenance contractor did not ensure that its workers had adequately completed the assigned work. The cement plant did not take adequate steps to ensure that all of the bolts were secure and guarding was properly in place before starting up the equipment, as required by the equipment manufacturer. The manual for the heat exchanger included a requirement to check and tighten all bolts and to properly secure all safety guards. The cement plant did not take adequate steps to ensure that these requirements were met before restarting operations.
- Lack of preventive maintenance program. The cement plant did not have a documented preventive maintenance program for the heat exchanger. The lack of a documented maintenance program increased the risk that items would be missed when performing preventive maintenance activities.