Workplace Health and Safety Queensland recently issued a health and safety alert highlighting the risks of falling overhead building services caused by the failure of insert anchors in overhead building services such as air conditioning ducts, cable trays, water pipes and waste pipes.
The alert was issued following two separate incidents in late 2018 which occurred involving insert anchors.
Insert anchors are also known as post-installed anchors and use a number of installation methods including the use of a hammer, cordless drill/driver or torque wrench.
In the first incident, a large air conditioning duct, suspended from the underside of a suspended concrete slab, dropped to the floor below. The anchors were loaded in direct tension (pull out) and failed.
In this incident cheap ‘hammer in’ type insert anchors were used. The anchor manufacturer clearly states that the anchors were unsuitable for an overhead application.
In the second incident, a 70-metre-long cable tray holding heavy electric cable pulled away from a concrete wall and injured workers next to the cable tray.
The cable tray was supported by a combination of threaded rods from above and cantilevered brackets that were fixed to the wall using screw bolt type insert anchors.
The failure of insert anchors can be caused by a number of factors including:
The alert noted that most of the larger manufacturers of post-installed anchors produce a range of anchors of differing quality for a broad range of applications.
Many of the cheaper and smaller anchors are not intended for applications where the failure of the anchor can cause death or injury.
Wherever the manufacturer states that certain applications are unacceptable, these instructions must be complied with.
To reduce the likelihood of failure of insert anchors used to support overhead services the alert said to ensure: