July 20, 2020
WorkCover Queensland has issued a safety alert following an incident in May in which a farmer was injured by a collapsing transportable silo.
The 5m high grain silo collapsed while the farmer was underneath it.
According to WorkCover, it appeared the support framework buckled on one side of the silo, causing the body of the silo to topple sideways on to the ground.
The impact caused the skin of the silo to tear away from the silo base, spilling grain.
The farmer was trapped for some time until he could be removed. As well as being severely injured, there was also a risk of the farmer being suffocated as the grain emptied from the ruptured silo.
WorkCover said the cause of the failure was still being investigated and it had not been determined so far why the support framework failed.
However, support frames on silos could fail for one or more of the following factors:
- Damage, including bent support members and broken welds. Bending not only reduces the load carrying capacity of a member but can also increase the load applied to that member because it can cause the silo to tilt, therefore moving the centre of gravity closer above the member.
- Impact from mobile plant. This can cause immediate collapse or can bend support members so that failure can occur later.
- Corrosion, either external or internal. Internal corrosion can occur when hollow members fill with water, even with small cavities in the member and no drainage holes. External corrosion can occur when the protective coating degrades or when parts of the support frame are buried in dirt.
- Soft or sloping ground under the silo can cause the silo to tilt, making the silo unstable and increasing the load on some of the support members.
- Poor design and/or manufacture.
- Poor repairs.
Transportable silos were generally designed to be lightweight to allow easy movement. This characteristic meant that this type of silo can be blown over when it was empty and not anchored to the ground or support pad.
WorkCover said silos should always be set up in accordance with the manufacturer’s instructions and silos with damaged support frames should be isolated from workers.
- External link: Transportable Silo Safety Alert
