Mineral Mines & Quarries Inspectorate | Alert | No.414 V 1 | 26 July 2022
Hauling equipment failure during conveyor belt change out
A 14mm synthetic fibre rope failed when the breaking strain was exceeded during installation of a new conveyor belt. When the rope failed it whiplashed, striking a worker in the face. As a result of the accident, the worker later had surgery to remove one of his eyes.
How did it happen?
A loader was being used to replace an old conveyor belt at a crushing and screening plant. One end of the rope was attached to the loader and the other attached to the old conveyor belt to be removed. The loader was providing the motive force to pull the old conveyor belt off the conveyor structure. During the process of removing the old conveyor belt, a gravity take-up unit pulley jammed when the links of a safety chain used to lift it became stuck between the pulley end and the adjacent structure. This increased the force needed to move the conveyor belt, resulting in the rope failure.
- An exclusion zone had not been defined to account for rope or cable stretch under load. Equipment failure during hauling and loading type operations can occur at any stage. Workers need to be aware of this and stay well clear of items such as cables, ropes, and chains when they are under tension.
- Purpose-built equipment such as a winch, winder or reeler was not used when replacing the conveyor belt.
- Personnel working in the area were not wearing appropriate PPE to protect them from flying materials or objects.
Separation – The most critical control in this instance is separation from the hazard. An exclusion zone should be implemented when using cable, ropes, or similar types of haulage equipment under tension. The exclusion zone should account for any rope or cable stretch under load, plus a significant allowance as a margin of safety, particularly when using synthetic fibre ropes. The exclusion zone must be clearly defined and, where possible, physically prevent entry into the exclusion zone.
Substitution – Preference should be given to purpose-built equipment such as winches, winders and reelers when installing or replacing conveyor belts. This type of equipment allows for a more controlled belt pull on process and can be operated by personnel at a safe distance. Winches may be fitted with load cells to ensure wire cable breaking strain is not exceeded.
Substitution – Some traditional synthetic fibre ropes such as nylon and polypropylene are particularly prone to whiplash or failure due to their elasticity. Newer synthetics such as HMPE (high modulus polyethylene) and natural fibre ropes can mitigate this problem. Natural fibre ropes are more prone to degradation however, particularly when subjected to wet and muddy conditions over time. Ropes should be checked and replaced on a regular basis.
Engineering – Belt pull calculations should be carried out prior to a belt installation to determine the correct rated capacity of haulage equipment. Wireless load cells are now available to ensure breaking strain of haulage equipment is not exceeded whilst workers remain safely outside of the exclusion zone. Load cells can also help detect an abnormal condition during belt haulage activities, prompting an inspection of jam and wedge points.
Engineering – Winch line dampeners are effective at reducing rope lash on failure, provided they are used as per manufacturer’s instructions (i.e. filled with sand or dirt to increase their dampening effect).
Administrative – Safe work instructions related to conveyor installation or replacement should be reviewed to ensure the risk of catastrophic equipment failure is identified and appropriate controls are in place.
Personal Protective Equipment – As a last line of defence, eye protection should be worn when carrying out tasks where there is a risk from flying material or objects.
Note: The critical control 'separation' must be implemented irrespective of other controls being considered.
Investigations are ongoing and further information may be published as it becomes available. The information in this publication is what is known at the time of writing.
We issue Safety Notices to draw attention to the occurrence of a serious incident, raise awareness of risks, and prompt assessment of your existing controls.
Contact: Paul Heritage, Inspector of Mines , 0436 627 749 QldMinesInspectorate@rshq.qld.gov.au
Issued by Resources Safety & Health Queensland
Placement: Place this announcement on noticeboards and ensure all relevant people in your organisation receive a copy, understand the content, findings and recommendations as applicable to their operation. SSEs should validate that recommendations have been implemented.