Alert: Davit arm system failure
Learn about the risks of using a davit arm system to support suspended work platforms and the importance of its inspection and particularly its welds.
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This is an alert to building owners, employers and workers who use a davit arm system to support suspended work platforms.
This davit system is part of the “supporting structure” for boatswain’s chairs and elevating/suspended work platforms and their attachments, which are used extensively in window washing and building facade repair work operations.
The Ministry of Labour, Training and Skills Development is aware of an incident where an aluminium davit arm collapsed while the system was hoisting a suspended work platform with two workers. The platform was only four feet above ground level at the time of the collapse. None of the workers sustained injury.
This davit arm system that failed in this situation was manufactured in 1990. It was installed on the roof of the building for the purpose of window cleaning operations. A competent person visually inspected the system during the annual anchor inspection, as required by Section 41 of Ontario Regulation 859 for Window Cleaning. The inspection report did not identify any deficiency in the davit arm system.
The Ministry of Labour, Training and Skills Development’s incident investigation found that the welds which connected the beams to the shoulder collar were the likely cause of this accident. A further investigation by welding specialists found the existing welds to be deficient and that they failed to support the structural loads applied to the system during hoisting of the suspended work platform.
The Ministry of Labour, Training and Skills Development’s investigation team also learned that a similar davit arm failure contributed in the death of a worker in the City of Montreal. The cause of that failure was due to "deficient welds".
All buildings where window-washing operations and building facade repair are carried out using elevating/suspended work platforms and boatswain’s chairs that are suspended by a davit system.
It is recommended that owners of buildings where davit systems are installed on the roof conduct the following before commencing window washing or building facade repair work.
- Have the davit arm system inspected and verified by a competent person or a professional engineer to ensure that the system can support the loads applied to it;
- Have the welds inspected to ensure structural integrity and conformance with CSA Standards Z271-98 Article 5.4.1 (welding of steel) and Z271-98 Article 5.4.2 (welding of aluminium).
- If the welds or other component of the system is defective, withdraw the system from service and do not use it until the appropriate corrective action is taken.
All workplace parties, including the building owner, should be aware of the requirements under Ontario Regulation 859 with regard to window cleaning. The following provisions in the regulation have particular relevance to this situation:
41. (1) The owner of a building mentioned in section 39 or 40 shall cause all anchor points and permanently-installed suspended scaffolds to be inspected by a competent person,
(a) before being used for the first time;
(b) thereafter as often as necessary but not less frequently than recommended by the manufacturer of the anchor points or the suspended scaffolds, as the case may be and, in any case, at least once a year; and
(c) when informed under section 43.
(2) Maintenance and repairs of a permanently-installed suspended scaffold shall be performed in accordance with the manufacturer's instructions.
(3) The competent person making the inspection required by subsection (1) shall immediately upon completion of the inspection report to the building owner any defects or hazardous conditions detected in the anchor points and any permanently-installed suspended scaffold.
(4) A building owner shall ensure that any faulty anchor point is repaired and is suitable for use for window cleaning and sill work before being used.
(5) A building owner shall keep a record of the inspections of any anchor points and any permanently-installed suspended scaffold at a building in a log book to be maintained and retained as long as the anchor points and suspended scaffold are used, showing,
(a) the date on which each inspection is made;
(b) the name and signature of the person making the inspection; and
(c) any modifications or repairs made to an anchor point or a suspended scaffold, including the date they are made and the name and signature of the person making the modifications or repairs.
43. If an employer, supervisor or worker believes that any anchor point or related structure that is used to support a suspended scaffold, suspended work platform, boatswain's chair, similar single-point suspension equipment or lifeline is defective or inadequate, the employer, supervisor or worker shall inform the building owner of this fact immediately.
This resource does not replace the Occupational Health and Safety Act (OHSA) and its regulations and should not be used as or considered legal advice. Health and safety inspectors apply and enforce these laws based on the facts they find in the workplace.