In North America, ensuring worker safety during rigging operations in the construction sector is of paramount importance. This involves adherence to a set of regulations and best practices that govern the safe use of rigging equipment. The factor of safety, also known as design factor, must be incorporated into the design capacity of all rigging components, while the sling-angle reduction factor is another impacting element for rigging capacity.
This article provides a brief overview of these two factors as outlined in Canadian and United States regulations and explains how MTC Solutions applies these standards to recommend safe capacities for all its rigging products.
Approximately 6-minute read.
The factor of safety, or design factor in Canada, is a fundamental principle that underpins the safe operation of rigging equipment. It represents the ratio of the breaking strength of the rigging equipment over the working load limit (WLL) to provide a margin of safety for situations of unintended overloading. As long as the WLL is respected, the workers can trust the equipment used in the hitch.
Similarly, the sling-angle reduction factor is another essential consideration in rigging safety. This factor adjusts the WLL based on the sling angle, that is, the acute angle between the sling and the construction element. As this angle deviates from vertical (90°), the tension on the sling increases due to a horizontal load component, thereby reducing the overall capacity of the system.
Canadian Regulations
In Canada, occupational health and safety requirements for construction are generally established and enforced at the provincial or territorial level. Each jurisdiction establishes its own legislation and safety regulations applicable to construction and rigging operations. For example, Ontario, Quebec, British Columbia, and Alberta—the four most populous provinces—maintain their own occupational health and safety requirements.
Applicable safety requirements vary by jurisdiction, and rigging operations should follow the safety regulations in effect for the province or territory where the work is performed.
MTC Solutions incorporates a 5:1 factor of safety into the design values of its rigging systems. Applicable safety factors and requirements should be verified against the regulations governing the project jurisdiction.
For example, British Columbia’s regulations specify that the WLL of a rigging system is reduced to 90%, 70%, and 50% of its maximum value at vertical when the sling angle falls within the ranges of [60°, 90°), [45°, 60°), and [30°, 45°), respectively. Sling angles less than 30° are prohibited unless part of an engineered lift. TSling-angle requirements and any associated capacity reductions should be verified against the applicable safety regulations for the project jurisdiction.
Figure 1. Relationship between Sling Angle and WLL
United States Regulations
In the United States, the Occupational Safety and Health Administration (OSHA) is the federal agency responsible for establishing rigging regulations, which are aligned with the ASME B30 standard. Similar to Canadian regulations, OSHA sets the factor of safety for all rigging components to 5:1. While there are no clear stipulations for the sling-angle reduction factor in OSHA’s guidelines, its universal applicability remains relevant.
MTC Solutions Rigging Systems
In our Rigging Design Guide, we determine the safe capacities for our various rigging systems based on thorough mechanical testing and fastener strengths detailed in ICC-ESR 3178 and 3179. We follow the specific methodology described in Section 12.3 of NDS. These design values incorporate a factor of safety of 5:1, along with other adjustment factors, and are recommended for rigging scenarios where the sling angle is 60° or greater.
It is crucial to strictly follow safety rules specific to your location when rigging construction materials, including those made with mass timber. Licensed rigging professionals and site supervisors must ensure that the rigging equipment used has a factor of safety of at least 5:1. It is important to make sure that this factor of safety is included in the design capacity of the anchoring devices. If not, the design capacities must be adjusted accordingly. Other factors, like the sling-angle reduction factor, may also need consideration to ensure safety. Adhering to proper rigging practices is essential for a safe working environment and to minimize the risk of on-site injuries.
If you have any questions about our rigging systems or need help with rigging planning, contact our Technical Support Team. 😉
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