OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 9 Fall Protection

Section 143 Connectors, carabiners and snap hooks

Carabiners, D-rings, O-rings, oval rings, self-locking connectors and snap hooks used to interconnect the components of a personal fall arrest system are subjected to the full maximum arresting force developed during a fall. The failure of any portion of this connecting hardware can lead to the failure of the entire fall arrest system. Carabiner users must remember that the forces stamped on the body of a carabiner represent the ultimate strength of the product, not the working load or safe working load. See Figure 9.4 for examples of carabiners.

For compliance purposes, carabiners, D-rings, O-rings, oval rings, self-locking connectors and snap hooks must bear the mark or label of a nationally accredited testing organization such as CSA, UL, SEI, etc. as evidence that the connector has been approved to the requirements of the Standards. Products bearing a CE mark also comply with this section. The CE mark – Conformité Européenne – indicates that the company manufacturing the product has met the requirements of one or more European directives. The product also complies with one or both of the listed CEN European standards.

The 2009 edition of the OHS Code marks the first time that Part 9 accepts fall protection equipment approved to standards from the U.S. and Europe. Fall protection equipment approved to any one of these standards is considered to offer an equivalent level of worker protection. Employers and workers in Alberta now have access to a broader range of equipment to safely meet their fall protection needs. Readers are referred to section 3.1 for information about previous editions of the standards.

Figure 9.4  Examples of carabiners

Carabiners and snap hooks used as interconnecting hardware in fall arrest systems must be self-closing and self-locking. This prevents unintended detachment of fall protection system components resulting from a worker forgetting to close or lock a carabiner or snap hook. For these connecting components to be acceptable for use, their gates require at least two consecutive, deliberate actions to open.

Snap hooks and carabiners that are not self-closing or self-locking cannot be used as connecting hardware in fall protection systems and must be removed from use and storage. Such components can be used in other applications that do not involve fall protection. These other applications should not allow the connectors to mistakenly make their way back into use as fall protection components. Screw gate carabiners that rely on the user to twist a collar across the gate opening cannot be used in personal fall arrest systems.

The other reason for having this self-closing, self-locking requirement is to prevent “roll-out” (see Figure 9.5). When a force is applied on the top of a non-locking gate, the gate opens, releasing the mating hardware. The most typical roll-outs have been known to occur between snap hooks and D-rings. Although no manufacturer in North America or Europe uses non-locking snap hooks anymore, thousands of them may still be in service. Employers must remove this equipment from use and storage if it is used or could be used for fall protection.

Figure 9.5 Example of accidental roll-out of a snap hook

False connection

Connecting components can create a serious hazard when they engage improperly or incompletely. Such a hazard is possible when the internal dimensions of the D-ring of the full body harness or body belt are very close to the external dimensions of the snap hook being connected to it (see Figure 9. 6).

A false connection relies on a friction fit between the two closely dimensioned components. The worker thinks that the components are properly connected while in fact the snap hook only sits inside the D-ring. This improper or incomplete connection – unseen by the worker if it involves the D-ring on the worker’s back – is unsafe and likely to come apart during the arrest of a fall or sudden jerk on a travel restraint system.

Figure 9.6 Example of improper or incomplete connection

Gate cross-loading

Snap hooks and carabiners are designed to handle maximum loads in line with their long axes. However, because of their shape or circumstances of use e.g. loops of webbing or rope coming to rest across the gate and then being placed under tension, snap hooks and carabiners can be subjected to gate cross-loading, resulting in much lower breaking strengths (see Figure 9.7). Connections between hardware components must be made carefully when using snap hooks and especially carabiners.

Figure 9.7 Example of cross-loading a carabiner gate

Compatibility of materials

Workers need to be aware that aluminum carabiners and snap hooks should not be connected directly to wire rope and slid along the rope’s length. Being softer than steel, aluminum wears and the carabiner or snap hook loses some of its strength. Steel carabiners or snap hooks should be used in such cases. Manufacturers of horizontal lifelines commonly provide special steel rings or rollers into which a safe, non-wearing connection can be made.