OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 6 Cranes, Hoists and Lifting Devices

Section 92.1 Load blocks

Load blocks are assemblies that consist of a hook or shackle, swivel, bearing, sheaves, sprockets, pins and frame. They are suspended by a hoisting rope or load chain and are designed for a variety of lifting applications.

Inspection, maintenance and repair requirements are typically specified by the manufacturer. Where such specifications exist, an employer is obliged, under this section, to follow them. If there are no manufacturer’s specifications, an employer must follow the requirements of CSA Standard CAN/CSA Z150-98 (R2004) which states in Clause

“Teardown inspection and relubrication of the swivel, hook, and block assembly shall be performed at least every five years and the hooknut shall be disassembled and inspected for corrosion and wear. The hooknut shall be relubricated with a high-pressure grease of medium consistency, to seal the assembly from moisture, or with molybdenum disulphide grease or another sacrificial lubricant possessing the same physical characteristics. The hooknut assembly shall be durably marked to indicate the date of inspection.”

In a recent British Columbia incident, a tower crane was hoisting a load weighing approximately 4000 kgs. The hook assembly on the load block failed, causing the load to fall. In the investigation, the threads on the hook and nut were found to be corroded and excessively worn. The damage was not visible when the load block was assembled. This type of wear and corrosion could be found on any crane hook with a threaded shank.