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820 Cranes and Derricks Safety I
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Working Under the Boom, Jib, or Other Components

When pins (or similar devices) are being removed, employees must not be under the boom, jib, or other components, unless site constraints require one or more employees to be in such a position. In such a case, the A/D director must implement procedures that minimize the risk of unintended dangerous movement and minimize the duration and extent of exposure under the boom.

Real World Example

A crew of ironworkers and a crane operator were unloading a 20-ton steel slab from a low-boy trailer using a 50-ton crawler crane with a 90-foot lattice boom. The operator was inexperienced on this crane and did not know the length of the boom. Further, no one had determined the load radius. During lifting, the load moved forward and to the right, placing a twisting force on the boom. The boom twisted under the load, swinging down, under and to the right. Two crew members standing 30 feet away apparently saw the boom begin to swing, and ran. The boom struck one of the ironworkers in the head, causing instant death. Wire rope struck a management-trainee and caused internal injuries. He died two hours later at a local hospital.

Knowledge Check Choose the best answer for the question.

3-6. When must employees not be allowed under the boom, jib, or other crane components?