Cranes, Derricks, Hoists, and Rigging Safety Flashcards

The 'two-block' condition in crane operations occurs when:

Answer: The load block contacts the boom tip, potentially causing a crane failure

Two-blocking occurs when the load block rises and contacts the upper load block or boom tip, which can cause wire rope failure or structural damage.

Wire rope must be removed from service if what percentage of wires in one rope lay are broken?

Answer: 10%

ASME B30.5 and OSHA criteria require removal from service if 10 randomly distributed broken wires are found in one rope lay, or 5 broken wires in one strand in one rope lay.

Under OSHA's crane standard, what is required when a crane must work within the 'encroachment zone' of a power line?

Answer: An observer must be positioned to monitor clearance

When working within the encroachment zone, OSHA requires an observer to be positioned to monitor the clearance between the crane and power lines.

What is the maximum angle from vertical at which a standard screw pin anchor shackle should be loaded?

Answer: 30 degrees

Shackles should ideally be loaded in-line; angled loading beyond 45° (some manufacturers specify 30°) significantly reduces the working load limit.

Which of the following is a required qualification for a 'signal person' under OSHA's crane standard?

Answer: Must be qualified per OSHA 29 CFR 1926.1419 by a qualified evaluator

Signal persons must be qualified by a third-party qualified evaluator or by an employer-conducted qualification program meeting OSHA requirements.

A synthetic web sling must be removed from service if it has a cut that extends through:

Answer: Any portion of the webbing

Any cut through the webbing of a synthetic web sling requires immediate removal from service — even a partial cut compromises the entire sling.