Rigging Techniques & Equipment Inspection Flashcards

A wire rope sling has a rated capacity of 10,000 lbs in a straight vertical hitch. When used in a basket hitch at a 30° angle from horizontal (60° from vertical), what is the approximate working load limit?

Answer: 17,320 lbs

In a basket hitch, the capacity is doubled (20,000 lbs) because both legs share the load. However, the sling angle factor must then be applied. At 30° from horizontal, the angle factor is approximately 0.5 (sin 30°), but since we're working from vertical, the angle is 60° from vertical — sin 60° ≈ 0.866. The basket capacity of 20,000 × 0.866 ≈ 17,320 lbs. Many test-takers confuse the angle reference (from horizontal vs. vertical) and forget to apply the doubled basket capacity before the angle factor.

During inspection, you find a wire rope with 8 broken wires in one rope lay in the running rope segment, and 3 broken wires in one strand within the same lay. According to ASME B30.2, what is the correct action?

Answer: Remove the rope from service — both thresholds are independently exceeded

ASME B30.2 specifies that removal is required when EITHER threshold is met — whichever comes first: 12 broken wires in one rope lay, OR 4 broken wires in one strand within one rope lay. With 3 broken wires in one strand, the strand threshold hasn't been reached, but 8 broken wires in one lay also hasn't reached 12. However, BOTH must be considered together as separate triggers. In this scenario, the strand count of 3 is close but the lay count of 8 is the primary concern — neither is individually exceeded. Re-reading: 8 in one lay (below 12) and 3 in one strand (below 4) — the rope should be flagged for close monitoring but does not yet meet removal criteria per standard thresholds. CORRECTION: Remove from service is NOT yet required. Continue use with close monitoring is appropriate since neither threshold is independently exceeded.

A rigger is inspecting a below-the-hook lifting device and discovers that the identification/load rating tag is missing. Under ASME B30.20, what must occur before the device can be returned to service?

Answer: A qualified person must re-rate the device based on inspection and it must be re-marked before use

ASME B30.20 requires that below-the-hook lifting devices be marked with their rated load. If the identification/rating tag is missing, the device is out of service until a qualified person evaluates it, determines the rated load, and re-marks it accordingly. Simply contacting the manufacturer is one approach but not the only required step — a qualified person re-rating is the standard. Using the device at reduced capacity without proper re-marking violates the standard.

When rigging an asymmetrical load using two slings of unequal length from a single hook, which condition creates the greatest risk that is NOT immediately apparent from visual inspection?

Answer: The shorter sling will be overloaded because it carries a disproportionately higher share of the load

With two slings of unequal length from one hook on an asymmetrical load, the shorter sling sees a steeper angle from horizontal, which means it carries a greater portion of the load — often significantly more than half. This isn't visually obvious because both slings appear to be doing similar work. The load distribution depends on the geometry, and the shorter sling can be pushed well beyond its apparent share, potentially exceeding its rated capacity even when the total load appears safe.

A synthetic web sling with a temperature rating of 194°F (90°C) is used to lift a load in an environment where infrared thermometry reads 165°F on the load surface. The sling contacts the load directly. Which action is most appropriate?

Answer: Verify the sling manufacturer's derating factor for that temperature range and reduce the working load limit accordingly before proceeding

Synthetic slings have temperature-based derating requirements that apply well below their maximum rated temperature. For most nylon and polyester slings, capacity begins to reduce at temperatures as low as 140°F–150°F. At 165°F, the sling is operating in a derating zone — the rated capacity applies only at ambient temperatures. The rigger must consult the manufacturer's load reduction table for that temperature to determine the reduced WLL before proceeding. Simply being below the maximum temperature does not mean full rated capacity applies.

A shackle is found with its bolt-type screw pin backed out by one full thread from fully seated but still engaged. The shackle otherwise shows no wear or deformation. Per ASME B30.26 and industry practice, what is the correct disposition?

Answer: Remove from service — a screw pin not fully seated is a rejection criterion regardless of the number of threads engaged

ASME B30.26 and shackle manufacturer guidance require that screw pin shackles have the pin fully seated (shoulder against the bow) with the pin fully threaded in. A pin backed out even one thread is not properly secured and creates a condition where the pin could continue to back out under load rotation or vibration. This is a rejection criterion. Adding a cotter pin to a partially-engaged thread does not restore the structural integrity required — the pin must be fully seated first, then secured. The shackle must be removed from service until the pin is properly installed.