Lift Planning and Critical Lift Procedures Flashcards

During a critical lift pre-plan, the rigging engineer determines that the center of gravity (CG) of an asymmetric load is offset 18 inches from the geometric center. The lift uses a single four-leg bridle sling with all legs the same length. What is the PRIMARY consequence of this CG offset if no adjustment is made?

Answer: The load will tilt, causing unequal leg tensions that may exceed the rated capacity of the higher-tension legs

When the CG is offset from the geometric center of a symmetric bridle, the legs on the CG side carry disproportionately more load. Those higher-tension legs are the ones at risk of exceeding rated capacity. The legs with less tension are not the failure risk. ASME B30.5 does not categorically prohibit asymmetric loads on bridle slings, and LMI false-trips are unrelated to sling geometry.

A critical lift plan calls for two cranes to tandem-lift a 200-ton vessel. During the lift, one crane's load unexpectedly transfers 15% more load to the second crane due to a ground settlement under Crane 1. Under ASME B30.5 critical lift protocols, which condition BEST describes the team's required response?

Answer: Immediately set the load down if possible; if not, hold position and reassess — the deviation from the lift plan constitutes a changed condition requiring engineer re-evaluation

ASME B30.5 and best-practice critical lift protocols require that any condition deviating from the approved lift plan — including unplanned load redistribution — constitutes a changed condition. The lift must be stopped (or held safely) and the qualified lift director/engineer must re-evaluate before proceeding. A 10% buffer is not a codified 'continue' threshold for tandem lifts, and mechanically compensating (changing boom angle or engine RPM) without re-evaluation violates the plan.

A lift plan specifies a maximum allowable ground bearing pressure of 4,500 psf under the crane mats. The outrigger float measures 36 inches × 36 inches. After the lift begins, the qualified rigger notices one mat has sunk 2 inches on one side, indicating differential settlement. The current load on that outrigger is calculated at 180,000 lbs. What is the FIRST action the lift director should take?

Answer: Stop all crane movement, hold the load, and investigate the ground condition before any further action

The immediate action for any anomalous condition (differential settlement, unexpected sounds, equipment behavior deviating from the plan) is to stop all crane movement and hold — not to calculate or attempt corrections while the load is live. While the bearing pressure calculation in option A is arithmetically correct and alarming, the first action is stopping movement and securing the situation, then assessing. Retracting outriggers under load and adding cribbing under a live suspended load are both unsafe corrective actions.

A lift plan is being developed for a pick-and-carry operation on a 15% side slope using a rough-terrain crane rated at 85 tons. The manufacturer's load chart has a footnote stating: 'Ratings are valid on firm, level ground with outriggers fully extended. Picks and carries on rubber require derating per Appendix A.' Appendix A specifies a 75% derate for carries exceeding 5% grade. What is the EFFECTIVE rated capacity for this carry?

Answer: 63.75 tons, because 85 tons × 75% = 63.75 tons

The manufacturer's load chart and Appendix A govern: a 75% derate applied to the 85-ton rated capacity yields 63.75 tons effective capacity for this carry. ASME B30.5 does not categorically prohibit carries on grades above 10% — manufacturer limitations control. The derate is explicitly for picks and carries on rubber, not just outrigger configurations. There is no universal 50% rubber carry derate in ASME B30.5; manufacturer-specific charts govern.

While reviewing a critical lift plan for a reactor vessel, the lift director notices the plan specifies using a below-the-hook lifting device with a Design Factor of 3:1. ASME B30.20 requires a minimum Design Factor of 3:1 for most below-the-hook devices, but specifies a higher minimum for certain device categories. For which category does ASME B30.20 require a Design Factor greater than 3:1?

Answer: Below-the-hook lifting devices used in personnel hoisting, which require a minimum Design Factor of 10:1 under ASME B30.23

ASME B30.23 (Personnel Lifting Systems) mandates a minimum Design Factor of 10:1 for equipment used to hoist personnel — significantly higher than the 3:1 standard for cargo lifting. While B30.20 governs below-the-hook devices for load lifting, B30.23 imposes the stricter 10:1 requirement when those devices are used in personnel hoisting applications. Vacuum device structural factors, plate clamp factors, and spreader beam length-based factors do not trigger a category-wide Design Factor increase beyond 3:1 in B30.20.

A critical lift plan engineer is calculating the dynamic load factor for a marine vessel pick using a floating crane in a tidal environment. The lift specification sheet states a static load of 320 tons, significant wave height (Hs) of 1.2 meters, and requires applying a dynamic amplification factor (DAF) per the project's offshore lift specification, which mandates DAF = 1.10 for Hs ≤ 1.5m. The crane's derating for below-the-hook rigging is 5%. What is the MINIMUM required crane rated capacity at the applicable radius?

Answer: 369.28 tons — calculated as (320 × 1.10) ÷ 0.95

The dynamic load is first calculated: 320 tons × 1.10 DAF = 352 tons. The rigging derate reduces the crane's effective capacity — it does not reduce the load. To ensure the crane's effective capacity (after the 5% rigging derate) covers the dynamic load, you need: Required Rated Capacity × 0.95 ≥ 352 tons → Required Rated Capacity ≥ 352 ÷ 0.95 = 369.28 tons. Applying the derate to the load (option C) is a conceptual error — derates reduce available capacity, not the load itself. The DAF and derate do not cancel.