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What is a critical lift?

Per BS 7121 / OSHA, a critical lift is one where the capacity utilization is 75% or higher, or any lift over live process plant, or a tandem dual crane lift. Critical lifts require an Appointed Person (AP) sign-off before execution.

How is sling leg tension calculated?

Sling Leg Tension = (Total Gross Load / Number of Legs) × (1 / sin(Sling Angle)). For example, a 20-ton load on 4 legs at 60° gives 20/4 / sin(60°) = 5.77 tons per leg. Always verify the shackle WLL safety factor is ≥ 2:1.

How is outrigger mat size determined?

The maximum outrigger pad load (worst case 50% of gross load on one side, dynamic factor 1.2×) is divided by the soil bearing capacity. Compacted gravel ≈ 200 kN/m², concrete ≈ 500 kN/m², uncompacted soil ≈ 100 kN/m².

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AP Lifting Plan & Capacity Calculator

Per BS 7121 / LOLER / OSHA 1926.451 — Multi-Page PDF Package with 2D Elevation

Project

Load

Crane

Rigging & Site

Project & Location Data

Project Name

Client

Site Location

Document Reference

Lifting Category

Sign-Off Roster (for PDF)

Appointed Person (AP)

Lift Supervisor

Crane Operator

Client HSE Rep

Step 1 of 4

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