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Unit 1 — Workplace Safety and Equipment Management
Section 4 — Hoisting, Lifting, & Rigging

4.4 Load Rigging Factors

Identifying the right rigging configuration requires a systematic assessment of several interdependent factors. Neglecting any one factor can compromise the safety of the lift.

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📋Overview ⚖️Load Characteristics 📌Anchor Points 📊Equipment Capacity 🪢Sling Selection 🏗️Work Environment

4.4.1 The Five Rigging Factors — At a Glance

Before any lift, a competent person must evaluate all five factors below. Each factor influences equipment selection, configuration, and the overall safety of the operation.

Factor Key Assessment Question Action if Unclear
Load Characteristics What is the weight, CoG location, and fragility? Consult equipment submittal sheets or manufacturer documentation
Anchor Points Are the attachment points manufacturer-designated lifting lugs? Do not proceed until confirmed — no improvised attachment points
Equipment Capacity Does every component's WLL exceed the load in that configuration? Recalculate using sling angle derating; upgrade components as needed
Type of Slings What are the surface finish, temperature, and chemical conditions? Select sling type per the sling selection criteria in Lesson 4.3
Work Environment Are exclusion zones established and overhead obstructions clear? Assess utilities, ground bearing, and bystander exposure before rigging

4.4.2 Factors in Detail

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1 — Load Characteristics

Determine the weight, dimensions, shape, and fragility of the load before selecting any rigging component. Never estimate — obtain verified data from equipment submittal sheets or manufacturer documentation.

  • Confirm the total lift weight from documentation — never estimate.
  • Locate the Centre of Gravity (CoG) using manufacturer data or a low trial lift.
  • Identify fragile surfaces, finishes, or housings that could be damaged by sling contact.
  • Determine whether any internal components (compressors, heat exchangers) may shift during the lift and affect balance.
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2 — Anchor Points & Attachment Locations

Use only manufacturer-designated lifting lugs, eyes, or lifting holes where provided. Lifting lugs are designed with specific load angles — do not exceed the rated angle of the lug.

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Never Attach Rigging To: Handles, conduit, refrigerant lines, electrical knockouts, or any structural member not specifically designed and rated for lifting loads. These attachments can fail suddenly and without warning.
  • Confirm that lifting lugs or eyes are present and undamaged.
  • Verify the rated angle of each lifting lug — exceeding it reduces its capacity.
  • If manufacturer lifting points are not provided, a qualified engineer must specify attachment locations.
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3 — Equipment Capacity & Load Charts

Determine the maximum lift weight including rigging weight. Every component in the rigging assembly must have a WLL that exceeds the maximum load acting on that component.

Verify the Entire Chain

  • Crane or hoist
  • Hook and safety latch
  • Shackles and connecting hardware
  • Slings (all legs)
  • Lifting lugs on the load

Apply Sling Angle Derating

  • As sling legs spread further from vertical, each leg carries a greater share of the load.
  • At 60° from vertical: each leg carries ~115% of proportional share.
  • At 45° from vertical: apply a 0.71 angle factor to each leg's WLL.
  • Always use the most restrictive WLL in the assembly.
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The weakest component governs the lift. Upgrading the crane capacity is useless if a shackle or sling leg is undersized. Every link in the rigging chain must be verified.
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4 — Type of Slings

Select sling type based on load weight, surface finish, temperature, chemical environment, and load shape. No single sling type is best for all situations.

Wire Rope Slings

  • Best for heavy, rough loads.
  • Heat-resistant; suitable for outdoor and industrial conditions.
  • Pad contact points to protect finished surfaces.

Synthetic Web Slings

  • Best for light or finish-sensitive loads (painted housings, polished surfaces).
  • Lightweight and flexible — easy to position.
  • Protect from sharp edges with corner protectors.

Chain Slings

  • Best for high-temperature environments or loads with sharp edges.
  • Grade 80 or Grade 100 alloy steel only.
  • Heavier and less flexible than wire or web slings.
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5 — Work Environment

The work environment shapes every aspect of lift planning. A lift that is straightforward in an open yard may be hazardous in a confined mechanical room or near live services.

  • Access restrictions — confirm clear travel paths for equipment and personnel.
  • Overhead obstructions — identify structural members, ductwork, piping, and power lines above the lift zone.
  • Ground conditions — verify bearing capacity; use outrigger pads on soft or uneven surfaces.
  • Proximity to services — identify live electrical, gas lines, and refrigerant piping within the lift radius.
  • Other workers — establish and enforce an exclusion zone around the entire lift area before and during the lift.
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Pre-Lift Meeting Before any significant lift, hold a brief tailgate meeting with all involved workers — rigger, signaller, equipment operator, and ground crew. Confirm roles, signals, abort criteria, and the exclusion zone boundary.
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