Material Handling, Rigging, and Hoisting

Material Handling, Rigging, and Lifting

Chapter Introduction

Material handling, rigging, and lifting are fundamental skills for the Construction Craft Worker (CCW). On Canadian job sites, a significant proportion of serious and fatal accidents involve lifting operations: falling objects, sling failure, load tipping, or contact with overhead power lines. This chapter covers the mechanical principles, equipment, safe procedures, load calculations, and federal regulatory requirements you must master for the Red Seal exam.

This chapter is structured according to the tasks and sub-tasks of the National Occupational Analysis for the Construction Craft Worker trade, competency block C: "Perform material handling, rigging, and lifting."

Fundamental Principles of Lifting

Gravity and the Centre of Gravity

Every object has a centre of gravity (CG) — the point where the total mass of the object is considered to be concentrated. For a uniform, symmetrical object, the CG is at the geometric centre. For an irregular load, the CG shifts toward the heavier part.

Golden rule: The lifting hook must be directly above the load's centre of gravity. If it is not, the load will tip or swing as soon as it leaves the ground.

Calculating the CG for a compound load: Divide the load into simple shapes. For each shape, determine its weight (W) and the distance of its CG from a reference point (d). The overall CG is:

CG = (W₁ × d₁ + W₂ × d₂ + …) ÷ (W₁ + W₂ + …)

Example: A 6 m beam weighing 300 kg supports a 150 kg motor fixed 2 m from the left end. The CG of the beam is at 3 m. The combined CG is:

CG = (300 × 3 + 150 × 2) ÷ (300 + 150) = (900 + 300) ÷ 450 = 1200 ÷ 450 = 2.67 m from the left end.

Weight and Mass

Mass: quantity of matter (kg).

Weight: the force exerted by gravity on that mass (N or kgf).

On Earth, 1 kg of mass weighs approximately 9.81 N (≈ 10 N for practical calculations). For the exam, use the conversion: 1 kg ≈ 2.2 lb and 1 metric tonne (t) = 1000 kg.

Useful conversions:

Unit	Equivalent
1 kg	2.2046 lb
1 t (metric tonne)	2204.6 lb
1 lb	0.4536 kg
1 kN	≈ 100 kgf
1 m³ of water	1000 kg (1 t)

Lifting Equipment and Capacities

Slings

Slings are the connecting elements between the crane hook and the load. The choice of sling depends on the weight, shape, temperature, and environmental conditions.

Wire Rope Slings

Construction: strands twisted around a core (fibre or steel).

Advantages: high strength, resistance to abrasion and heat.

Disadvantages: stiff, can damage fragile loads, risk of deformation.

Mode factors (sling angle): The capacity of a sling decreases as the angle between the legs increases. The mode factor is a multiplier applied to the sling's rated capacity in a vertical configuration.

Angle at hook (from vertical)	Mode factor
90° (vertical)	1.00
60°	0.87
45°	0.71
30°	0.50
0° (horizontal)	0.00 (prohibited)

Rule: The angle between two legs of the same sling must never be less than 30° (angle at the hook). In practice, a 60° angle at the hook is considered the minimum acceptable for stability.

Calculating tension in each leg:

T = (Load weight ÷ Number of legs) × (1 ÷ sin(angle at hook))

Example: Load of 2000 kg, 2 legs, 60° angle at the hook.

T = (2000 ÷ 2) × (1 ÷ sin 60°) = 1000 × (1 ÷ 0.866) = 1000 × 1.155 = 1155 kg per leg.

Chain Slings

Grade 80 (alloy) and Grade 100 are the most common.

Advantages: flexibility, abrasion resistance, tolerance to high temperatures (up to 200 °C for grade 80).

Disadvantages: heavy, sensitive to shock loads and corrosion.

Indicative rated capacity (grade 80 chain):

Link diameter	Vertical capacity (kg)
8 mm	800
10 mm	1250
13 mm	2000
16 mm	3200
20 mm	5000

Synthetic Web Slings

Polyester, nylon, polypropylene.

Advantages: lightweight, flexible, will not scratch surfaces.

Disadvantages: sensitive to cuts, heat (> 100 °C), UV rays, and chemicals.

Sling identification code: The rated capacity is indicated on a sewn-in label. An illegible or missing label renders the sling out of service.

Rigging Hardware

Hooks: must be equipped with a functioning safety latch. An open or deformed hook is out of service.

Shackles: check the pin diameter and wear. The load must be applied along the axis of the shackle.

Lifting eyes: used for threaded or bolted loads.

Grapple, spreader bar: specialized equipment for long or bulky loads.

Sling Inspection

Before each use:

Wire rope: look for broken wires, kinks, corrosion, deformations (birdcaging, basketing), and wear.

Chain: elongated links, cracks, deformations, impact marks.

Web sling: cuts, tears, open seams, missing label.

Out-of-service criteria (wire rope):

6 broken wires over one rope lay length (or 3 broken wires in one strand).

Diameter reduction of more than 7% from the nominal diameter.

Visible corrosion or pitting.

Permanent deformation (bending, crushing).

Load Calculations and Safety Factors

Rated Load and Working Load

Working Load Limit (WLL): the maximum load that equipment can support under normal operating conditions.

Breaking load: the load that causes equipment failure.

Safety factor: the ratio between the breaking load and the rated load.

Typical safety factors:

Equipment	Safety factor
Wire rope	5:1
Grade 80 chain	4:1
Synthetic web sling	7:1
Hook	4:1
Shackle	5:1

Total Load to be Lifted

The total load includes:

71.The net weight of the load.

72.The weight of the rigging hardware (slings, shackles, spreader bars).

73.Any dynamic forces (acceleration, wind, suction).

Formula: Total load = Net weight + Weight of hardware + Dynamic factor (generally 10% of the net weight for normal operations).

Crane Capacity and Radius

The capacity of a mobile crane decreases as the radius (horizontal distance between the axis of rotation and the centre of the load) increases. This relationship is illustrated on the crane's load chart.

Rules for using the load chart:

Always use the actual crane configuration (boom length, outriggers deployed or not, counterweights).

The rated capacity is for firm, level ground.

Outriggers must be deployed and cribbed on load-spreading pads.

Wind and ground conditions can reduce capacity.

Trap to avoid: Never linearly interpolate between two values on the load chart without verifying the method prescribed by the manufacturer.

Rigging Procedures

Choosing the Rigging Configuration

Configuration	Description	Mode factor
Single sling	One vertical leg	1.00
Choker hitch	Sling passed around the load, both ends at the hook	2.00 (but the load is supported by two legs)
Basket hitch	Sling passed under the load, both ends at the hook	2.00
Basket hitch with angle	Basket hitch with inclined legs	Depends on the angle
Two slings	Two vertical legs	2.00
Two slings with angle	Two inclined legs	Depends on the angle (see table above)

Calculation example for a basket hitch: A 10 mm wire rope sling has a vertical capacity of 1000 kg. In a basket hitch (factor 2.0), the capacity becomes 2000 kg. But if the legs are at 60° at the hook, the mode factor is 0.87 × 2.0 = 1.74. The capacity is therefore 1740 kg.

Safe Rigging Procedure

89.Plan: identify the weight, CG, travel path, and obstacles.

90.Inspect: slings, hooks, shackles, anchor points.

91.Position: place the sling under the load, centred on the CG.

92.Attach: use appropriate hitches or hardware. Never tie a knot in a wire rope sling.

93.Verify: ensure the sling is not twisted, angles are acceptable, and sharp edges are protected (edge protectors).

94.Tension: lift slowly to take up the load, check balance, then continue.

95.Guide: use tag lines to control rotation. Never guide the load with your hands.

96.Set down: lower slowly onto a stable surface, using cribbing if necessary.

Crane Hand Signals

The signaller (rigger) must know the standardized hand signals from the Canada Labour Code and ANSI/ASME B30.5. Signals must be given by one designated person only.

Basic signals:

Signal	Meaning
Arm extended, thumb up	Hoist
Arm extended, thumb down	Lower
Arm extended horizontally, open hand, palm down, lateral movement	Swing boom
Arm bent, forearm vertical, fist closed, circular motion	Rotate
Both arms crossed in front of chest	Emergency stop

Canadian Regulations and Standards

Canada Labour Code (CLC) — Part II

The Canada Labour Code, Part II (Canada Occupational Health and Safety Regulations) applies to work sites under federal jurisdiction. Relevant sections include:

Section 14.1: Lifting and transporting — the employer must ensure that lifting equipment is inspected and maintained.

Section 14.2: Slings must be inspected before each use.

Section 14.3: Loads must not be suspended over workers.

Section 14.4: Workers must not stand under a suspended load.

CSA B167 — Overhead Cranes and Hoists

The CSA B167 standard (Safety standard for overhead cranes, gantry cranes, monorails, hoists, and jib cranes) specifies inspection, testing, and maintenance requirements. It defines inspections:

Frequent: before each work shift (visual).

Periodic: monthly or quarterly (more detailed).

Initial: before first commissioning.

CSA Z150 — Mobile Cranes

The CSA Z150 standard (Safety code on mobile cranes) covers the design, inspection, operation, and maintenance of mobile cranes. Key points:

The crane operator must be qualified and hold a certificate of competency.

The load chart must be available in the cab.

Outriggers must be used according to specifications.

Loads must never exceed the rated capacity.

CSA Z248 — Tower Cranes

The CSA Z248 standard applies to tower cranes. It requires periodic inspections and load testing.

Crane Regulations — Canadian Electrical Code, Chapter V

The Canadian Electrical Code, Chapter V (C22.1-21) addresses minimum distances between lifting equipment and overhead power lines.

Minimum clearance distances (line voltage):

Line voltage (kV)	Minimum distance (m)
0 to 750 V	3.0 m
750 V to 75 kV	4.5 m
75 kV to 250 kV	6.0 m
250 kV to 550 kV	8.0 m

Golden rule: If the minimum distance cannot be maintained, the electrical utility operator must be contacted to de-energize or protect the line.

Lifting Devices Regulations (Canada)

The Lifting Devices Regulations (SOR/88-69) applies to lifting devices used in federal undertakings. It requires:

Annual inspections by a competent person.

Load testing after any major repair.

An up-to-date inspection log.

Manual Material Handling Techniques

Safe Lifting Principles

135.Assess the load: weight, shape, size, stability.

136.Position your feet: shoulder-width apart, one foot slightly forward.

137.Bend your knees: keep your back straight, chin tucked in.

138.Grip firmly: palms facing up if possible.

139.Lift with your legs: keep the load close to your body.

140.Do not twist your torso: pivot with your feet.

Recommended lifting limits (general guideline):

Situation	Limit (kg)
Floor to knuckle height	23 kg (women), 34 kg (men)
Floor to shoulder height	15 kg (women), 23 kg (men)
Floor to above shoulder height	9 kg (women), 14 kg (men)

These values are indicative; the Canada Occupational Health and Safety Regulations require a risk assessment for each manual handling task.

Mechanical Handling Aids

Pallet jack: typical capacity of 2000 to 3000 kg.

Forklift: capacity of 1500 to 5000 kg depending on the model.

Spreader bar: for long loads (pipes, beams).

Vacuum lifter: for glass panes, panels.

Plate clamp: for sheet metal, concrete blocks.

Traps to Avoid

152.Confusing rated load and breaking load: the rated load is the maximum working load, never the breaking load.

153.Forgetting the weight of rigging hardware: the weight of slings, shackles, and spreader bars must be included in the total load.

154.Neglecting the sling angle: the narrower the angle, the greater the tension in each leg. A 30° angle at the hook doubles the tension compared to a 90° angle.

155.Using a damaged sling: any deformation, cut, or missing label renders the sling out of service.

156.Standing under a suspended load: this is prohibited by the Canada Labour Code, even for a "brief" moment.

157.Ignoring the crane's load chart: capacity changes with radius, configuration, and ground conditions.

158.Tying a knot in a wire rope sling: this reduces capacity by 50% or more and is prohibited.

159.Failing to protect sharp edges: a sharp edge can cut a synthetic web sling or damage wire rope.

160.Using non-standardized signals: all signals must conform to the standard and be understood by the crane operator.

161.Underestimating the effect of wind: a light, wide load can be destabilized by wind.

Summary

The centre of gravity must be under the lifting hook to prevent tipping.

Mode factors reduce sling capacity based on the rigging angle. The minimum angle at the hook is 30°.

Tension in each leg is calculated using the formula T = (Weight ÷ Number of legs) × (1 ÷ sin(angle)).

Slings (wire rope, chain, synthetic web) must be inspected before each use and taken out of service if defective.

Total load includes net weight, rigging hardware, and dynamic factors.

The crane's load chart must be consulted for every lift.

Minimum distances from power lines are defined by the Canadian Electrical Code, Chapter V.

The CSA B167, CSA Z150, and CSA Z248 standards govern lifting equipment.

Manual handling follows biomechanical principles: back straight, knees bent, load close to the body.

The Canada Labour Code, Part II prohibits suspending loads over workers and requires regular inspections.

Self-Assessment Questions

176.A 1500 kg load is rigged with two legs at a 45° angle at the hook. What is the tension in each leg?

Answer: T = (1500 ÷ 2) × (1 ÷ sin 45°) = 750 × 1.414 = 1060.5 kg.

178.A 12 mm wire rope sling has a vertical capacity of 1200 kg. What is its capacity in a basket hitch with a 60° angle at the hook?

Answer: Mode factor = 2.0 × 0.87 = 1.74. Capacity = 1200 × 1.74 = 2088 kg.

180.What is the minimum distance to maintain between a crane and a 120 kV power line?

Answer: 6.0 m (according to the Canadian Electrical Code, Chapter V).

182.What are the three out-of-service criteria for wire rope?

Answer: 6 broken wires over one rope lay length, diameter reduction of 7%, permanent deformation.

184.Which CSA standard governs mobile cranes?

Answer: CSA Z150.

Normative References

Canada Labour Code, Part II — Canada Occupational Health and Safety Regulations.

Lifting Devices Regulations (SOR/88-69).

CSA B167 — Safety standard for overhead cranes, gantry cranes, monorails, hoists, and jib cranes.

CSA Z150 — Safety code on mobile cranes.

CSA Z248 — Safety code for tower cranes.

Canadian Electrical Code, Chapter V (C22.1-21).

ANSI/ASME B30.5 — Mobile and Locomotive Cranes (reference for hand signals).

This chapter prepares you for the Red Seal exam questions on material handling, rigging, and lifting. Master the calculations, mode factors, and standards — these elements appear consistently on the exam.