Select and Use Rigging and Hoisting Equipment

Choosing and Using Lifting and Rigging Equipment

Introduction to Rigging in Boilermaking

Rigging and lifting are fundamental skills of the boilermaker trade. Before any lifting operation, you must be able to determine the total load, select the appropriate equipment, inspect the accessories, and calculate working angles. This chapter covers all the knowledge required for the Red Seal exam, including applicable Canadian standards, load calculations, and safe procedures.

Canadian lifting regulations are based primarily on the Canada Labour Code (Canada Occupational Health and Safety Regulations) for federal jurisdictions, and on CSA (Canadian Standards Association) standards for equipment and practices. Key standards include CSA Z150 (Safety Code on Mobile Cranes), CSA B167 (Safety of Overhead Cranes and Monorails), and CSA Z248 (Tower Crane Safety Code). Although these standards are voluntary, they are adopted by reference in most provincial and territorial legislation.

Essential Terminology

Calculating the Total Load

Weight of the Load

The first step in any lift is to determine the actual weight of the load. For a boilermaking piece, this involves calculating the volume and multiplying by the density of the material.

Basic formula: Weight (kg) = Volume (m³) × Density (kg/m³)

Common densities:

Example: A carbon steel plate measuring 2 m × 1 m × 25 mm (0.025 m).

Volume = 2 × 1 × 0.025 = 0.05 m³

Weight = 0.05 × 7,850 = 392.5 kg

Dynamic Load Factors

During lifting, dynamic forces are added to the static weight. The impact factor accounts for acceleration, braking, and jerks. For exam calculations, a factor of 1.25 is generally used for normal lifts and 1.5 for lifts with shock loading risks.

Design load = Static weight × Impact factor

Calculating the Centre of Gravity

The centre of gravity (CG) is the point where the entire mass of the load is considered to be concentrated. For a stable lift, the hook must be directly above the CG. If the CG is offset, the load will tilt.

Calculating the CG for a compound load:

CG = (Σ (Weightᵢ × Distanceᵢ)) / Σ Weightᵢ

Example: A 3 m beam with a mass of 600 kg uniformly distributed and a 200 kg block attached 1 m from the left end.

CG = (600 × 1.5 + 200 × 1.0) / (600 + 200) = (900 + 200) / 800 = 1100 / 800 = 1.375 m from the left end.

Slings and Rigging Accessories

Wire Ropes

Wire ropes are made of strands wound around a core. The construction is designated by two numbers: the number of strands and the number of wires per strand. For example, a 6 × 19 rope has 6 strands of 19 wires each.

Types of cores:

Safety factor for wire ropes: 5 for general lifting, 6 for lifting personnel.

Calculating breaking load: Breaking load (kg) = Diameter² (mm) × Construction coefficient

For a 6 × 19 rope with an independent wire rope core, the coefficient is approximately 42.5 (in kg/mm²).

Example: 16 mm diameter rope, 6 × 19 IWRC construction.

Breaking load = 16² × 42.5 = 256 × 42.5 = 10,880 kg

SWL = 10,880 / 5 = 2,176 kg

Wire Rope Slings

Wire rope slings are manufactured with splices or shackles. Their capacity depends on the diameter, configuration, and angle of use.

Sling configurations:

Chain Slings

Chain slings are used for abrasive loads, high-temperature applications, or loads with sharp edges. They conform to CSA G4 (Steel Chains). Grade 80 (T) chain is the most common in boilermaking.

Grade 80 chain capacities (SWL in kg):

Synthetic Web Slings

Synthetic web slings are lightweight, flexible, and will not scratch surfaces. They conform to CSA Z259.15 (Textile Lifting Slings). Their capacity is reduced in the presence of sharp edges, chemicals, or extreme temperatures.

Maximum operating temperatures:

Capacity reduction with sharp edges:

Calculating Angles and Tensions

Included Angle and Horizontal Angle

The angle between the legs of a sling is critical. As the angle increases, the tension in each leg increases.

Tension formula per leg:

T = (Weight × Safety factor) / (Number of legs × sin(θ))

Where θ is the horizontal angle between the leg and the horizontal.

Reduction factors based on included angle:

Rule of thumb: The included angle should never exceed 90° for two-leg slings. Beyond 120°, the tension becomes excessive and the lift is dangerous.

Example: A 2,000 kg load is lifted with a two-leg sling forming a 60° included angle.

Tension per leg = 2,000 / (2 × sin(60°)) = 2,000 / (2 × 0.866) = 2,000 / 1.732 = 1,155 kg

The capacity of each leg must be at least 1,155 kg.

Effect of Angle on Sling Capacity

The capacity of a sling is always given for vertical use. For angled use, multiply by the appropriate factor.

Effective capacity = Vertical capacity × Angle factor

Example: A sling with a vertical capacity of 2,000 kg is used at a horizontal angle of 45°.

Effective capacity = 2,000 × 0.707 = 1,414 kg

Shackles, Hooks, and Lifting Lugs

Shackles

Shackles are classified by type (anchor or chain) and capacity. The pin may be screw type or cotter type. The applicable standard is CSA B354 for lifting shackles.

Types of shackles:

Usage rule: The pin must always be in place and fully threaded. Never replace the pin with an ordinary bolt.

Hooks

Lifting hooks must be equipped with a safety latch to prevent the sling from becoming detached. Hooks conform to CSA Z150 for mobile cranes.

Hook rejection criteria:

Lifting Lugs and Rings

Lifting lugs are welded onto boilermaking components. Their design must account for the direction of the load. A lug designed for a vertical load can fail under a lateral load.

Inspection and Rejection Criteria

Wire Rope Inspection

Wire ropes must be inspected before each use and periodically by a competent person. Rejection criteria include:

Number of broken wires over a length of 6 diameters:

Other rejection criteria:

Chain Sling Inspection

Chains must be inspected for:

Synthetic Web Sling Inspection

Web slings must be inspected for:

Safe Lifting Procedures

Lift Planning

Before any lift, you must:

Standardized Hand Signals

Hand signals for crane operations are standardized according to CSA Z150. Essential signals include:

Pre-Lift Verification

Test lift procedure:

Fundamental Safety Rules

Applicable Canadian Standards

CSA Z150 — Safety Code on Mobile Cranes

This standard covers the design, inspection, maintenance, and operation of mobile cranes. Key requirements include:

CSA B167 — Safety of Overhead Cranes and Monorails

This standard applies to overhead cranes used in boilermaking shops. It covers:

CSA Z248 — Tower Crane Safety Code

Applicable to tower cranes used on large construction sites. Requirements include:

Canada Occupational Health and Safety Regulations

The Canada Occupational Health and Safety Regulations (SOR/86-304) applies to employers under federal jurisdiction. Relevant sections include:

Advanced Rigging Calculations

Calculating the Capacity of a Multi-Leg Sling

For a four-leg sling, the capacity is not simply four times the capacity of one leg. In practice, it is considered that only three legs support the load due to irregularities in load distribution.

Practical capacity of a 4-leg sling = Capacity of one leg × 3 × Angle factor

Calculating the Overturning Moment

For a mobile crane, the overturning moment is the product of the load and the horizontal distance between the centre of rotation and the line of action of the load.

Overturning moment = Load × Radius

The stabilizing moment is the product of the crane's weight and the distance between the crane's centre of gravity and the tipping point. Stability is ensured when the stabilizing moment is greater than the overturning moment.

Calculating Wire Rope Sag

The sag of a rope under tension is important for determining the actual hook height.

Approximate formula: Sag (m) = (Weight of rope per metre × Span²) / (8 × Tension)

Common Pitfalls to Avoid

Summary

Exam Tips

Mastery of rigging is essential for safety and success on the Red Seal exam. Questions on this topic represent a significant portion of the exam, and calculations involving angles and capacities are frequently tested. Practice with varied exercises until the formulas and factors are fully integrated.