Safety, Rigging, and Hoisting Practices

Safety, Rigging, and Lifting Practices

Chapter Introduction

This chapter covers all the knowledge required for the Red Seal exam in metal fabrication (fitter) regarding safety, rigging, and lifting practices. You must master load calculation principles, sling selection, equipment inspection, and safe procedures. Exam questions often focus on practical situations where a calculation error or poor equipment choice can lead to a serious accident. Canadian regulations require that every worker involved in lifting operations be familiar with CSA standards and the regulations of the Canada Labour Code.

Legal Responsibilities and Applicable Standards

Canadian Regulatory Framework

In Canada, lifting operations are governed by several national standards. The Canada Labour Code (Part II) establishes the general obligations of employers and employees. For lifting equipment, the CSA B167 standard (Safety of overhead cranes and monorails) is the primary reference. Slings and lifting accessories are covered by the CSA Z150 standard (Safety of mobile cranes) and CSA Z248 standard (Safety of tower cranes). The CSA B354 standard applies to elevating work platforms.

The Canada Occupational Health and Safety Regulations (federal COHSR) specify inspection and maintenance requirements. Sections 14.2 to 14.9 deal specifically with lifting devices. You must know the inspection frequencies: daily inspection before use, periodic monthly inspection, and complete annual inspection by a competent person.

Obligations of the Metal Fabricator-Fitter

As a metal fabricator-fitter, you are responsible for:

Fundamental Principles of Lifting

Centre of Gravity and Stability

The centre of gravity (CG) is the point where the entire mass of an object is considered to be concentrated. For a stable lift, the hook must be positioned directly above the CG. If the hook is offset, the object will tip. The rule of thumb: the vertical projection of the CG must fall within the base of support formed by the attachment points.

To locate the CG of a compound part, divide the part into simple geometric shapes, calculate the CG of each shape, then find the weighted average. The static moment with respect to a reference axis equals the sum of the masses multiplied by their distances from that axis.

Sling Angle and Tension Factor

The sling angle is the angle formed between the sling and the horizontal. The smaller this angle, the higher the tension in each leg. The formula for calculating tension per leg is:

T = (P / n) × (1 / sin θ)

Where:

Table of tension factors for 2-leg slings

At 30°, each leg already supports 100% of the total load (for 2 legs). At 5°, tension reaches nearly 6 times the load weight. The minimum recommended angle is 30°, and the optimal angle is 60° or greater.

Rated Capacity and Safety Factor

The rated capacity (or safe working load) is the maximum load that equipment can support under normal operating conditions. It is calculated by dividing the breaking strength by the safety factor. For steel wire rope slings, the safety factor is 5:1. For synthetic slings, it is also 5:1 according to CSA standards. Lifting chains have a safety factor of 4:1.

The rated capacity indicated on the tag assumes a sling angle of 90° (vertical). For any other angle, the appropriate reduction factor must be applied. Never confuse breaking strength with rated capacity — the exam frequently tests this distinction.

Types of Slings and Their Characteristics

Chain Slings

Chain slings are made of heat-treated alloy steel. They offer excellent resistance to abrasion, heat, and cutting. They are ideal for loads with sharp edges and high temperatures. The CSA G4 standard governs their manufacture and use.

Main characteristics:

Table of typical rated capacities (Grade 80 chain)

Steel Wire Rope Slings

Steel wire rope slings consist of strands twisted around a core. They offer high strength and good flexibility. Common types are 6×19 (6 strands of 19 wires) and 6×37. The core can be fibre (FC), steel (IWRC), or compacted steel.

Rejection criteria according to CSA standards:

The rope lay length is the longitudinal distance required for one strand to make a complete revolution around the core. To calculate it, measure the distance between two successive crowns of the same strand.

Synthetic Slings (Webbing and Rope)

Synthetic slings are made of polyester, nylon, or polypropylene. They are lightweight, flexible, and do not damage finished surfaces. Their colour indicates the rated capacity according to the Web Sling and Tie Down Association (WSTDA) code.

Table of colour codes for synthetic webbing slings

Synthetic slings are sensitive to cuts, abrasion, and chemicals. They must not be used at temperatures exceeding 90 °C (polyester) or 120 °C (nylon). Stitching must be inspected — any broken or frayed stitching renders the sling unusable.

Lifting Accessories

Hooks and Shackles

Hooks must be equipped with a locking device (latches) to prevent accidental detachment. A hook must be rejected if:

Shackles are classified by type: screw pin, round pin, and bolt type. The rated capacity is stamped on the body. The load must be applied along the axis of the shackle. Shackles must never be loaded laterally. Replacing the pin with an ordinary bolt is prohibited — only the original pin may be used.

Lifting Lugs, Eye Bolts, and Spreader Bars

Lifting lugs are welded onto parts to be lifted. Their design must account for the direction of the load. A lug designed for a vertical lift must not be loaded laterally. Spreader bars are used to maintain slings at the desired angle and prevent compression of the load.

Eye bolts are classified into two categories:

Load and Capacity Calculations

Calculating the Weight of Metal Parts

To calculate the weight of a steel part, use the formula:

Weight (kg) = Volume (m³) × Density (kg/m³)

The density of steel is 7,850 kg/m³. For simple shapes:

Example: A plate measuring 2 m × 1 m × 0.025 m weighs: 2 × 1 × 0.025 × 7,850 = 392.5 kg

Calculating the Effective Load with Accessories

The effective load includes the weight of the part plus the weight of the slings and accessories. If you use a spreader bar weighing 50 kg and slings weighing 20 kg to lift a 1,000 kg part, the effective load is 1,070 kg. This value must be compared to the rated capacity of the equipment.

Capacity Reduction Due to Angle

For a 2-leg sling at a 45° angle, the effective capacity is reduced. If the total vertical capacity is 4,000 kg, the capacity at 45° is:

4,000 × sin(45°) = 4,000 × 0.707 = 2,828 kg

This maximum load must be compared to the actual weight of the load. The exam will often provide you with a table of factors — make sure you know how to use it correctly.

Safe Lifting Procedures

Lift Planning

Before any lift, you must:

Standardized Hand Signals

Hand signals are standardized according to CSA standards. The metal fabricator-fitter must know the basic signals:

Step-by-Step Lifting Procedure

Essential Safety Rules

Inspection and Maintenance

Inspection Frequencies

Daily inspection (before each use):

Periodic inspection (monthly or based on usage):

Annual inspection:

Rejection Criteria

A sling must be removed from service if:

Marking and Identification

Each sling must bear a tag indicating:

The tag must be legible and securely attached. A sling without a tag is considered out of service.

Storage and Handling of Equipment

Storage Conditions

Slings must be stored in a dry place, protected from direct sunlight and chemicals. Synthetic slings should be hung or laid flat, never tightly folded. Chains should be lightly oiled to prevent corrosion. Wire ropes should be coiled in regular loops without twisting.

Safe Handling

Special Situations

Lifting Unbalanced Loads

For a load whose centre of gravity is not at the geometric centre, slings must be positioned so that the hook is above the CG. The tension in each leg will be different. Calculating individual tensions requires applying static equilibrium equations:

ΣFy = 0 (sum of vertical forces)

ΣM = 0 (sum of moments)

Example: A beam weighing 2,000 kg and 6 m long with a CG at 2 m from end A. Two vertical slings at the ends. The reactions are:

R_A = (2,000 × 4) / 6 = 1,333 kg

R_B = (2,000 × 2) / 6 = 667 kg

Lifting Long Loads

For long loads (beams, pipes), use a spreader bar or lifting beam to keep the slings vertical. This prevents lateral compression and slipping. The minimum length of the spreader bar depends on the length of the load and the desired sling angle.

Lifting in Cold Environments

At low temperatures, steel becomes more brittle. Grade 80 chain slings retain their capacity down to −40 °C. Synthetic slings become stiff and may crack. Steel wire ropes can lose up to 10% of their capacity at −40 °C. Check manufacturer recommendations for extreme cold conditions.

Common Pitfalls to Avoid

Summary

Mastering these concepts will not only help you pass the exam, but also ensure your safety and that of your colleagues on the job site. Lifting operations are among the most dangerous in metal fabrication — rigour and knowledge of the standards are your best protection.