Crane Rigging: Hardware Solutions in Tower Crane

What is Crane Rigging？

Crane rigging refers to the process of preparing and securing loads before lifting them with a crane. This includes selecting the right equipment, attaching it to the load correctly, and ensuring everything is balanced and stable before the lift begins.

Types of Cranes Used in Rigging

The primary purpose of rigging is to safely transport heavy equipment and materials to places where workers need them.

Several crane types are commonly used in rigging operations:

Mobile Cranes – These versatile machines have wheels or tracks that allow them to move around job sites.
Tower Cranes – These tall structures are usually work in construction sites. They’re fixed in place but offer excellent height and reach for building construction.
Overhead Cranes – Found in factories and warehouses, these cranes move along tracks on the ceiling.
Boom Trucks – These are essentially trucks with small cranes attached, perfect for lighter loads and jobs requiring mobility.

Common Rigging Equipment

Here’s equipments you’ll regularly use:

Slings – Made from wire rope, chain, or synthetic materials, slings wrap around loads to create lifting points:

Wire rope slings: Strong and resist abrasion
Chain slings: Durable for rough or hot loads
Synthetic slings: Lighter and won’t damage delicate loads

Shackles – These U-shaped metal devices with removable pins connect slings to hooks and other rigging hardware.

Hooks – The connection point between the crane and rigging, hooks come with safety latches to prevent loads from slipping off.

Spreader Beams – When lifting long objects, these horizontal bars distribute weight evenly and maintain stability.

Crane Rigging Safety Standards

OSHA Regulations for Crane Rigging

The Occupational Safety and Health Administration has specific requirements for crane rigging operations. Under standard 1926.251, all rigging equipment must be inspected before each shift and as needed during use to ensure safety.

OSHA prohibits shock loading, which can damage equipment and cause accidents. You must keep all workers clear of suspended loads and never place hands or fingers between a sling and its load while tightening.

For steel erection activities, OSHA standard 1926.753 requires that cranes be visually inspected by a competent person before each shift.

Load Capacity Guidelines

When rigging a crane, you must never exceed the rated load capacity of your equipment. Your rigging system has weight limits which need ti be followed strictly.

Important load capacity considerations:

Check the manufacturer’s specifications for all rigging equipment
Account for the weight of both the load and rigging gear
Consider environmental factors like wind that may affect stability
Adjust for load angles, as angled rigging reduces capacity

Never pull a sling from under a load when the load is resting on the sling. This practice can damage equipment and create unsafe conditions.

Crane Rigging Techniques

Lifting Methods

When planning a lift, you need to choose the best method based on the load’s weight, shape, and center of gravity. The most common lifting methods include straight lifts, basket hitches, and choker hitches.

For straight lifts, you attach the sling directly to the load. This works well for items with built-in lifting points.

Basket hitches wrap around the load, providing more stability and distributing weight evenly. You should use this method for awkwardly shaped objects.

Choker hitches tighten around the load when tension is applied. They’re useful when you need to grip the load securely.

Rigging Calculations

Calculating the load weight and rigging capacity is essential for safe crane operations. You must know your load’s exact weight before selecting rigging equipment.

Use this simple formula to determine if your rigging is adequate:

Working Load Limit (WLL) × number of legs × angle factor = total capacity

The angle factor decreases as sling angles become more horizontal:

90° angle = 1.0 factor
60° angle = 0.87 factor
45° angle = 0.71 factor
30° angle = 0.50 factor

The safety factor typically is 5:1 for most rigging operations.

Rigging in Tower Crane

Proper rigging secures heavy loads, distributes weight evenly, and prevents accidents caused by equipment failure, load shifts, or structural imbalances.

Core Rigging Components

Wire ropes are composed of multiple steel strands like 6×19 or 6×37 configurations for flexibility and strength.

They are used for hoisting heavy loads like steel beams, prefabricated components, and construction materials.

A rope must be retired if 5% of its wires are broken within six rope diameters, or if there is visible corrosion, flattening, or kinking.

The slings used in tower crane are synthetic slings which are ideal for delicate or non-abrasive loads.

Different types are:

• Flat Slings: Suitable for general lifting.

• Round Slings: Higher load capacity, resistant to sharp edges.

For lifting chains, they are made of high-strength alloy steel (e.g., Grade 80 or 100) for durability and heat resistance.

Connectors and Accessories

Shackles

There are 4 shackles typically used in tower crane:

D-Shackles: Designed for vertical loads; widely used for direct hook connections.
Bow Shackles (Omega-Type): U-shaped for multi-directional loads, ideal for irregularly shaped objects.
Quick-Release Shackles: Equipped with spring pins for rapid assenble and disassenble in temporary setups.
Screw Pin Shackles: Threaded pins for permanent or heavy-duty connections (e.g., tower crane anchoring).

Hooks

Hooks used in tower cranes are:

Single Hooks: For moderate loads.
Double Hooks: Provide balanced lifting for heavy objects.
Swivel Hooks: Allow 360° rotation to prevent rope twisting.

Disclaimer: Tower crane rigging systems require meticulous component selection, adherence to safety standards, and integration of advanced control technologies. For comprehensive guidelines, refer to standards such as JGJ 196-2010 and ASME B30.26.

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Frequently Asked Questions

What are the turnbuckles used in tower cane?

Turnbuckles, also known as rigging screws, are critical tension-adjusting components in tower crane systems.

They consist of a threaded sleeve and two opposing threaded rods, enabling precise length adjustment to maintain optimal cable or structural tension.