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Views: 0 Author: Site Editor Publish Time: 2025-12-26 Origin: Site
Steel wire rope is composed of multiple individual steel wires twisted into strands, which are then twisted around a core to form the rope. The main components of steel wire rope are the steel wires, strands, core, and the grease used to lubricate the rope.
Three Types of Steel Wire Ropes and Their Applications
6×19+1 Steel Wire Rope: This type is primarily used for guy ropes and stay cables where the rope is not subject to bending and wear. Due to its thicker steel wires, it is durable and resistant to wear but not ideal for use in lifting rope slings.
6×37+1 Steel Wire Rope: Typically used in pulley systems, this type of rope is designed for scenarios where the rope undergoes bending. Its wires are of moderate thickness, making it flexible and suitable for use in lifting slings and pulleys, allowing for efficient lifting operations.
6×61+1 Steel Wire Rope: Ideal for pulley systems, making hoisting ropes, and binding lifting items. Its finer steel wires make it more flexible, which is perfect for making sling connections, but it is less durable and not typically used in environments requiring high wear resistance.
For most lifting operations in construction, 6×37+1 steel wire ropes are commonly used for hoisting slings and lifting tasks.
Break strength, also known as the minimum break strength or nominal break strength, refers to the maximum load a steel wire rope can withstand before breaking under static tension.
In simple terms, it is the theoretical maximum tensile strength a steel wire rope can bear. This value is one of the most critical mechanical performance indicators of steel wire rope, directly affecting the safety of lifting, towing, and hoisting operations.
Common Estimation Formula:
A widely used and sufficiently accurate formula to estimate the break strength of steel wire rope in practical work is:
Break Strength (kg)≈50×(Diameter of Rope)2
Note:
Diameter (D) is measured in millimeters (mm).
The result is in kilograms (kg), which can be converted to tons by dividing by 1000.
Example:
For a steel wire rope with a diameter of 20mm:
50×(20)2=50×400=20,000 kg=20 tons
The working load or safe load is calculated as follows:
Working Load=Safety Factor/Break Strength
The purpose of knowing the break strength is to ensure safety. In practice, steel wire ropes should never be subjected to loads approaching their break strength. To ensure safety, the concept of the safety factor is introduced.
Choosing the Safety Factor:
The safety factor depends on:
Use case: For example, the safety factor for crane lifting ropes, guy ropes, and personnel-carrying equipment varies.
Industry standards: Different countries and industries (e.g., construction, shipping, mining) have specific regulations.
For example, according to HG/T 20201-2017 (Chemical Engineering Construction Lifting Code), the safety factor for lifting ropes or slings is determined based on load size, number of rope strands, bending degree, and the presence of protective devices, typically ranging from 6 to 10.
In GB 50798-2012 (Petrochemical Large Equipment Lifting Code), a safety factor of at least 5 is required for steel wire ropes. However, due to bending, the load-carrying capacity decreases, which requires calculating an efficiency factor of around 0.7-0.8. When considering this, the safety factor is typically between 6.25 and 7.14.
Example:
For a 20mm diameter steel wire rope, with a break strength of 20 tons:
Using a 6x safety factor:
20 tons÷6=3.33 tons
Different binding methods impact the load capacity of the steel wire rope. The angle between lifting slings plays a crucial role: the greater the angle between the slings, the greater the force the sling bears.
The steeper the angle between the slings and the load, the higher the tension the sling experiences.
Steel wire ropes are essential components in lifting and rigging operations. Understanding the types of steel wire ropes, their break strength, and how to calculate working load with appropriate safety factors are crucial for ensuring safety and efficiency in industrial applications. Proper design and application of the right steel wire rope for specific tasks help improve operational safety and durability.
