What Are the Grades of the Chain?
When purchasing and using welded chains, we often refer to chain grades such as G30, G43, G70, G80, G100, and G120. These codes mean the tensile strength of different chains and are important parameters for measuring their strength and suitability for various applications. In various industrial, transportation, and everyday applications, selecting the correct chain grade not only affects work efficiency but also directly impacts safety during use. For example, G30 chains are made of carbon steel and are generally used for light-duty fixed or decorative applications, while the G80 and higher grade chains are made of alloy steel and are specifically designed for lifting and heavy duty applications.
This article will fully explain to you the features and uses of each grade of the welded link chain, help you understand their differences, so that you can make the most correct choices when purchasing and using different types of chains.
How Chain Grades Are Classified
The grades of chains are primarily classified based on their material, manufacturing process, and tensile strength. This grading system applies exclusively to welded steel chains and is not intended for stainless steel chains or weldless chains.
The “G” means “Grade,” and the number after it means the minimum tensile strength grade of the chain’s material. For example, G80 chain means the lowest tensile strength of its material is 550 MPa, about 80000 Psi.
Second, the low grade chains are usually made of carbon steel, such as G30, G43, and G70 chains, while G80 and higher grade chains use alloy steel with higher strength and toughness, which requires strict heat treatment processes.
Additionally, in some international standards (such as ISO 3076, EN 818, ASME B30.9, etc.), there are also detailed rules and requirements for the material, dimensions, and performance of each grade, to ensure the chains can be the same standard all over the world.
Detailed Explanation of Chain Grades and Applications
G30 Proof Coil Chain
G30 chain is made of low carbon steel, with low tensile strength, about 30000 Psi, and the surface is mostly galvanized or self-color.
The feature of this chain is low price, focusing on flexibility and low cost, not high strength. It is mainly used for some low load applications, such as:
- Light load fixingsuch as farm tools, fence gates, sheds, garden facilities.
- Light mooringor buoy of small boats and docks (not heavy marine work).
- Decorative or display chain (commercial or retail display).
Because the strength of G30 chain is low, it not rated for any overhead lifting, and it is not suitable for impact load, or high wear conditions.
G43 High Test Chain
G43 chain is made of high carbon steel, so its strength is much higher than G30 chain, the tensile strength is about 43000 Psi. It can be used for some higher load applications, such as cargo binding, trailer tie-down, light towing, and temporary fixing at construction sites.
The G43 chain is also often be used in the transportation industry in North America and Australia, etc., but this is not the specified grade for “transport chain” (the transport chain grade is G70). So, when the budget is limited and it does not involve DOT road inspection or weighing enforcement, G43 is a more economical choice. If it involves highway control and heavy goods, please choose G70 first.
In addition, because the toughness and safety factor of the G43 chain do not meet the lifting standard, it is also not rated for high-altitude lifting work.
G70 Transport Chain
G70 chain is widely used for securing cargo during transport. It is usually made of high carbon steel and has been heat treated, the tensile strength is about 70000 Psi.
The surface of G70 chain is usually galvanized and treated with yellow chromate passivation, with good corrosion resistance, easy identification, and helps with road inspection, improving safety. For example, in the U.S. DOT transport rules, when trucks tie down lumber and steel coils, they need to use G70 transport chains, and the yellow coating makes them easy to identify during roadside inspections.
G80 Alloy Lifting Chain
The G80 chain is made of high-quality alloy steel (added elements such as manganese, boron, chromium, and molybdenum, etc.) and goes through strict heat treatment. This grade chain has excellent strength and toughness, its tensile strength is approximately 80,000 psi, making it the most widely used chain in the lifting and hoisting industry. The surface of G80 chain is usually blackened to enhance wear resistance and prevent light reflection interference.
The G80 chain meets the requirements of various international standards such as ISO, EN 818-2, AS 3775, and ASME B30.9. Its safety factor is typically 4:1 or higher, making it suitable for heavy duty equipment, construction sites, cranes, overhead lifting, and high-impact applications.
G100 Premium Alloy Chain
G100 chain is made of higher strength alloy material and needs a stricter heat treatment process. Its WLL is more than 20% higher than a G80 chain of the same diameter and size, and it is lighter in weight. The surface of the G80 chain is usually blue, making it easy to distinguish.
The safety factor of G100 chain is at least 4:1. It meets lifting chain standards such as EN, ISO, ASME, and AS etc. It is mainly used for high-strength lifting and for various lifting or rigging applications with stricter load and safety requirements.
G120 Ultra High Strength Chain
G120 chain uses a more complex alloy material and heat treatment process, with further increased strength. It has stricter requirements for material purity, welding quality, and the uniformity of the heat treatment. The surface often has a green coating as an identification color, but the color is not specified by international standards, and the permanent marking on the chain and the certificate should be taken as the standard.
G120 chain meets the standards of high grade lifting chain and rigging, and it has full traceability (furnace batch number, heat treatment batch, inspection report). In some high risk or high value projects, it may also require third-party witness testing and non-destructive testing (magnetic particle or ultrasonic) records.
When choosing the right grade of chain, you need to consider many factors. So, besides the material, surface treatment, and use environment of the chain, you also need to pay special attention to the chain grade. Because of the difference in material and production process, chains of different grades have obvious differences in WLL and MBF, and these decide their range of use:
- Light Load, Daily Use: Choose G30, G43, etc. They are cheap, with high toughness, very suitable for agriculture, fences, decoration, and fixing light goods in daily use.
- Transport and Heavier Load: Choose G70. The G70 transport chain is the standard choice in the transport industry, especially in trailers or truck transportation for cargo tie-down. The yellow coating can prevent corrosion during long outdoor use and make it easy to identify quickly.
- Industrial Lifting: Choose G80 or higher grade chain. This type of chain meets international lifting standards, has excellent toughness, strength, and impact resistance, and is suitable for all kinds of rigging, heavy equipment lifting, and frequent lifting and lowering, ensuring safety during use.
- Higher Strength and Safety Needs: Choose G100 or G120 grade. They have higher strength and lighter weight than the G80 chain. For the same diameter and size, they provide greater safety and higher load capacity than the G80 chain.
In Summary, selecting the correct types of chain grade ensures optimal performance, compliance with standards, and safe, reliable operation for your specific application. For more detailed guidance or specifications, please contact Tuohai.
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