Chain grade is a term used to describe the strength and durability of steel chains used in various applications such as lifting, towing, and securing heavy loads. Chain grade is determined by a set of industry standards that define the minimum requirements for tensile strength, elongation, and hardness.
The most commonly used standard for chain grade in the United States is the National Association of Chain Manufacturers (NACM) standard, which defines four different grades of chains: Grade 30, Grade 43, Grade 70, and Grade 80. Each grade of chain has specific properties that make it suitable for different applications.
Grade 30 chain is the most basic and least strong of the four grades. It is commonly used for general-purpose applications such as agriculture, construction, and light-duty towing. Grade 30 chains have a maximum working load limit of 2,600 pounds and a minimum tensile strength of 9,800 pounds per square inch (psi).
Grade 43 chain is a medium-strength chain and is commonly used for heavier-duty applications such as logging, marine, and trucking. Grade 43 chains have a maximum working load limit of 3,900 pounds and a minimum tensile strength of 13,500 psi.
Grade 70 chain is a high-strength chain that is commonly used for heavy-duty applications such as transport chains and load binders. Grade 70 chains have a maximum working load limit of 6,600 pounds and a minimum tensile strength of 18,000 psi.
Grade 80 chain is the strongest of the four grades and is commonly used for the most demanding applications such as heavy machinery, industrial equipment, and crane chains. Grade 80 chains have a maximum working load limit of 8,800 pounds and a minimum tensile strength of 24,000 psi.
In addition to the NACM standard, there are other international standards used to define chain grades such as the European standard, which defines chain grades as grades 2, 3, 4, and 5. It is essential to choose the appropriate chain grade for the specific application to ensure safety and prevent damage to the equipment.
In conclusion, chain grade is a critical factor in determining the suitability of steel chains for different applications. Choosing the appropriate chain grade based on the application’s requirements is essential for safety, durability, and efficiency. The NACM standard defines four different chain grades, each with specific properties that make them suitable for different applications. It is important to follow the industry standards and guidelines when selecting and using steel chains to ensure their proper use and safety.