Hexagonal Bolts: Specifications, Grades, and Standards

Introduction to Hexagonal Bolts

Hexagonal bolts, commonly referred to as hex head bolts, are a fundamental component in a variety of fastening applications. These bolts are the industry standard for forged head fasteners, known for their hexagonal heads which provide excellent grip and torque. In this guide, we will delve into the specifications, grades, and standards that define hexagonal bolts, ensuring you have a comprehensive understanding of their applications and characteristics.

Specifications and Grades

Hexagonal bolts come in a range of specifications and grades to meet various industrial requirements. Some of the most common grades include ASTM A307 Grade A and F1554 Class 36. These grades determine the bolt's tensile strength and suitability for different applications. For instance, ASTM A307 Grade A bolts are standard hex head bolts used in general-purpose applications, while F1554 Class 36 bolts are used in construction and structural applications.

For specifications that require a heavy hex pattern, such as ASTM A307 Grade B, A325, and A490, it is crucial to refer to the dimensional tolerances for heavy hex bolts or structural bolts. These specifications ensure that the bolts can withstand higher loads and provide greater durability in demanding environments.

Diameter, Length, and Finishes

Hexagonal bolts are available in diameters ranging from 3/8" to 1-1/2" and lengths of up to 30 inches. The choice of diameter and length depends on the specific requirements of the application. Additionally, hex bolts come in different finishes, including plain and hot-dip galvanized. The hot-dip galvanized finish provides enhanced corrosion resistance, making it ideal for outdoor and marine applications.

Thread Lengths and Standards

The thread length of hexagonal bolts is another critical aspect to consider. For bolts with a length of 6 inches or less, the standard thread length is calculated as (2 x diameter) + 1/4 inch. For bolts longer than 6 inches, the thread length is (2 x diameter) + 1/2 inch. It's important to note that most stock hex bolts that are 10 inches or longer will typically have 6-inch threads.

Understanding these thread length standards ensures that the bolts provide the necessary grip and stability for various fastening applications, preventing issues such as loosening or failure under load.

Conclusion

Hexagonal bolts play an essential role in numerous industries, offering reliability and strength in fastening applications. By understanding the different specifications, grades, diameters, lengths, and finishes, you can select the appropriate hex bolt for your specific needs. Whether you require standard hex head bolts for general use or heavy hex bolts for structural applications, following the industry standards and guidelines will ensure optimal performance and durability.