What are Hex Nuts? FAQ and More

What are Hex Nuts? FAQ and More

Hex nuts are a fundamental component in a wide range of construction and DIY projects, yet they often go unnoticed despite their critical role in securing bolts and other fasteners. Whether you're a seasoned professional or a DIY enthusiast, understanding the various types, sizes, and applications of hex nuts can significantly impact the success and durability of your work. In this guide, we'll delve into everything you need to know about hex nuts—from their basic function and types to selection criteria and installation tips.

What are Hex Nuts?

Hex nuts are six-sided fasteners with an internal thread that is used in conjunction with a bolt or a screw to secure multiple parts together. Their hexagonal shape allows for easy tightening and loosening using standard tools such as wrenches and sockets. Hex nuts are a staple in construction, machinery, and a variety of DIY projects due to their versatility and strength.

What are Hex Nuts Used For?

Hex nuts are primarily used to fasten parts together by threading onto a bolt, creating a strong and reliable joint. They are found in countless applications, from assembling furniture and building structures to securing machinery and automotive parts. Their ease of use and availability in various materials and sizes make them suitable for both temporary and permanent connections in diverse environments.

What is the Difference Between a Heavy Hex Nut and a Hex Nut? 

The primary difference between a heavy hex nut and a standard hex nut is the size and strength. Heavy hex nuts have larger widths and thicker walls, providing greater strength and resistance to stress. This makes them ideal for high-pressure and heavy-duty applications where a standard hex nut might fail. They are commonly used in industrial and structural applications where additional durability is required.

Types of Hex Nuts

  • Standard Hex Nuts: The most common type, used for general fastening purposes.
  • Heavy Hex Nuts: Larger and thicker, providing extra strength for heavy-duty applications.
  • Lock Nuts: Designed to prevent loosening under vibration or torque, often featuring a nylon insert (also known as a nyloc nut).
  • Jam Nuts: Thinner than standard hex nuts, used as a locking device to prevent another nut from loosening.
  • Flange Nuts: Have a built-in washer to distribute pressure evenly and prevent damage to the surface being fastened. 

Grades of Hex Nuts

In the United States, Hex nuts are generally graded by ASTM International, formerly known as the American Society for Testing and Materials, to standardize aspects like material composition, mechanical properties, and testing methods. Other organizations, especially internationally, can and will have different grades that can be equivalent to some of the ASTM grades. For more information on different testing organizations, see our article.

  • A563 Grade A Heavy Hex Nuts
    • Applications: Suitable for general-purpose structural fastenings, including light to medium-duty construction, machinery assembly, and various DIY projects.
    • Specifications: ASTM A563 Grade A covers the requirements for carbon and alloy steel nuts.
    • Properties: Made from low to medium carbon steel, providing adequate strength and durability for non-critical applications. These nuts are typically not quenched and tempered, offering a balance of cost-effectiveness and performance for general use.
  • Grade 2H:
    • Applications: Commonly used in structural applications such as bridges, buildings, and other heavy construction due to its high strength.
    • Specifications: ASTM A194 Grade 2H specifies the requirements for carbon and alloy steel nuts designed for high-pressure and high-temperature service.
    • Properties: Made from medium carbon steel, quenched and tempered, providing high tensile and yield strength.
  • Grade DH: 
    • Applications: Utilized where higher strength fasteners are required, such as in heavy construction and steel structures.
    • Specifications: ASTM A563 Grade DH specifies the requirements for heavy hex nuts made from medium carbon steel.
    • Properties: Offers higher strength than Grade 2H, making it suitable for critical structural connections.
  • Grade C:
    • Applications: Suitable for general-purpose structural fastenings, including construction machinery and equipment assembly.
    • Specifications: ASTM A563 Grade C covers the requirements for carbon and alloy steel nuts.
    • Properties: Made from medium carbon steel, quenched and tempered, providing a balanced combination of strength and toughness.
  • Stainless Steel:
    • Applications: Ideal for harsh environments such as marine, food processing, and chemical industries due to its high corrosion resistance.
    • Specifications: ASTM A194 Grade 8 specifies the requirements for stainless steel nuts, with various grades like 304 and 316 offering different levels of corrosion resistance and mechanical properties.
    • Properties: Known for excellent corrosion resistance, these nuts are suitable for applications where exposure to moisture and corrosive substances is a concern.

How to Remove a Stripped Hex Nut

Removing a stripped hex nut can be challenging, but there are several methods  that can help:

  • Use Pliers or a Vice Grip: These tools can often grip the nut tightly enough to turn it.
  • Cut a Slot: Use a Dremel tool to cut a slot into the nut, then use a flat-head screwdriver to turn it.
  • Nut Splitter: A specialized tool that splits the nut without damaging the bolt.
  • Heat and Lubrication: Apply penetrating oil to loosen rust and corrosion, and use heat to expand the metal slightly, making it easier to turn.

Purchasing Hex Nuts

  • Size and Thread Pitch: Ensure compatibility with the bolts or screws you are using.
  • Material and Finish: Choose based on the application environment—stainless steel for corrosion resistance, or zinc-plated for general use.
  • Grade: Select the appropriate grade based on the required strength and load-bearing capacity.
  • Quantity: Determine the number of hex nuts needed for your project, buying in bulk can often save money. 


Understanding the various types, grades, and applications of hex nuts can significantly enhance the quality and durability of your projects, whether they are DIY endeavors or professional constructions. Hex nuts are indispensable components that provide critical fastening solutions across numerous industries. By selecting the right hex nut based on material, grade, and specific requirements, you ensure reliable and long-lasting connections. Remember to follow proper installation and maintenance practices to maximize performance and safety. For all your hex nut needs, from standard to heavy-duty applications, our extensive range has you covered. Explore our selection and make informed choices to suit your project needs.

Further Questions About Hex Nuts

We offer a wide variety of fasteners and it can be daunting to decide which product best suits your needs. Our team of experts has a depth of knowledge in the fastener industry. If you have any additional questions be sure to reach out and we'll be glad to help.

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