What sizes of flange bolts are available?
Oct 02, 2025
When it comes to flange bolts, one of the most common questions we receive as a flange bolts supplier is about the available sizes. Flange bolts are essential components in various industries, from construction to automotive, and having the right size is crucial for ensuring a secure and reliable connection. In this blog post, I'll delve into the different sizes of flange bolts that are available in the market and how you can choose the right one for your specific needs.
Standard Sizes of Flange Bolts
Flange bolts come in a wide range of sizes to accommodate different applications. The size of a flange bolt is typically determined by its diameter, length, and thread pitch. In the metric system, the diameter of a bolt is measured in millimeters (mm), while in the imperial system, it is measured in inches.
Metric Sizes
Metric flange bolts are widely used in many countries around the world. Some of the common metric sizes include M6, M8, M10, M12, M16, M20, and M24. Here's a brief overview of these sizes:
- M6: This is a relatively small flange bolt with a diameter of 6 mm. It is often used in light - duty applications, such as in electronics or small machinery.
- M8: With a diameter of 8 mm, the M8 flange bolt is suitable for medium - duty applications. It can be found in automotive parts, furniture assembly, and some construction projects.
- M10: A 10 - mm diameter bolt, the M10 is commonly used in more heavy - duty applications compared to the M8. It is often used in construction, industrial machinery, and automotive engines.
- M12: The M12 flange bolt has a 12 - mm diameter and is used in a variety of heavy - duty applications, including large machinery, structural connections, and bridge construction.
- M16: This 16 - mm diameter bolt is suitable for very heavy - duty applications. It is commonly used in large industrial equipment, power generation plants, and heavy construction projects.
- M20 and M24: These larger metric flange bolts with diameters of 20 mm and 24 mm respectively are used in extremely heavy - duty applications where high strength and load - bearing capacity are required.
Imperial Sizes
In the imperial system, common sizes of flange bolts include 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 3/4", and 1".
- 1/4": A small flange bolt with a 1/4 - inch diameter, it is often used in light - duty applications, similar to the M6 in the metric system.
- 3/8": This 3/8 - inch diameter bolt is suitable for medium - duty applications, comparable to the M8 in the metric system.
- 1/2": With a 1/2 - inch diameter, the 1/2" flange bolt is used in heavy - duty applications, similar to the M12 in the metric system.
- 3/4" and 1": These larger imperial flange bolts are used in extremely heavy - duty applications, similar to the M20 and M24 in the metric system.
Length Variations
In addition to the diameter, the length of a flange bolt is also an important factor. The length of a flange bolt is measured from the underside of the flange to the end of the bolt. Flange bolts are available in a wide range of lengths, typically starting from as short as 10 mm (in the metric system) or 3/8" (in the imperial system) up to several hundred millimeters or inches. The length you choose depends on the thickness of the materials you are joining and the amount of thread engagement required.
Thread Pitch
The thread pitch of a flange bolt refers to the distance between adjacent threads. In the metric system, thread pitch is measured in millimeters, while in the imperial system, it is expressed as the number of threads per inch. For example, a metric M8 bolt may have a thread pitch of 1.25 mm, while an imperial 1/4" bolt may have 20 threads per inch. The correct thread pitch is crucial for ensuring a proper fit between the bolt and the nut or the threaded hole.
Special Sizes and Custom - Made Flange Bolts
While the standard sizes mentioned above are widely available, there are also situations where special sizes of flange bolts are required. For example, in some unique industrial applications or custom - built machinery, non - standard diameters, lengths, or thread pitches may be needed. As a flange bolts supplier, we understand the importance of meeting these special requirements. We offer custom - made flange bolts to meet the specific needs of our customers. Whether you need a flange bolt with a non - standard diameter, a special length, or a unique thread pitch, we can work with you to produce the right product.
Types of Flange Bolts and Their Size Considerations
There are different types of flange bolts, each with its own characteristics and size - related considerations.
Galvanized Flange Bolt
Galvanized flange bolts are coated with a layer of zinc to protect them from corrosion. They are available in all the standard metric and imperial sizes. The Galvanized Flange Bolt is a popular choice for outdoor applications or in environments where the bolts are exposed to moisture or chemicals. When choosing the size of a galvanized flange bolt, you need to consider the same factors as with other types of flange bolts, such as the load - bearing requirements and the thickness of the materials being joined.
Flanged Hexagon Bolts
Flanged hexagon bolts have a hexagonal head and a flange at the base. They are available in a wide range of sizes and are commonly used in applications where a high - torque connection is required. The Flanged Hexagon Bolts are suitable for both light - duty and heavy - duty applications. The size selection for flanged hexagon bolts depends on the application's requirements, including the amount of force that will be applied to the connection.
Hexagon Bolts With Flange
Hexagon bolts with a flange are similar to flanged hexagon bolts but may have different design features. They are also available in various sizes and are used in a variety of applications. The Hexagon Bolts With Flange offer a good balance between strength and ease of installation. When choosing the size of these bolts, you should consider the specific requirements of your project, such as the type of materials being joined and the environmental conditions.
Choosing the Right Size of Flange Bolts
Choosing the right size of flange bolts is a critical decision that can affect the safety and performance of your project. Here are some steps to help you make the right choice:
- Determine the Load Requirements: Calculate the amount of force or load that the flange bolt will need to withstand. This will help you narrow down the appropriate diameter and strength grade of the bolt.
- Measure the Thickness of the Materials: Measure the combined thickness of the materials you are joining. This will help you determine the required length of the flange bolt.
- Consider the Environmental Conditions: If the bolts will be exposed to harsh environments, such as high humidity, chemicals, or extreme temperatures, you may need to choose a bolt with a suitable coating or material.
- Check the Thread Compatibility: Ensure that the thread pitch of the bolt is compatible with the nut or the threaded hole.
Contact Us for Your Flange Bolt Needs
If you are in the market for flange bolts and are unsure about which size or type is right for your application, our team of experts is here to help. We have a wide range of flange bolts in stock, including all the standard metric and imperial sizes, as well as the ability to produce custom - made flange bolts. We can provide you with technical advice, product samples, and competitive pricing. Whether you are a small - scale manufacturer, a large construction company, or an individual DIY enthusiast, we can meet your flange bolt requirements. Contact us today to discuss your project and start the procurement process.
References
- Machinery's Handbook, 31st Edition
- ASTM International Standards for Fasteners
- ISO Standards for Bolts and Nuts