Flange Bolts

Hex Flange Bolt Types

• Serrated flange bolts have teeth machined into the underside of the flange. The serrations bite into the mating surface under torque, which causes it to resist loosening caused by vibration. These are used in automotive, heavy equipment, and general machinery applications.
• Non-serrated flange bolts provide the load distribution benefit of the flange without the locking action. Used in assemblies where the mating surface can't be marred.
• 12-point flange screws are stocked in inch sizes from 1/4-20 through 3/4-10 in Grade 8, with stainless options on select sizes. The 12-point drive allows higher torque application in tighter spaces compared to a standard hex head.
• Metric hex flange bolts are available from M5 through M20 in property classes 8.8 and 10.9, with stainless and zinc finishes on select sizes.

Grades, Materials, and Finishes

Fastco stocks flange bolts in the following grades and materials:

• Grade 5: Medium-strength inch-series flange bolts for general industrial and automotive use. Available in plain, zinc, and hot-dipped galvanized finishes.
• Grade 8: Higher tensile strength for demanding applications. The majority of our inch flange bolt inventory is Grade 8, available in plain and zinc finishes across a wide size range.
• Metric 8.8: The metric equivalent of approximately Grade 5. Stocked in M5 through M16 for general assembly and equipment applications.
• Metric 10.9: Higher-strength metric flange bolts for structural and equipment use. Available in M12 through M20, with zinc finish on select sizes.
• 18-8 stainless steel: For outdoor, marine, and light chemical environments where corrosion resistance is required without sacrificing strength.
• 316 stainless steel: Stocked in M12 for applications requiring higher corrosion resistance, including saltwater and chemical exposure.
• Zinc-plated: Available across Grade 5, Grade 8, and metric sizes for general industrial use with moderate corrosion resistance.
• Hot-dipped galvanized: Available on select Grade 5 sizes for exterior and high-moisture applications.

Industrial Applications for Flange Bolts

Flange bolts are used in applications that require vibration resistance, or better load distribution than standard bolts provide. The integrated flange eliminates the need to add a separate washer step on production lines, which can increase overall production speeds. Common industrial uses for flange bolts include:

• Automotive and powertrain assembly
• Heavy equipment and machinery manufacturing
• Construction equipment and structural fabrication
• OEM and production line fastening
• Agricultural and marine equipment

Choosing the Right Flange Bolt

• Serrated vs Non-Serrated: For vibration-prone assemblies, serrated is almost always the preferred choice, unless the mating surface is soft or can't be scratched.
• Grades: Grade 8 is used for most high-load applications. Grade 5 is a common choice for lighter-duty jobs.
• Materials: Stainless or hot-dipped galvanized are typically required for applications that require exposure to moisture or corrosive chemicals. For metric assemblies, 10.9 is used for higher-strength applications, and 8.8 is used for general-purpose applications.

Custom Flange Bolts for Specialized Applications

If your application has specific torque, coating, or dimensional requirements that aren't covered by our standard inventory, Fastco's custom threading and cutting services can help. Contact us to discuss options.

Contact Fastco for Flange Bolt Wholesale Pricing

Contact us or request a quote online to discuss bulk pricing, available sizes, and lead times for flange bolts. Looking for other fasteners? Check out our full selection of bolts, washers, and more.