Hex Flange Bolt

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Hex Flange Bolt

Hex flange bolts are high-strength fasteners featuring a hexagonal head with an integrated washer-like flange at the base. The flange distributes the clamping load over a larger surface area, reducing the need for a separate washer and minimizing stress concentration on the connected parts. These bolts are widely used in automotive, machinery, and structural applications where vibration resistance, torque retention, and load distribution are critical.

Types of Hex Flange Bolts
  • Standard Hex Flange Bolt: Hex head with flat flange for general applications
  • High-Strength Hex Flange Bolt: Alloy steel or stainless steel for critical and industrial applications
  • Metric and Inch Series: Available in various thread standards (UNC / UNF / Metric)
  • Stainless Steel Hex Flange Bolt: Corrosion-resistant for outdoor or harsh environments
  • Flanged Shoulder Bolt: Provides precise alignment and load support in assemblies

Applicable Standards

Dimensional Requirements:
  • ISO 4161 – Hexagon head bolts with flange
  • DIN 6921 – Hex flange bolts
  • ASME B18.2.1 – Hex bolts (general specifications)
  • ASTM A193 / A320 – Alloy steel high-strength bolts
  • SAE J429 – Automotive grade bolts
Material Grades:
  • Carbon Steel (ASTM A307): General-purpose fasteners
  • Alloy Steel (ASTM A193 B7 / B16): High-strength industrial applications
  • Stainless Steel (AISI 304 / 316, ASTM A193 B8 / B8M): Corrosion-resistant
  • High-Performance Alloy (Inconel / Alloy 625):Extreme temperature and corrosive environment
Material Grades (Commonly Used)

High Tensile, Stainless Steel, Alloy Steel, Inconel, Incoloy, Hastelloy, Monel, Silicon Bronze, Phosphor Bronze, Aluminium Bronze, Nickel, Brass, Copper, Copper Nickel,Duplex, Super Duplex, Titanium Alloys, CB20, Nitronic, Nimonic, ASME, ASTM etc…

Typical Specifications
  • Diameter Range: M6 to M36 / ¼” to 1-½”
  • Thread Type: UNC / UNF / Metric (Coarse & Fine)
  • Head Type: Hexagonal with integrated flange (typically 120°–130°)
  • Shank Type:Fully or partially threaded as per application
  • Flange Diameter: Typically 1.5–2× bolt diameter (varies with standard)
Surface Protection / Coating:
  • PTFE Coated (Blue, Yellow, Red, Green & Black)
  • Hot Dip Galvanized
  • Yellow Zinc Plated
  • Blue Zinc Plated
  • Molykote
  • Aluminium Zinc Flake Coated
  • Black Phosphate
  • Zinc Plated
  • Nickel Plated
Engineering Applications
  • Automotive assemblies (engines, chassis, suspensions)
  • Machinery and industrial equipment
  • Structural steel connections
  • Heavy equipment and construction machinery
  • Oil & gas and petrochemical installations
Performance & Key Features
  • Integrated flange distributes load and reduces the need for washers
  • High vibration and torque resistance
  • Reduces stress concentration in mating surfaces
  • Suitable for high-strength and corrosive environments
  • Simplifies installation and improves assembly speed
Design Considerations
  • Ensure proper flange seating for uniform load distribution
  • Torque according to material and bolt grade to prevent over-tightening
  • Consider flange thickness in assembly design for load transfer
  • Select material and coating based on environment and temperature conditions