Heavy Duty Flange Bolts 316 Stainless Steel M8-M24 Marine Grade Chemical Resistant Structural Fasteners GB DIN OEM Custom

Beschrijving

What are Flange Bolts ？

Flange bolts feature a built-in circular flange under the head that distributes clamping load across a wider surface area. Common reference standards include DIN 6921 (metric) and SAE J429 (inch). Unlike standard hex bolts requiring separate flat washers, the integrated flange eliminates an assembly step while providing consistent bearing surface and superior resistance to loosening under vibration.

Material

• Stainless Steel: A2-70 (70,000 psi tensile, equivalent to 304 grade) delivers general corrosion resistance for food processing and architectural applications. A4-80 (80,000 psi tensile, equivalent to 316 grade) provides enhanced resistance to chlorides and marine environments.

• Carbon Steel: Property classes 8.8 (800 MPa tensile) and 10.9 (1040 MPa tensile) offer high strength for automotive and heavy equipment assemblies where load capacity drives selection.

• Alloy Steel: Class 10.9 and 12.9 meet extreme strength requirements for commercial vehicle chassis and suspension components.

Surface Finishes

• Zinc Plated: Delivers 48+ hours salt spray protection. First choice for carbon steel flange bolts in automotive and general industrial applications.

• Geomet/Dacromet: Provides zinc-aluminum coating for high-corrosion environments. Resists 500+ hours salt spray without hydrogen embrittlement risk. Preferred for European automotive specifications.

• Passivated: Enhances stainless steel’s natural oxide layer, maximizing corrosion resistance for medical and food contact applications.

• Yellow Zinc: Offers enhanced corrosion protection with distinctive gold appearance. Common in European and Asian automotive assemblies.

• Plain (Uncoated): Standard for stainless steel; specify for high-temperature environments where coatings may degrade.

Specification Parameters

• Diameter: M5 through M20 metric; 1/4-inch through 3/4-inch imperial

• Length: 8mm to 200mm metric; 3/8-inch through 8-inch imperial

• Flange Diameter: Typically 2x to 2.5x shank diameter, providing broad load distribution without separate washer

• Flange Serrations: Optional undersurface serrations grip mating surface, preventing loosening under vibration

• Head Height: Standard hex height with integrated flange; external drive (hex) standard

• Thread: Coarse thread standard; fine thread available for vibration-sensitive applications

Vertical Application Scenarios

Automotive Engine Assembly: Flange bolts secure timing covers, oil pans, and accessory mounts where space constraints limit washer placement. The integrated flange distributes clamp load evenly across aluminum castings, preventing galling and maintaining seal compression.

HVAC Equipment Manufacturing: Roof-top air handlers use stainless steel flange bolts for panel fastening. The wide flange bears on thin-gauge sheet metal without pull-through, while the serrated underside locks against vibration from fans and compressors.

Agricultural Implement Assembly: Tillage equipment and planter frames require fasteners that withstand constant shock loads. Flange bolts with serrated bearing surfaces maintain clamp tension through field operations, eliminating periodic retorquing during harvest season.

Heavy Truck Chassis: Suspension components and crossmembers use flange bolts for simplified assembly. The integrated design speeds production line installation while providing consistent load distribution across structural members.

Customer Case

Situation: A commercial truck manufacturer experienced warranty claims for loosening suspension fasteners. Standard hex bolts with separate flat washers required two-handed assembly and showed inconsistent clamp load due to misplaced or dropped washers on the assembly line.

Task: Engineering required a fastening solution that eliminated washer handling, maintained consistent clamp load across all joints, and resisted loosening under 5+ years of over-the-road vibration.

Action: Supplied M14 x 100mm flange bolts, property class 10.9, Geomet-coated, with serrated bearing surface. The integrated flange eliminated separate washer handling. Serrations provided additional vibration resistance. Geomet coating delivered 500+ hour salt spray protection without hydrogen embrittlement.

Result: The assembly plant reported 20% faster installation times and complete elimination of washer-related line stoppages. Warranty claims for loose suspension fasteners dropped to near zero over three years. The manufacturer now specifies flange bolts across all chassis suspension applications.