5/16" UNC Stainless Steel Grade 316 Hex Head Bolts, made to DIN 931 standards, are durable fasteners widely used in applications requiring high strength and exceptional resistance to corrosion. The combination of UNC threading and grade 316 stainless steel makes these bolts particularly suitable for harsh environments, including marine, industrial, and outdoor settings.

Characteristics

1. Material:
   • Grade 316 Stainless Steel: This material is highly resistant to corrosion, especially in marine and acidic environments. It contains molybdenum, which enhances its resistance to chlorides and other industrial solvents.
2. Thread Type:
   • UNC (Unified National Coarse): The Unified National Coarse thread pattern features fewer threads per inch (TPI) than fine threads, providing a more robust threading profile that is easier to assemble and less prone to stripping.
3. Standards:
   • DIN 931: This German standard specifies the dimensions and mechanical properties for partially threaded hex bolts, ensuring uniformity and reliability.

Dimensions and Spanner Size

Below are the key dimensions and details for a 5/16" UNC hex head bolt conforming to DIN 931:

1. Diameter: 5/16 inch (7.94 mm)
2. Thread Pitch: 18 threads per inch (TPI) for UNC
3. Hex Head Dimensions:
   • Across Flats (AF): 1/2 inch (12.7 mm)
   • Across Corners (AC): Approximately 0.577 inch (14.66 mm)
   • Head Height (k): Approximately 0.200 inch (5.08 mm)
4. Spanner Size: 1/2 inch (12.7 mm)
5. Shank Length: Variable depending on the bolt length, with a partially threaded portion.
6. Thread Length: For bolts up to 125 mm in length, the thread length is 2 x diameter + 6 mm. For bolts longer than 125 mm, the thread length is 2 x diameter + 12 mm.

Applications

1. Marine Applications:
   • Ideal for use in shipbuilding, dock construction, and other environments exposed to saltwater.
2. Chemical Processing:
   • Suitable for use in chemical plants where resistance to corrosive substances is critical.
3. Construction:
   • Used in outdoor structures, bridges, and buildings, particularly in coastal or industrial areas.
4. Automotive and Aerospace:
   • Employed in critical areas exposed to harsh environmental conditions.

Benefits

• Corrosion Resistance: The inclusion of molybdenum in grade 316 stainless steel provides superior resistance to corrosion, making these bolts ideal for harsh environments.
• Strength: Offers high tensile strength and durability, suitable for high-stress applications.
• Durability: Long-lasting and requires minimal maintenance, making it a cost-effective choice for long-term applications.

Installation Tips

• Spanner/Wrench Size: Use a 1/2 inch spanner or wrench to tighten the hex head bolt.
• Pre-Drilling: When used in wood or other soft materials, pre-drilling a pilot hole can help prevent material splitting and ensure a secure fit.
• Torque Specifications: Follow appropriate torque specifications to avoid over-tightening, which could damage the bolt or the material being fastened.

Conclusion

5/16" UNC stainless steel grade 316 hex head bolts made to DIN 931 are essential components for applications requiring high durability and corrosion resistance. Their robust construction and adherence to DIN 931 standards ensure reliability and consistency in demanding environments. Whether used in marine, chemical, construction, or industrial settings, these bolts provide a secure and long-lasting solution for a variety of critical applications.