1/2" UNC Stainless Steel Grade 316 Hex Head Bolts, manufactured to DIN 931 standards, are robust fasteners designed for applications that require both high strength and excellent corrosion resistance. These bolts are commonly used in harsh environments such as marine, chemical, and outdoor industrial applications due to the superior properties of 316 stainless steel.

Characteristics

1. Material:
   • Grade 316 Stainless Steel: Known for its excellent resistance to corrosion, particularly in chloride-rich environments (like seawater) and industrial atmospheres containing acidic compounds.
2. Thread Type:
   • UNC (Unified National Coarse): The 1/2" UNC thread features 13 threads per inch (TPI), providing a coarser thread profile that offers easier installation and a stronger hold in softer materials.
3. Standards:
   • DIN 931: This standard specifies the dimensions and mechanical properties for partially threaded hex bolts, ensuring uniformity and reliability.

Dimensions and Spanner Size

Below are the detailed dimensions and spanner size for a 1/2" UNC hex head bolt made to DIN 931:

1. Diameter: 1/2 inch (12.7 mm)
2. Thread Pitch: 13 threads per inch (TPI) for UNC
3. Hex Head Dimensions:
   • Across Flats (AF): 3/4 inch (19.05 mm)
   • Across Corners (AC): Approximately 0.866 inch (22.02 mm)
   • Head Height (k): Approximately 0.323 inch (8.20 mm)
4. Spanner Size: 3/4 inch (19.05 mm)
5. Shank Length: Variable, depending on the overall length of the bolt, with partial threading.
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 shipbuilding, dock construction, and other applications exposed to seawater.
2. Chemical Processing:
   • Used in chemical plants and industries where exposure to corrosive chemicals is frequent.
3. Construction:
   • Suitable for outdoor structures, bridges, and buildings, particularly in coastal or industrial environments.
4. Automotive and Aerospace:
   • Applied in critical areas exposed to harsh environmental conditions.

Benefits

• Corrosion Resistance: Grade 316 stainless steel contains molybdenum, which significantly improves its resistance to corrosion and oxidation, particularly in chloride-rich and industrial environments.
• Strength: Offers high tensile strength, making it suitable for high-stress applications.
• Durability: Long-lasting and requiring minimal maintenance, providing a cost-effective solution for long-term applications.

Installation Tips

• Spanner/Wrench Size: Use a 3/4 inch spanner or wrench to tighten the hex head bolt.
• Pre-Drilling: When used in wood or other softer materials, pre-drilling a pilot hole can help prevent splitting and ensure a secure fit.
• Torque Specifications: Adhere to the appropriate torque specifications to avoid over-tightening, which could damage the bolt or the material being fastened.

Conclusion

1/2" UNC stainless steel grade 316 hex head bolts made to DIN 931 are essential for applications that require high durability and resistance to corrosion. Their robust construction and adherence to DIN 931 standards ensure reliability and consistency in demanding environments. These bolts are ideal for marine, chemical, construction, and industrial applications, providing a secure and long-lasting fastening solution.