ASTM A307 Grade B Half-Thread Hex Bolts, 1/2"-13 X 2-1/4", Black Oxide Finish

Product Name: ASTM A307 Grade B Half-Thread Hex Bolts, 1/2"-13 x 2-1/4", Black Oxide Finish

Product Overview:
Engineered for flanged joints in piping systems with cast iron flanges, our 1/2"-13 x 2-1/4" hex bolts strictly comply with ASTM A307 Grade B specifications. Featuring a partial thread design and a premium black oxide finish, these bolts deliver reliable structural integrity and a professional aesthetic for industrial and mechanical assemblies.

Key Specifications:

• Standard Compliance: ASTM A307 Grade B (Tensile Strength: 60,000 - 100,000 psi / 414 - 690 MPa)

• Thread Size: 1/2"-13 UNC Coarse Thread, Partially Threaded (Half Thread)

• Overall Length: 2-1/4 inches

• Material: Low-Carbon Steel (C ≤ 0.29%, Mn ≤ 1.20%)

• Surface Finish: Black Oxide (Blackening) with anti-rust oil impregnation

• Head Style: Standard Hexagon Head (Compatible with ASME B18.2.1 dimensions)

Black Oxide Finish Advantages:

• Zero Hydrogen Embrittlement: Unlike electroplating, the chemical oxidation process eliminates hydrogen embrittlement risks, ensuring the structural integrity of the bolt under load.

• Dimensional Precision: The ultra-thin Fe₃O₄ film (0.5-1.5μm) does not alter thread tolerances, guaranteeing smooth nut engagement and precise fitment.

• Corrosion & Wear Resistance: Provides a uniform, matte black appearance with moderate rust protection for indoor and dry environments. Enhanced with post-treatment oil sealing for extended durability.