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ASTM-A325 & ASTM-A490 Heavy Hex Bolts

Structural hex bolts must meet specific requirements established by the American Society for Testing and Materials. Along with grade 8, ASTM A490 heavy hex bolts, ASTM A325 heavy hex bolts are a grade of structural bolt within the F3125 ASTM designation.

Properties of Structural Hex Bolts

ASTM-A325 heavy hex bolts have very specific mechanical, chemical, and configuration requirements and qualities. They can be made in Type 1 medium carbon steel or Type 3 weathering steel. An important distinction between A325 and A490 is that A325 Type 1 bolts can be galvanized. ASTM A490 Heavy Hex Bolts cannot be galvanized due to the potential for hydrogen embrittlement, which could occur during the galvanizing process.

  • A325 heavy hex bolts are made from medium-carbon or medium-carbon alloy steel that is quenched and tempered to achieve the required mechanical properties with a minimum tensile strength of 120,000 PSI for 1” or less diameters and 105,000 PSI for bolts over 1”.
  • A490 heavy hex bolts typically are used for bridges and highway construction. These require a higher minimum tensile strength 150,000 PSI, which makes them stronger than A325 bolts. But higher strengths of steel can also bring in the possibility of stress corrosion and hydrogen cracking.
  • Short overall length (we carry A325 bolts up to 5 inches),
  • A heavy hex head to distribute clamping load over a large surface area
  • Full body diameter
  • A325 diameter ranging from 1/2 inch to 1-1/2 inches, over 1-1/2” diameter fall under the ASTM A449 specification.
  • A325 and A490 Heads stamps are specific markings to identify the different Types 1-3.

Uses for ASTM-A325 and ASTM-A490 Heavy Hex Bolts

Heavy hex bolts are used in steel-to-steel structural connections. They are designed for use in flanges and steel-to-steel connections that require high clamping strength.

Oil and Gas

Oil and gas industries:

  • Pipeline and flange bolting
  • Facility production
  • Bolting in engines, substructures, and mud pumps
Power Generation

Power generation:

  • Construction and maintenance of power plants and transmission stations
  • Anchor bolts for transformers and cooling towers
Construction

Construction:

  • Structural steel in heavy construction projects
  • Heavy equipment engines
Transportation

Transportation:

  • Boat and barge manufacturing and refitting
  • Bolting of bridges and highways
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About Brazos Fasteners

Our focus is to provide high-quality fasteners in whatever time frame you need them with expert customer service. The success of various organizations with diverse backgrounds relies heavily on our products, which are held to high standards.

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