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ASTM A193 B7, B7M, B8, & B8M PTFE Heavy Hex Bolts

High-quality carbon steel bolts have been a mainstay of durable goods manufacturing, agricultural machinery, and transportation operations for decades. Our ASTM-A193 B7 heavy hex bolts are an excellent fit for countless industries, ranging from HVAC and construction to marine and petrochemical. ASTM-A193 B7, B7M, B8, & B8M heavy hex bolts are available in stainless or coated in teflon (PTFE), hot dipped galvanized, and zinc or cadmium plated configurations for environments where moisture and corrosion are key considerations.

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Why Choose ASTM-A193 B7 Teflon Blue Cap Screw?

Heavy hex bolts are especially popular in durable goods manufacturing, assembly, and fabrication because of their larger bearing surface area. Hex bolts with the ASTM-A193 B7 and B8 rating offer many advantages in demanding environments:

High tensile strength: A193 B7 features chrome-molybdenum steel alloy that undergoes quenching and tempering. This material offers at least 125 ksi of tensile strength, and a maximum hardness of 35 HRC. B7 headed or non-headed bolts are produced from 4140 bar stock or forging stock.

High temperature resistance: The medium-carbon, heat-treated nature of A193 B7 hex bolts makes them ideal for high-temp automotive, aerospace, semiconductor, manufacturing, and oil/gas applications, including flange bolts.

Higher torque capacity: Steel alloy heavy hex bolts support greater torque due to their larger head size and bearing surface, making this design essential for many structural bolting needs.

Vibration resistance: The high-temp, high-strength and shock-distributing properties of ASTM-A193 B7 heavy hex bolts make them ideal for applications where vibrations are common, such as heavy machinery and bridges.

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Your B7 Hex Bolt Supplier

At Brazos Fasteners, we’re a trusted resource for industrial and commercial bolts, nuts, threaded rods, and countless other heavy-duty components. With over 30 years as a stainless B7 hex bolt distributor, we deliver precision, quality, and exceptional customer service every time. Request a quote for ASTM-A193 B7 heavy hex bolts with your project specs right away.

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Frequently Asked Questions

ASTM A193 heavy hex bolts are high-strength fasteners made from heat-treated chromium-molybdenum alloy steel (AISI 4140/4142). The “heavy hex” designation refers to a larger head size than standard hex bolts, which provides a greater bearing surface area to distribute clamping loads. These bolts are specifically engineered for high-pressure and high-temperature service in demanding industrial environments.

Because of their high tensile strength and heat resistance, these fasteners are commonly used in:

  • Petrochemical & Refining: Flange bolting for pipelines and pressure vessels.
  • Power Generation: High-heat equipment and turbine components.
  • Midstream Oil & Gas: Compression systems and offshore platforms.
  • Construction & Infrastructure: Structural bolting where vibration resistance and high torque capacity are required.

Grade B7 bolts undergo a quenching and tempering process to achieve their strength. For diameters up to 2-1/2 inches, they typically feature:

  • Minimum Tensile Strength: 125,000 psi (125 ksi).
  • Minimum Yield Strength: 105,000 psi (105 ksi).
  • Maximum Hardness: 35 HRC (Rockwell C).
  • Temperature Range: Generally reliable for service up to 750°F–840°F.

The primary difference is the dimensional width across the flats and the head height. A heavy hex bolt has a wider head, which allows for higher torque values and prevents the bolt head from “sinking” into the material under extreme tension. This makes them the standard choice for structural and high-pressure piping applications.

As a leading heavy hex bolt supplier, Brazos Fasteners offers several protective coatings to suit your environment:

  • Plain (Black Oxide): Best for high-heat applications where corrosion is not a primary concern.
  • Teflon (PTFE) Coating: Excellent for offshore and chemical environments to prevent seizing and corrosion.
  • Hot-Dipped Galvanized (HDG): Provides a thick layer of zinc for superior atmospheric corrosion protection.
  • Zinc or Cadmium Plating: Ideal for general industrial use with mild corrosive exposure.

Brazos Fasteners specializes in high-quality bolting solutions for the oil, gas, and petrochemical industries. We provide:

  • Expert Knowledge: Guidance on the correct grades and finishes for your specific project requirements.
  • Rapid Delivery: We understand the costs of downtime and prioritize fast turnaround times for critical components.
  • Range of Sizes: We stock a range of imperial sizes in various thread configurations (UNC, UNF, and 8UN).
  • 24/7 Support: Call-out services are available to ensure your operations never stop.

Why Choose Brazos Fasteners?

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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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