Carbon Steel Bolts, Studs, and Threaded Rod 60 000 PSI Tensile Strength

A307: Standard Specification for Carbon Steel Bolts, Studs, and Threaded Rod (60,000 PSI Tensile Strength)

When specifying fasteners for general structural applications, piping systems, and machinery, understanding the foundational standards is paramount. ASTM A307 is an essential specification that provides engineers and designers with the critical requirements for common carbon steel bolts, studs, and threaded rod, ensuring reliability and safety in a wide array of engineering projects.

What is A307?

ASTM A307 is an authoritative standard that defines the chemical and mechanical properties for carbon steel bolts, studs, and threaded rod with a minimum tensile strength of 60,000 PSI. Developed by ASTM International, this proven specification serves as a cornerstone for ensuring the integrity of fasteners used in numerous general-purpose applications across various industries.

Scope & Purpose

This comprehensive standard governs the material composition, manufacturing processes, and mechanical performance of carbon steel fasteners. It specifically covers Grade A bolts, studs, and threaded rod intended for general applications, and Grade B for specific uses like flanged joints in piping systems with cast iron flanges. A307 explicitly excludes specialized fasteners such as machine screws, thread-cutting screws, and mechanical expansion anchors, directing users to other ASTM specifications for those needs.

Who Must Comply?

• • Primary audience: Materials Engineers, Mechanical Engineers, Quality Control Inspectors, Procurement Specialists, and Manufacturing Engineers.
• • Industries affected: Manufacturing, Construction, Oil and Gas, Heavy Machinery, Infrastructure, and any sector utilizing general-purpose steel fasteners.
• • Compliance nature: While often specified in contracts and purchase orders, compliance is typically voluntary unless mandated by project specifications or regulatory bodies.
• • Enforcement: Compliance is typically verified through quality control inspections, material testing reports, and audits conducted by project owners, third-party inspectors, or regulatory agencies.

Key Requirements Overview

Professionals must ensure that fasteners procured and used under A307 meet several core criteria:

• • Material Integrity: The standard mandates specific chemical composition limits for carbon and manganese, along with maximum allowances for phosphorus and sulfur to ensure weldability and mechanical performance.
• • Mechanical Properties: Fasteners must exhibit a minimum tensile strength of 60,000 PSI for Grade A, and a range of 60,000 to 100,000 PSI for Grade B. Hardness requirements are also specified.
• • Manufacturing Processes: Bolts can be produced via hot or cold forging or machining. Heat treatment, including stress relief annealing for certain cold-headed configurations, is addressed.
• • Thread Requirements: Threads can be either rolled or cut, with specific dimensional considerations often referenced in complementary standards.
• • Coating Options: When specified, zinc coatings (hot-dip or mechanically deposited) must adhere to the requirements of related ASTM standards, ensuring corrosion resistance.

Related Standards & References

ASTM A307 is often used in conjunction with other industry-leading standards:

• • ASTM A563: This specification covers the requirements for carbon and alloy steel nuts, ensuring compatibility with A307 bolts and studs.
• • ASME B1.1: This standard defines Unified Screw Threads, providing critical dimensional data and tolerances for the threads on A30