ASTM A307 Bolts

1. What is ASTM A307?

ASTM is an international standards organization that develops and publishes technical standards for structural bolts, alloy steel, and heat treatment. ASTM A307 and A307M are standards for carbon steel bolts with a minimum tensile strength of 60 ksi. ASTM A307 bolts are available in diameters ranging from 5/8” to 4” (M16 – M80).

 

2. Key Features of ASTM A307 Bolts

Classification by Strength Grade

ASTM A307 bolts are manufactured and classified into three strength grades: A, B, and C. All are made from carbon steel with a minimum tensile strength of 60 ksi. However, Grade C has been replaced by ASTM F1554 - 36.

• Grade A: Hex head bolts with a minimum tensile strength of 60 ksi, used for general applications.
• Grade B: High-strength hex bolts with a tensile strength of 60 - 100 ksi, commonly used for flange connections in piping systems.
• Grade C: Replaced by ASTM F1554 - 36.

Thread Types

ASTM A307 bolts follow American thread standards, including:

• UNC (Unified National Coarse): The most commonly used thread type in the U.S., suitable for low-strength applications requiring easy assembly and disassembly, such as low-carbon steel materials.
• UNF (Unified National Fine): Fine threads, ideal for high-strength applications or joints with thin walls and short engagement lengths.
• 8UN (8 Threads Per Inch): A variation of UNC threads, where the number of threads per inch remains 8 across all diameters.

 

ASTM A307 bolts are manufactured in diameters ranging from ¼” to 4” following ASME B18.2.1 standards for heavy hex bolts and standard hex bolts.

 

Surface Treatments

ASTM A307 bolts typically come with hot-dip galvanized or plain black finishes. However, we also offer other coatings upon request, including:

• Electro-galvanized (white-blue zinc, gray zinc, yellow zinc – 7 colors)
• Geomet coating
• Dacromet coating
• Black oxide treatment

3. Applications of ASTM A307 Bolts

As a standard for carbon steel structural bolts, ASTM A307 bolts are widely used across various industries, including:

• Construction and mechanical engineering projects
• Bridge, road, and marine structures such as shipbuilding and dock construction
• Roof installations in factory construction and steel structures
• Flange connections in petrochemical and oil refining industries

4. Pricing of ASTM A307 Bolts

The price of ASTM A307 bolts and threaded rods depends on several factors:

• Type: Each type of ASTM A307 bolt has a different price based on shape and manufacturing process. Example: Heavy hex bolts cost more than standard hex bolts.

• Strength Grade: Higher strength grades are priced higher. Example: Grade B bolts are more expensive than Grade A.

• Size: Larger diameter and longer bolts are priced higher. Example: M42 bolts cost more than M39, and M20x120 bolts cost more than M20x100.

• Surface Treatment: Different coatings have different costs. Example: Hot-dip galvanizing is more expensive than electro-galvanizing due to its superior corrosion resistance.

5. Why Choose ASTM A307 Bolts from Quang Thai?

Quang Thai is proud to be a leading manufacturer and distributor of ASTM A307 bolts in southern Vietnam. As one of the top suppliers of bolts and fastening materials, we provide high-quality products at competitive prices. Our commitment to quality ensures reliability and durability for all our customers.

For the best ASTM A307 bolts, contact us at +84 933 220 468. Quang Thai is honored to serve you!