Manufacturing Standards for Fully Threaded Studs and Double-End Stud Bolts

2025-12-03 09:32:22

In the fastener industry, distinguishing between standard bolts and high-strength bolts is essential for ensuring the correct application and safety performance. At ASM FASTENER, we specialize in the engineering and manufacturing of fully threaded studs, stud bolts, and high-performance fasteners that meet stringent global standards.
The following provides a clear overview to help customers better identify and understand high-strength fasteners.

1. Visual Identification of Standard vs. High-Strength Bolts

One of the most intuitive methods to differentiate fastener grades is by inspecting the appearance and specifications.

• High-strength bolts are typically paired with extra-wide or heavy-duty washers and nuts.

• The surface finish of high-strength bolts is generally superior due to additional protection processes.

• To prevent a reduction in mechanical strength caused by corrosion, high-strength bolts are commonly treated with galvanizing, nickel plating, passivation, or other corrosion-resistant coatings.

These surface treatments not only enhance durability but also ensure long-term performance in critical applications such as petrochemical plants, offshore platforms, pressure vessels, and heavy machinery.

2. Strength Grade Markings

Another reliable way to verify bolt category is by checking its grade marking:

• High-strength bolts are clearly marked with designations such as Grade 8.8, 10.9, 12.9, or material codes like ASTM A193 B7 / A320 L7.

• Standard bolts may carry lower grades, such as Grade 4.6 or 4.8, indicating lower tensile properties.

At ASM FASTENER, all stud bolts and nuts are produced according to international standards such as ASTM, ASME, ISO, DIN, and are delivered with traceable heat numbers and material certificates (EN 10204 3.1) upon request.

3. Mechanical Performance Testing

To fundamentally confirm the strength level of a bolt, mechanical testing is essential.

Standard low-grade bolts generally exhibit limited performance in tensile strength, shear strength, and yield properties, and are unsuitable for high-load or high-temperature environments.

In contrast, high-strength bolts must meet strict mechanical requirements, including:

• Higher tensile strength

• Higher yield strength

• Better elongation and toughness

• Stability under vibration, dynamic load, and thermal stress

4. Tensile Test — The Most Direct Verification

A commonly used evaluation method is the tensile test.

• Standard bolts tend to fracture easily during tensile testing, indicating lower hardness and insufficient elongation.

• High-strength bolts withstand significantly higher loads without failure, demonstrating superior material quality and heat treatment control.

As an experienced manufacturer with more than 14 years of expertise, ASM FASTENER ensures that all fully threaded studs and double-end stud bolts undergo rigorous inspection—CMM measurement, hardness testing, PMI, tensile testing, and ultrasonic or penetrant examination when required.