Precautions for construction of high-strength bolts

High strength bolts are widely used in various engineering fields due to their high load-bearing capacity, good seismic performance, and easy construction. However, the construction of high-strength bolts is a complex process that requires strict adherence to construction techniques and quality control measures. This article summarizes the main points and precautions for high-strength bolt construction based on relevant standards and the author's work experience.

1. Performance guarantee measures

The performance assurance measures for high-strength bolts mainly include material selection, manufacturing process control, and quality testing. In Europe and America, high-strength bolts are usually made of alloy steel with a minimum yield strength of 830 MPa. The manufacturing process includes cold heading, thread processing, heat treatment, and surface treatment. During the manufacturing process, material composition, heat treatment temperature and time, and thread rolling process parameters should be strictly controlled to ensure the mechanical properties and thread accuracy of bolts. Quality testing includes chemical composition analysis, mechanical performance testing, and non-destructive testing.

2. Construction process

The construction process of high-strength bolts mainly includes pre tension and installation. In Europe and America, high-strength bolts are usually pre tensioned using hydraulic tension equipment. The pre tension force value should be calculated based on design requirements and the mechanical properties of the bolt. During the pre tensioning process, the bolts should be tightened in a cross pattern to ensure uniform distribution of force. The pre tension force value should be verified through methods such as ultrasonic testing. After the pre tension is completed, the installation should be carried out according to the specified torque or angle, and thread lubricant should be used according to the manufacturer's instructions.

3. Construction quality assurance measures

The construction quality assurance measures for high-strength bolts mainly include construction environment control, bolt connection inspection, and construction process document recording. The construction environment should be dry and clean to prevent contamination of bolts and nuts. Bolt connection inspection should include visual inspection, torque or angle verification, and non-destructive testing. The construction process document records should include records of pre tension force values, torque or angle records, thread lubricant usage records, and inspection results records.

4. Precautions

During the construction process of high-strength bolts, attention should be paid to the following aspects:

1. Select appropriate equipment and tools to ensure construction quality;

2. During the pre tension and installation process, attention should be evenly distributed to prevent excessive pre tension and excessive torque;

During the construction process, the amount and quality of thread lubricant should be strictly controlled to avoid excessive or insufficient use;

During the construction process, construction documents should be recorded and summarized in a timely manner for future reference and analysis.

The construction related standards for high-strength bolts mainly include ASTM standards and ISO standards. For example, ASTM A325 and ASTM A490 respectively specify the materials, dimensions, manufacturing processes, and quality requirements for high-strength bolts; ISO 898-1 specifies the mechanical performance requirements and test methods for high-strength bolts. During the construction process, operations should be strictly carried out in accordance with relevant standards to ensure construction quality and safety.