As a key material in modern bridge construction, the performance and quality of straight seam welded steel pipes for bridges directly affect the safety, durability, and economy of bridges. With the rapid development of my country's transportation infrastructure construction, the application scope of straight seam welded steel pipes for bridges has been continuously expanded, and the technical requirements have also been increasing.
First, the characteristics and advantages of
straight seam welded steel pipes for bridges
Straight seam welded steel pipes for bridges have significant advantages over traditional welded steel pipes.
1. Its weld is straight, the welding process is easier to control, and the weld quality is more stable.
2. The geometric dimensions of straight seam welded steel pipes are highly accurate and the wall thickness is uniform, which can meet the strict requirements of bridge structures for dimensional accuracy.
3. Straight seam welded steel pipes adopt advanced welding technology, with high weld strength and good fatigue resistance, and are particularly suitable for bearing dynamic loads of bridge structures. From the perspective of material properties, straight seam welded steel pipes for bridges usually use low-alloy high-strength steels, such as Q345qD, Q370qE, and other special bridge steels. These steels have good welding performance, low-temperature toughness, and fatigue resistance, and can adapt to the use requirements under various complex environmental conditions. In addition, the inner and outer surfaces of the straight seam welded steel pipe have been specially treated and have excellent anti-corrosion properties, which greatly extend the service life of the bridge.
Second, the production process of straight seam welded steel pipes for bridges
The production of modern straight seam welded steel pipes for bridges adopts an advanced JCOE forming process, which mainly includes the following key processes:
1. Steel plate pretreatment: The steel plate is pretreated by leveling, planning, and other pretreatments to ensure that the edge quality of the steel plate meets the welding requirements. The flatness and edge straightness of the steel plate must be strictly controlled during the pretreatment process.
2. Forming process: The multi-step progressive JCO forming process is adopted to gradually bend the flat plate into a tube through multiple pressing and forming. This process requires precise control of the forming parameters to ensure the geometric dimensional accuracy of the tube blank.
3. Welding process: The multi-wire submerged arc welding process is used for internal and external welding. Internal welding usually uses 4-wire submerged arc welding, and external welding uses 5-wire submerged arc welding. Multi-wire welding can significantly improve welding efficiency and weld quality. During the welding process, the welding parameters must be strictly controlled to ensure the mechanical properties of the weld.
4. Diameter expansion process: The welded steel pipe is shaped by mechanical diameter expansion or hydraulic diameter expansion to eliminate welding stress and improve dimensional accuracy and roundness. The diameter expansion amount is usually controlled within the range of 0.8%-1.2%.
5. Heat treatment process: The welded steel pipe is subjected to overall heat treatment to eliminate welding residual stress and improve material structure and performance. The heat treatment process should be optimized according to the type of steel and wall thickness.
6. Nondestructive Testing: A variety of detection methods such as ultrasound and X-ray are used to conduct comprehensive inspection of the weld to ensure that the weld quality meets the standard requirements.
Third, the key points of quality control of straight seam welded steel pipes for bridges
To ensure the quality of straight seam welded steel pipes for bridges, the following key indicators need to be focused on:
1. Dimensional accuracy control: including outer diameter deviation, wall thickness deviation, ovality, straightness, etc. These indicators directly affect the quality of the pipe joint connection and the overall linear shape of the bridge.
2. Mechanical property control: especially indicators such as yield strength, tensile strength, elongation, and impact toughness. These performance indicators must meet the requirements of bridge design specifications.
3. Welding quality control: The appearance of the weld should be flat and smooth, without defects such as cracks, unfused, slag inclusions, etc. The mechanical properties of the weld should be equivalent to those of the parent material.
4. Anti-corrosion performance control: including surface treatment quality, coating adhesion, etc. Good anti-corrosion performance is the key to ensuring the long-term durability of the bridge.
5. Residual stress control: Control welding residual stress through reasonable process design to avoid early failure caused by stress concentration.
Fourth, the application of bridge straight seam welded steel pipes in bridge structures
Bridge straight seam welded steel pipes are widely used in various bridge structures, mainly including the following forms:
1. Steel tube concrete arch bridge: The straight seam welded steel pipe is used as the main load-bearing member of the arch rib, and the internal concrete is filled to form a composite structure. This structural form gives full play to the tensile properties of steel and the compressive properties of concrete and has the advantages of large spanning capacity and beautiful appearance. For example, the Chongqing Chaotianmen Yangtze River Bridge uses a large number of straight seam welded steel pipes as arch rib components.
2. Steel tube truss bridge: straight seam welded steel pipes are used as truss components, and a spatial force system is formed through node connections. This structural form has clear force and high material utilization and is suitable for large-span bridges.
3. Pier structure: straight seam welded steel pipes can be used as components of bridge piers, especially in high piers and curved piers. Steel tube piers have the characteristics of convenient construction and flexible shape.
4. Temporary support structure: During the construction of bridges, straight seam welded steel pipes are often used as components of temporary support systems. They are easy to install and disassemble and can be reused.
Fifth, the development trend of straight seam welded steel pipes for bridges
With the advancement of bridge construction technology, straight seam welded steel pipes for bridges are developing in the following directions:
1. Application of high-strength materials: Use higher-strength steel, such as Q420q, Q460q, and other high-strength bridge steels to reduce the deadweight of the structure and improve the spanning capacity.
2. Large diameter and thick wall: In order to meet the needs of large-span bridges, straight seam welded steel pipes are developing towards larger diameters and thicker walls. At present, China can produce large straight seam welded steel pipes with a diameter of more than 1.5 meters and a wall thickness of more than 50 mm.
3. Intelligent manufacturing: Introduce intelligent manufacturing technology to realize the digitization, networking, and intelligence of the production process, and improve product quality stability and production efficiency.
Sixth, Conclusion
As an important material for modern bridge construction, the technological progress of straight seam welded steel pipes for bridges has directly promoted the development of bridge engineering. With the continuous improvement of manufacturing technology and the continuous improvement of quality control level, straight seam welded steel pipes for bridges will surely play a key role in more large and complex bridge projects. In the future, with the research and development and application of new materials and new processes, the performance of straight seam welded steel pipes for bridges will be further improved, making greater contributions to my country's bridge construction.
Threeway Steel is known as a professional supplier engaged in manufacturing and distributing a wide range of steel pipe, and our headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
