Large-diameter seamless steel pipes (Ф4061500mm x 6.4270.0mm) are very common in modern industry and are widely used in general fluid delivery pipes, oil and gas pipelines, structural pipes, pressure vessel pipes, high-pressure boiler pipes and military pipes. The standard for large-diameter seamless steel pipes is ASTM A252. The materials of these steel pipes mainly include high-quality carbon structural steel, alloy structural steel, stainless steel and special alloys. Although China's small and medium-diameter seamless steel pipe production equipment has developed rapidly, the production of large-diameter seamless steel pipes is still lagging behind. At present, China has more than 150 seamless steel pipe production plants, with about 289 sets of various seamless steel pipe units (including 17 sets under construction), of which only about 11 sets of main equipment (including those under construction) can produce large-diameter seamless steel pipes. Despite this, it still cannot meet the market's growing demand for large-diameter seamless steel pipes.
Application fields of large-diameter seamless steel pipes
1. General fluid delivery pipes
Large-diameter seamless steel pipes are often used to transport liquids and gases such as water, oil, and natural gas. Their excellent strength and corrosion resistance ensure the stability and safety of the transportation system, especially in long-distance transportation, which can significantly reduce leakage and loss.
2. Oil and gas pipelines
Oil and gas pipelines have extremely high requirements for steel pipes, which must have good pressure resistance and corrosion resistance. Large-diameter seamless steel pipes are widely used in oil and gas pipelines because of their excellent mechanical properties and corrosion resistance.
3. Structural pipes
In buildings and engineering structures, large-diameter seamless steel pipes are often used to manufacture structural frames and support systems due to their high strength and good toughness. Their excellent performance makes them an ideal choice for large structures such as high-rise buildings and long-span bridges.
4. Pipes for pressure vessels
Pressure vessels are used to store and transport various liquids and gases, and have extremely high requirements for materials. Large-diameter seamless steel pipes are widely used in the manufacture of various pressure vessels due to their excellent pressure resistance and corrosion resistance, ensuring their safety and reliability.
5. Pipes for high-pressure boilers
High-pressure boilers operate under high temperature and high pressure conditions, and the performance requirements for pipeline materials are very demanding. Large-diameter seamless steel pipes have high-temperature strength and good oxidation resistance, and are an ideal choice for high-pressure boilers, ensuring the efficient and safe operation of boilers.
6. Military pipes
In the national defense industry, large-diameter seamless steel pipes are widely used in the manufacture of various military equipment and facilities, such as missile launch tubes and submarine pipelines, due to their excellent mechanical properties and reliability, ensuring the performance and safety of national defense equipment.
Challenges and Solutions for Large Diameter Seamless Steel Pipe Production
Although large diameter seamless steel pipes are widely used in industry, their production faces many challenges. China's domestic production capacity for large diameter seamless steel pipes is insufficient, and the maximum outer diameter specifications of hot-rolled seamless steel pipes are also limited. In order to solve this problem, people try to achieve the production of larger diameter seamless steel pipes through hot expansion process. Compared with hot-rolled seamless steel pipes with high production costs and expensive equipment, the hot expansion process has the advantages of simple production process, stable quality, economical and practical, low cost and high production efficiency. As an extension of the main line of smelting and pipe rolling, the hot-expanded seamless steel pipe fills the gap in the specifications of large diameter seamless steel pipes in China and meets the special needs of users.
Importance of welding preparation work
In the application process of large-diameter seamless steel pipes, welding preparation work is particularly important. The selection and use of welding rods directly affect the chemical composition and performance of the weld. The selection of suitable welding rods requires comprehensive consideration of the performance requirements of the weld metal, the shape, rigidity and weld position of the welding rod, the crack resistance of the weld metal, the operation process, the equipment and construction conditions, and the economic rationality. Sometimes it is necessary to verify through experiments to finally determine the most suitable welding rod.
Environmental friendliness and safety
As developed countries around the world have adopted a large number of welded pipe seamless processes in fluid pipes and boiler pipes, China has gradually formed a situation where hot-rolled welded pipes gradually replace seamless pipes. The difference between seamless steel pipes and large-diameter seamless steel pipes can be seen from several aspects. First, welded pipes are generally fixed in length, with common lengths of 6 meters, 9 meters or 12 meters, while seamless steel pipes are very rare in length because the factory price increase for fixed lengths is very high. Secondly, you can see from the cross-section of the pipe head that if there is rust, wipe it clean and you will find the welding area. Finally, the welding area is more obvious after pickling.
Plastic coating technology for large-diameter seamless steel pipes
The quality of surface pretreatment of large-diameter plastic-coated steel pipes indirectly affects the adhesion of the coating. Steel pipes with surface pretreatment should be plastic-coated within 6 hours, and should be re-treated if they exceed the time limit. Large-diameter seamless steel pipes have large elastic deformation, and improper operation during construction can easily cause large vertical deformation or even instability of the steel pipe, seriously affecting its use function. Plastic-coated steel pipes can be coated with plastic coatings such as polyvinyl chloride, polyethylene, and epoxy resin as needed. They have the advantages of good adhesion, strong corrosion resistance, wear resistance, impact resistance, and smooth pipe surface, which improves the transportation efficiency and flow rate and reduces the transportation pressure loss.
Future Outlook
Although the production and practice of hot-expanded steel pipes have been widely used, further research and improvement are still needed in terms of production technology improvement and control of the accuracy of various parameters of hot-expanded steel pipes. It is hoped that Chinese steel pipe companies will strengthen cooperation, jointly tackle key problems and improve the production standards of hot-expanded steel pipes to further promote the development of the steel pipe industry.
In short, large-diameter seamless steel pipes play an important role in industrial production and infrastructure construction due to their excellent performance and wide application prospects. With the continuous advancement of production technology and the continuous increase in market demand, large-diameter seamless steel pipes will usher in a broader development space.
English
Español
بالعربية
Phone : 
Whatsapp : 
Email : 
