Production Process, Performance Characteristics, and Applications of Longitudinal Welded Steel Pipes

First, the Production Process of Longitudinal Welded Steel Pipes.

The production process of longitudinally welded steel pipes primarily includes forming, welding, sizing, and finishing. First, the steel strip is uncoiled and leveled before entering a forming machine for continuous bending to form a tube billet. During the forming process, the edges of the strip are precisely butted together, preparing for subsequent welding. Welding is the core step in the production of longitudinally welded steel pipes. Common welding methods include high-frequency electric resistance welding (ERW), submerged arc welding (SAW), and laser welding. High-frequency electric resistance welding has become the mainstream technology for longitudinally welded steel pipe production due to its high efficiency and low cost. After welding, the tube billet passes through a sizing machine for dimensional calibration to ensure that the diameter and wall thickness meet standards. Finally, finishing processes (such as straightening, cutting, and flaw detection) further enhance the surface quality and mechanical properties of the welded steel pipe.

Second, the Performance Characteristics of Longitudinal Welded Steel Pipes.

1. High Dimensional Accuracy: Longitudinal welded steel pipes utilize a continuous forming process, enabling precise control of diameter and wall thickness, meeting the demands of high-precision applications. For example, in automotive manufacturing, straight seam welded steel pipes are commonly used in drive shafts and chassis components, where their dimensional stability directly impacts vehicle performance.

2. Excellent Mechanical Properties: Through appropriate welding processes and subsequent heat treatment, the tensile strength, yield strength, and elongation of straight seam welded steel pipes can reach or even exceed those of seamless steel pipes. For example, API 5L straight seam welded steel pipes are widely used in oil and gas transportation, and their pressure-bearing capacity and deformation resistance are highly recognized.

3. Excellent Surface Quality: Straight seam welded steel pipes have a smooth surface and flat weld seams, allowing them to be used directly without additional processing. In the construction sector, straight seam welded steel pipes are commonly used in decorative structures and load-bearing frames, and their aesthetics and durability are widely recognized.

4. Low Production Cost: Compared with seamless steel pipes, straight seam welded steel pipes offer significant cost advantages due to their high raw material utilization, short production cycle, and low energy consumption. This makes them a preferred material for large-scale infrastructure construction.

Third, Applications of Straight Seam Welded Steel Pipes.

Straight seam welded steel pipes have an extremely wide range of applications, covering nearly every industrial sector. The following are several typical application scenarios:

1. Construction: Longitudinal welded steel pipe is a primary material for building steel structures, used in beams, columns, and trusses in large buildings such as factories, bridges, and stadiums. Its high strength and lightweight characteristics help reduce construction costs and improve construction efficiency. For example, some venues for the 2025 Hangzhou Asian Games utilized high-strength longitudinal welded steel pipe structures, meeting design requirements while shortening construction schedules.

2. Energy: In the oil and gas transportation sector, longitudinally welded steel pipe is a crucial component of long-distance pipelines. With the development of deep-sea oil and gas fields, demand for corrosion-resistant and high-pressure-resistant longitudinal welded steel pipe continues to grow. Furthermore, longitudinal welded steel pipe is used in cooling systems for nuclear power equipment and support structures for solar panels.

Fourth, Market Prospects for Longitudinal Welded Steel Pipe.

With the global economic recovery and the rise of emerging markets, demand for longitudinal welded steel pipe is steadily growing. According to industry analysis, the global welded steel pipe market is expected to exceed US$150 billion in 2025, with longitudinal welded steel pipe accounting for over 60% of this. The following are the main factors driving market growth:

1. Increased infrastructure investment: Governments around the world have increased their investments in transportation, energy, and municipal infrastructure, driving demand for straight-seam welded steel pipes. For example, China's 14th Five-Year Plan explicitly calls for improving its integrated transportation network, which will directly promote the use of straight-seam welded steel pipes in bridges, tunnels, and rail transit.

2. Expansion of the new energy industry: The rapid development of new energy projects such as wind power and photovoltaics has opened up new market opportunities for straight-seam welded steel pipes. Wind turbine towers and photovoltaic racks are in strong demand for high-strength, corrosion-resistant, straight-seam welded steel pipes.

3. Technological advancements drive upgrades: The application of new materials and processes has further expanded the application scenarios of straight-seam welded steel pipes. For example, the use of duplex stainless steel straight-seam welded steel pipes in chemical equipment has increased year by year, while the introduction of composite materials has enhanced the overall performance of welded steel pipes.

4. Stricter environmental protection requirements: The popularization of green manufacturing and circular economy concepts has prompted companies to pay more attention to product lifecycle management. Due to its recyclability and low environmental impact, straight-seam welded steel pipes play an important role in sustainable development strategies.

Fifth, Development Trends of Longitudinal Welded Steel Pipes

1. High-End: As application scenarios become more complex, market requirements for the performance of longitudinal welded steel pipes are becoming increasingly demanding. For example, deep-sea oil and gas extraction requires welded steel pipes that can withstand extreme environments, while the aerospace industry places even higher standards on material lightweighting and strength.

2. Intelligence: The application of Industry 4.0 technologies will drive the development of intelligent longitudinal welded steel pipe production. By optimizing process parameters through big data analysis and artificial intelligence, product quality and production efficiency can be further improved.

3. Customization: The diverse demands of downstream industries are prompting longitudinal welded steel pipe manufacturers to provide more customized services. For example, the construction industry is experiencing rapid growth in demand for special-shaped welded steel pipes, while the automotive industry prefers to purchase pre-fabricated welded steel pipe components.

4. Internationalization: With the deepening implementation of the Belt and Road Initiative, Chinese longitudinal welded steel pipe manufacturers are accelerating their overseas expansion. Through technology exports and production capacity cooperation, Chinese-made longitudinal welded steel pipes are gaining a wider international market share.

Conclusion

As a cornerstone material of modern industry, the importance of straight-seam welded steel pipe is self-evident. From production processes to performance characteristics, from application areas to market prospects, the development of straight-seam welded steel pipe has always been closely linked to industrial progress. Facing future challenges and opportunities, the straight-seam welded steel pipe industry must continue to innovate, enhance technological capabilities, expand application scenarios, and provide higher-quality material solutions for global industrial development.