ERW steel pipe, or "Electrical Resistance Welded Pipe", refers to a steel pipe produced by resistance welding technology, with the weld parallel to the pipe body. This type of steel pipe is formed by hot-rolled coils through a forming machine, and the edge of the tube is heated to a molten state by the skin effect and proximity effect of high-frequency current, and then pressure welding is performed under the action of extrusion rollers to form a weld. This weld is formed by melting the steel strip parent material, which ensures the reliability of mechanical strength. Therefore, ERW welded pipes are widely used in various projects, especially in oil and gas transportation, structural engineering and construction industries.
Definition and production process of ERW pipe
ERW steel pipe is a process that achieves welding by heating the edge of the steel strip with high-frequency current. During the production process, the steel strip or steel plate is first rolled into a tube, and then the edge is heated to a molten state by the skin effect of high-frequency current, and finally a strong weld is formed under extrusion. This welding process has high efficiency, low cost and good automation production potential, so ERW welded pipes occupy a large share of the global welded steel pipe production. Data shows that the output of ERW welded pipes accounts for about 80% of the total global output of welded steel pipes, showing its importance in the field of welded steel pipes. RW welded pipe production lines can produce high-frequency resistance straight seam welded pipes, square pipes, rectangular pipes, steel sheet piles and other products.
ERW pipe steel pipe standards
American Society for Testing and Materials: ASTM A53 B, ASTM A178, ASTM A252 GR.2, A500, ASTM A513
API:
API 5L X42/46/52/56/60/70
EN 10204/10217 S235JR, S275JR, S355, S355JR, S355J2H
Outer diameter: 1/2" -24" (21.3mm-610mm)
Wall thickness: 1.65mm-20mm
What are the characteristics and advantages of ERW steel pipes?
The weld of ERW steel pipe is formed by high-frequency resistance welding technology. Unlike traditional welded pipe welding process, its weld quality is more reliable and its mechanical strength is also better. Its biggest feature is its longitudinal straight seam welding process, which enables it to withstand the pressure from the inside of the pipe well. Therefore, it has been widely used in the transportation of gases and liquids such as oil, natural gas, and chemicals.
In addition, ERW welded pipe also has a high-efficiency production process. Since resistance welding technology does not require additional welding materials, the welding process can be completed efficiently through automated equipment, and the production speed is extremely fast. Compared with other welding processes, such as submerged arc welding, ERW welding has the advantages of saving materials, low production cost, and stable process. These characteristics make ERW welded pipe an important part of the global transportation pipeline field, and it performs well in meeting high-pressure and low-pressure transportation requirements.
Where is ERW pipe used?
ERW straight seam welded pipe is mainly used in water supply projects, petrochemical industry, chemical industry, power industry, agricultural irrigation and urban construction.
(1) For liquid transportation: water supply and drainage.
(2) For gas transportation: coal gas, steam, liquefied petroleum gas.
(3) Structural use: used as piling pipes, bridges; docks, roads, building structures and other pipelines.
Development and application of ERW welded pipes in China
Although the production of ERW welded pipes in China is relatively mature, it still faces the problem of product structural contradictions. Especially in the field of high-end products, compared with developed countries abroad, domestic products still need to be improved in terms of process technology and precision control. Japan and advanced European countries have made a lot of improvements in the production of ERW welded pipes, and their pipe making processes are moving towards product differentiation and process specialization.
Domestic small-diameter ERW welded pipes are mainly used in automobiles, machinery, construction and other fields, but because the manufacturing process remains at the traditional level, the product added value is low. In contrast, medium-diameter ERW welded pipes are mainly used in special environments such as large-scale engineering structures and oil and gas transportation, which puts forward higher requirements for manufacturing processes, including raw material technology, production process control, and improvement of inspection and testing methods.
Process technology and development direction of ERW welded pipes
ERW welded pipe technology continues to develop with the changes in market demand, and product positioning is gradually extending to high precision, high strength and energy saving and consumption reduction. The automation level of production lines is constantly improving, and product quality and technical level are gradually approaching international standards. In major projects such as machinery, energy, petroleum, and chemical industry, ERW welded pipes have become an indispensable and important material due to their superior performance and high cost performance.
Conclusion
The application of ERW welded pipes is mainly concentrated in the fields of small and medium-caliber structural pipes, oil casing pipe, pipeline pipes, and boiler pipes. Driven by market demand, these products are continuously refined and classified with the advancement of production technology. Its wide range of applications, especially in mechanical and structural pipes, occupies a considerable proportion and maintains a growth momentum. Although the proportion of special pipes is relatively stable, it also plays an irreplaceable role in some key applications.