Electric Resistance Welded (ERW) Pipe Manufacturing Process

Press Release : October 19, 2020
Electric Resistance Welded (ERW) Pipe Manufacturing Process

Electric resistance welding (ERW) is used to transport oil, natural gas and other vapor and liquid objects, which can meet various requirements of high and low pressure, and currently occupies a pivotal position in the field of transportation pipes in the world.

The electric resistance welding (ERW) pipe is manufactured by cold forming a piece of steel plate into a cylindrical shape, and then passing an electric current between the two edges of the steel plate to heat the steel plate to a point of force, forcing these edges to form a weld that was not initially used Fill the material, but use low frequency alternating current to heat the edges. This low frequency process has been used from the 1920s to the 1970s. In 1970, the low frequency process was replaced by the high frequency ERW pipe process, which produced higher quality welds. Over time, it has been found that the welds of low-frequency ERW pipes are susceptible to selective joint corrosion, hook cracks and insufficient joint bonding. Therefore, low-frequency ERW is no longer used to make pipes. High-frequency processes are still used to make pipes for new pipeline construction.

Resistance welding can be divided into resistance welding and induction welding. The ERW tube is cold formed into a cylindrical shape rather than hot formed. Use electric current instead of flame to heat the edges of the strip for welding. The rotating copper disk is used as an electrode, which can raise the temperature to about 2600┬░F for effective welding. Unlike longitudinal submerged arc welding, ERW usually uses alternating current with a frequency of 100 to 800 kHz, or 100.000 to 800.000 cycles per second.

This process is characterized by two effects: the skin effect or the concentration of high-frequency current on the surface, and the proximity effect when the high-frequency is concentrated on two adjacent parallel inner edges in the welding wedge before the welding point. These effects minimize the heat released during the welding process. Therefore, the structure of the basic material changes in a relatively small area around the fusion line, the center of the weld. Use a scraping device to remove the molten material on the inside and outside of the weld.

ERW Pipe Manufacturing Process:

Electric Resistance Welded (ERW) Pipe Manufacturing Process 1

This process is characterized by two effects: the skin effect or the concentration of high-frequency current on the surface, and the proximity effect when the high-frequency is concentrated on two adjacent parallel inner edges in the welding wedge before the welding point. These effects minimize the heat released during the welding process. Therefore, the structure of the basic material changes in a relatively small area around the fusion line, the center of the weld. Use a scraping device to remove the molten material on the inside and outside of the weld.

In the production of ERW steel pipes, only high-quality, continuous casting, fully sedated, controlled rolling, fine-grained low carbon steel is used. High-performance ERW steel pipes and tubes have high strength, corrosion resistance, high deformability, high strength and high toughness. Permanent Steel Manufacturing Co.,Ltd is one of the leading manufacturers and suppliers of ERW tubes in China. We are also one of the largest exporters of ERW pipes in China.

ERW pipe stands for resistance welded pipe. According to customer requirements, we can manufacture ERW steel pipes of different sizes and shapes. We have very large erw pipe production capacity. ERW steel pipes are used for various engineering purposes, including fences, scaffolding, line pipes, etc. The length of the ERW pipe varies from a single random to 120 feet, depending on the capacity of the rolling mill. ERW pipes have square heads or grooves for welding, threaded connections and Victaulic slotting. The surface treatment can be black or bare, or with a protective coating.

Notes to editors

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