ERW pipe manufacturing process and application

ERW pipe manufacturing process and application

Resistance welding (ERW Welded Pipe) is used to transport vapor and liquid objects such as oil and natural gas, and can meet various requirements of high and low pressure. Currently, it occupies a pivotal position in the field of transportation pipes in the world.

Electric resistance welded pipe is produced by cold forming a sheet of steel into a cylindrical shape, then passing an electric current between the two edges of the sheet to heat the sheet to a point of force that forces those edges to form a weld. Initially no filler material is used, but a low frequency Alternating current heats the edges. This low frequency process was used from the 20's to the 70's. In 1970, the low frequency process was replaced by the high frequency ERW tube process, resulting in higher quality welds. Over time, it has been found that the welds of low frequency ERW pipes are prone to selective joint corrosion, hook cracks and insufficient joint bonding. Therefore, low frequency ERW is no longer used in the manufacture of 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. ERW tubes are cold formed to a cylindrical shape, not thermoformed. An electric current is used instead of a flame to heat the edges of the strip for welding. A rotating copper disk acts as an electrode that raises the temperature to approximately 2600°F for effective welding. Unlike longitudinal submerged arc welding, ERW typically uses an 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 at 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 welding. Therefore, the structure of the base material changes in a relatively small area around the fusion line (weld center). Use a scraper device to remove molten material inside and outside the weld.

ERW pipe manufacturing process:

This process is characterized by two effects: the skin effect or the concentration of high frequency current at 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 welding. Therefore, the structure of the base material changes in a relatively small area around the fusion line (weld center). Use a scraper device to remove molten material inside and outside the weld.

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

ERW pipe stands for electric resistance welded pipe. According to customer requirements, we can manufacture ERW steel pipes in different sizes and shapes. We have very large production capacity of erw pipes. ERW steel pipes are used in various engineering purposes including fencing, scaffolding, line pipe, etc. ERW steel pipes are available in lengths ranging from a single random to 120 feet depending on the capacity of the rolling mill. ERW pipe has a square or groove for welding, threading, and Victaulic grooving. Finishes can be black or bare, or with a protective coating.

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