What Does ERW Steel Pipe Meaning
2025-03-06
What Does ERW Steel Pipe Meaning
1. What is ERW Steel Pipe?
ERW steel pipe, or Electric Resistance Welded pipe, is a type of straight seam welded pipe commonly used for transporting liquids and gases such as oil and natural gas. It is designed to withstand both high and low-pressure applications, making it an essential component in pipeline systems worldwide.
Welded pipes are produced by joining steel plates and can be categorized into different types, including high-frequency electric resistance welded (ERW) pipes, longitudinal submerged arc welded (LSAW) pipes, and spiral welded pipes. In electrical engineering, "SC" pipes are typically thicker and used for water, gas, or electrical conduit applications, whereas "T" pipes, which are thinner, serve primarily as electrical conduits.
Unlike conventional welded pipes, ERW pipes are manufactured using high-frequency resistance welding, where the edges of the steel strip are heated and fused without the need for additional filler material. This process results in a stronger and more uniform weld, enhancing the pipe’s mechanical performance.
Electric resistance welding is widely recognized for its high efficiency, cost-effectiveness, and ease of automation. Due to these advantages, ERW pipes play a vital role across various industries, including aerospace, energy, electronics, automotive, and construction.
2. ERW Pipes and Tube Manufacturing Process
The manufacturing process of Electric Resistance Welded (ERW) pipes involves cold-forming a flat steel sheet into a cylindrical shape. Once shaped, an electric current is applied to the edges, heating the material until it fuses together, forming a strong bond without requiring additional welding filler material.
There are several ERW manufacturing techniques, but the two primary methods are:
High-Frequency Welding Process
Rotary Contact Wheel Welding Process
(1). High-Frequency Welding Process
Originally, ERW pipes were manufactured using a low-frequency A.C. current to heat the edges. However, this method, used from the 1920s to the 1970s, was phased out due to issues like seam corrosion, hook cracks, and poor seam bonding. The introduction of the high-frequency ERW process significantly improved weld quality and remains the industry standard today.
The high-frequency ERW process is further divided into:
High-Frequency Induction Welding (HFIW): In this process, an electromagnetic coil transmits the weld current to the steel strip without direct contact. Magnetic fields induce the electrical current, ensuring uniform heating of the material. This method minimizes contact marks and simplifies setup when changing pipe sizes.
High-Frequency Contact Welding (HFCW): Here, the weld current is directly applied through contacts that glide along the steel strip. This approach is more electrically efficient than induction welding, making it particularly suitable for producing large-diameter pipes with thick walls.
(2). Rotary Contact Wheel Welding Process
In this method, electrical current is applied through a rotating contact wheel at the weld point, which also exerts the necessary forging pressure for welding. The system operates using three types of power supplies—AC, DC, and square wave—transmitting current via brush assemblies that engage slip rings attached to the rotating shaft.
Rotary contact welding is advantageous for applications where an internal impeder cannot be used, such as in the production of small-diameter refrigeration tubes or tubes that require internal coating immediately after welding.
