High-frequency Electric Resistance Welding (ERW), Straight Seam Welding, And Spiral Welding

In the manufacturing process of welded steel pipes, welding process is a crucial link. According to different welding methods, welding technology can be divided into several types. The three most common welding methods are high-frequency resistance welding (ERW), straight seam welding and spiral welding. Each welding method has its specific application scenarios and advantages in steel pipe manufacturing. The following will analyze in detail the application of these three welding processes in welded steel pipes and their professional characteristics.

                                                  

1. High-frequency resistance welding (ERW)

High-frequency resistance welding (ERW) is one of the most commonly used welding methods in welded steel pipes, especially suitable for the production of small and medium-diameter steel pipes. The principle is to heat the edge of the steel pipe to the melting temperature, and then weld the two ends of the steel pipe together under the action of high-frequency current and external pressure.

Key process:

• Heating method: Use high-frequency current to heat the edge of the steel pipe so that the welding edge of the pipe is partially melted. The current frequency is usually between tens to hundreds of kilohertz and has a strong heating capacity.

• Welding method: High-frequency resistance welding realizes welding through the principle of resistance heating, and uses contact resistance and the heat generated by the current to weld the joint area of the pipe.

• Welded joint: The welded joint is usually a straight seam joint. After welding, the weld will undergo post-processing processes such as shaping, cooling, and deburring.

  
  

2. Straight seam welding

Straight seam welding is another common welding method for welding steel pipes, usually carried out by arc welding, gas welding, CO2 shielded welding, etc. The principle is to butt the two ends of the pipe and weld the two ends into a straight joint with the help of an external heat source and filler metal.

Key process:

• Heating method: Welding is carried out by arc or shielding gas. Arc welding melts the metal through the high temperature of the arc, and at the same time forms a protective atmosphere in the welding area to prevent oxidation.

• Welded joint: The welded joint is a straight seam joint, and it is usually necessary to weld the two ends of the pipe together through a welding process to ensure a good combination of the weld and the parent material.

  
  

3. Spiral welding

Spiral welding is a special type of straight seam welding technology. Its main feature is that a spiral welding path is used during the welding process, and the welded joints are distributed in a spiral shape. Spiral welding is suitable for the production of large-diameter (usually diameter greater than 300mm) and thick-walled steel pipes.

Key processes:

• Welding path: The key feature of spiral welding is that the weld seam of the pipe is carried out in a spiral manner along the circumference of the steel pipe, and the welded joints are usually distributed in a spiral shape.

• Welding method: Welding is carried out by welding methods such as submerged arc welding (SAW) and CO2 gas shielded welding (GMAW) to ensure the high quality of the weld.

• Control method: During spiral welding, the control of parameters such as welding speed, welding current, and welding voltage is relatively strict, and it is necessary to ensure uniform heat input during welding.

  
  

In the production process of welded steel pipes, high-frequency resistance welding (ERW), straight seam welding, and spiral welding each have different scopes of application and advantages:

• High-frequency resistance welding (ERW): Suitable for small and medium-diameter pipes, fast production speed, suitable for mass production, mainly used in fluid transportation, building structures and other fields.

• Straight seam welding: suitable for medium and large diameter and thick-walled steel pipes, with high welding quality and pressure bearing capacity, widely used in oil, natural gas transportation, large structures and other fields.

• Spiral welding: suitable for large diameter and thick-walled pipelines, often used in long-distance pipelines, oil and natural gas transportation and other fields, and can withstand large internal and external pressures.

The characteristics and application scope of these three welding processes determine their wide application in different fields, and also provide diversified solutions for welded steel pipes in structural bearing, fluid transportation and other fields.