How is pressure applied in ERW?

• A. Through electrodes and is usually supplied by pneumatic or hydraulic cylinders.
• B. By manual hammering.
• C. By gravitational force.
• D. Using magnetic clamps.

Answer: (A)

In ERW, the seam is forged together while current passes through the ends, and the pressure required to form the weld is applied by the electrode system. The welding head clamps the tube ends with electrodes and uses pneumatic or hydraulic cylinders to deliver a controlled clamping force. This pressure, in combination with the electrical current, brings the metal ends into intimate contact and produces the weld across the seam. The pressurized electrode action ensures consistent contact, helps drive the forge weld, and keeps the ends properly aligned during heating. Manual hammering, gravity, or magnetic clamps do not provide the controlled, direct pressure needed for ERW welding.