20. What is high-frequency welded square pipe? Are there any other names?

High-frequency welded round tubes are round tubes made by welding metal materials (mainly steel plates) together using the resistive thermal effect of high-frequency currents, and then formed into square tubes. In addition, there are high-frequency welded round pipes that become square pipes after "pushing squares". "Pushing the square" is the power of the fixed diameter to push the steel pipe to be corrected into a square pipe.
High-frequency welded square pipes are generally known as square pipes, square pipes, rectangular pipes, etc. It is named because its cross-section is square.