ERW tube mill, open the coil and delivery the accumulator with same speed. in the forming and sizing machine, use the HF solid-state welder to welding the steel to the tube. it could saisfy the round, rectangle and square tube. the finished tube could be usded in the building, metallurgy ,transportation etc.. the main characturistic is high speed and effective, save time and power,. feature: high strength and strong rigidity.