It should be noted that the transmission equipment of solid-state high-frequency pipe welding machine is three independent transmission systems, each of which has a related rack installed in a common gear box. Each transmission system is driven by a communication motor. SKF seals are selected for gear box bearings, but imported ones. The rack replacement equipment with hydraulic drive on the operating side is used for roll coupling and quick conversion to a different model. When the solid-state high-frequency pipe welding machine is replaced, the old rolling frame is pulled out by a set of hydraulic equipment and sent to the roller-changing trolley to change the trolley. After the new rolling frame enters the roller-changing direction, the same set of hydraulic equipment pushes it into the stripper to complete rapid roll changing. The trolley of the solid-state high-frequency pipe welding machine has two loading areas, one for storing the old rack and the other for storing the new rack.