Abstract: Disclosed is a machine for flash butt welding of pipes located in the bore of the pipes welded together, a housing (2) whereof is provided with rigidly attached thereto a first supporting disc (3) and a second supporting disc (4) and with a pipe flashing-and-upsetting means (5) which has a carrier (7) and a hydraulic actuator (6) for displacing said means along the housing (2) and also has two pipe clamping means (9, 10) each whereof is provided with a carrier (12 and 13) and self-contained hydraulic actuators (11) imparting axial motion to this clamping means.