Positioning clamp for heating and ventilation pipe welding

The utility model relates to the technical field of clamps, and discloses a positioning clamp for heating and ventilation pipe welding, which structurally comprises a supporting frame, supporting seats are welded on two sides of the upper end of the supporting frame, a fixing ring is fixedly mounted at the front end of each supporting seat, a rack is movably mounted in an inner cavity of each fixing ring, and a pressing plate is fixedly mounted on the rear side of the upper end of each rack. By means of the supporting frame, the fixing ring, the collecting box, the transmission rod, the pull rope and the spring, when the heating and ventilation pipe is positioned, a gear on the transmission rod can drive a rack to move downwards, a pressing plate on the rack is matched with a supporting base to press and limit the heating and ventilation pipe, the situation of welding deviation caused by shaking is avoided, and the welding quality is improved. The trouble of manually limiting the heating and ventilation pipe