“HK-600D” pipe-orifice gas cutter is portable. The machine is used to cut T shape joint accurately which is connected between high pressure vessel and heat-exchange equipment. Pipe intersection welding needs to open core with cutting on the main pipe. The machine is a self-locking mechanism that the torch rises and falls automatically. The self-locking mechanism uses trigonometry principle to make mechanic equipment trace cylinder curved face accurately, which makes torch move as pathway. It is considered to reduce machine weight and take it conveniently in the design. It makes use of infinity revolving gas distributor to make pipeline not twist. The machine can cut circle and bevel. The machine is constituted of control box, torch and self-locking system. Every part is connected with main body rack. With clutch equipment, torch is revolved manually without electric equipment and snapped to cutting point. Control box which is fixed on the top of mechanism is operated and repaired easily.