VERTICAL PORTABLE LATHE for turning and grinding the security valve tuyere seats installed in the various equipments comprising the Power Station boiler, such as header, superheater, cold reheating and hot reheating, also applicable to security and pressure relief valve installed in all types of industries, acting on the spot, with perfection and easy maneouvrability fastness, ready installation and light weight, which may be installed in all types of security valves and pressure relief valves installed both in the main as well as in the ancillary circuits of Nuclear Power Plants, Power Stations, Petrochemical Plants, Refineries, Cellulose Industries, etc, performing these works in a few minutes.