Local heater used in molding of pipe orifice of main steam super pipe and method for heating master pipe blank by using same

The invention relates to a local heater used in molding of a pipe orifice of a main steam super pipe and a method for heating a master pipe blank by using the same. The local heater comprises a combustion head and a fire damper disk, wherein the combustion head consists of an air inlet pipe, a combustible gas inlet pipe, a combustion chamber and the like; the contact surface of the combustion chamber and the master pipe blank of the main steam super pipe is a curved surface; the fire damper disk is provided with a contact type thermocouple, an automatic ignition device and a fire-resistant, heat-insulating and heat-preservation layer; and the contact type thermocouple is in contact with the master pipe blank of the main steam super pipe. During heating, air and combustible gas enter the combustion chamber, the movable fire damper disk is arranged on a supporting rod in the master pipe blank of the main steam super pipe and is in fit with the inner wall of the master pipe through a circular arc surface, and a