PURPOSE: To achieve the reduction of the diameter as well as the improvement of the operability of a burner, by a method wherein a hydrogen pipeline, at the tip end of a grip formed by providing an oxygen pipeline in the hydrogen pipeline concentrically, is sealed and a reverse flow preventing wall is provided while an internal mixing chamber, mixing hydrogen gas in the hydrogen pipeline with oxygen in the oxygen pipeline, is provided at the tip end opening of the hydrogen pipeline, detoured around the reverse flow preventing wall.

CONSTITUTION: An oxygen pipeline 20 is positioned on and held by a reverse flow preventing wall 11 to hold it concentrically with a good accuracy without generating the deviation of the center or the like. According to this constitution, uniform and stabilized internal mixing flow may be obtained in an internal mixing chamber 4. The nozzle unit 21 of the oxygen pipeline, positioned in the internal mixing chamber, is positioned at the tip end opening of the detoured hydrogen pipeline 5, whereby more uniform internal mixing may be effected. The reverse flow preventing wall 11 is interposed between the mixing chamber 4 and the grip 3 in the hydrogen pipeline 1 in the grip 3, therefore, the possibility of backfire of the flame stream in the mixing chamber 4 up to the grip 3 at the upstream side thereof may be eliminated and the property of safety of the burner may be improved remarkably. Further, the tip end of a pipeline 7, forming the mixing chamber 4, is extended whereby an apparent focal length between the tip end of the burner and a welded position may be shortened and the operability of the burner may be improved much more.