A burner tube adapted to pass through an opening in the roof of a coke oven for insertion into a burner nozzle in the sole of a vertical heating flue for the coke oven, the lower portion of said burner tube being insertable into a bore in the burner nozzle such that its outer periphery is in abutment with the inner periphery of the bore and having radially-extending lugs on its outer periphery which rest on the upper surface of the burner nozzle when said lower portion of the burner tube is inserted therein, the burner tube being cylindrical in configuration and formed from alumina of at least 99.9% purity, the lower portion of the burner tube having a length of at least 100 millimeters, and the wall thickness of said burner tube being 6 millimeters or less and uniform throughout its entire length except at said lugs.