Ascension pipe elbow lid for coke ovens

An improved ascension pipe elbow for coke ovens wherein the elbow has an angularly disposed circular shoulder in an upper portion thereof defining a vent opening in said elbow, the improvement consisting of a lid, means on the elbow hinging the lid thereto for arcuate movement toward and away from said vent opening, an inverted dome-shaped circular baffle and means attaching said baffle to said lid, said baffle positioned for location through said vent opening and substantially within said ascension elbow when said lid is closed, an insulating gasket of refractory fibrous material positioned between said lid and said inverted dome-shaped baffle with the peripheral edge of said gasket normally engaged between said lid and said circular shoulder on the ascension elbow surrounding the vent opening therein so as to normally seal the same.