Patent ID: 7240673

Claim:
A flange useful for optical flame observation in a gas turbine, the flange comprising: at least one pane; at least one bore for optical observation, in which at least one bore the at least one pane is positioned for separating a flame-side space from an outside space, the flame-side space for being in substantially direct communication with a combustion chamber in which at least one flame that is to be monitored is located and from which the at least one flame can be observed; said at least one pane comprising two panes which delimit a sealed intermediate space in the at least one bore, the two panes arranged spaced apart from one another and one behind the other with respect to an optical axis; means for dehumidifying the sealed intermediate space; wherein: said two panes include an observation-side pane configured and arranged to be inserted, exchanged, removed, or combinations thereof, from the observation-side end of the flange; said two panes include a flame-side pane configured and arranged to be inserted, exchanged, removed, or combinations thereof, from the flame-side end of the flange; or both; an internal screw thread; at least one grub screw including an external screw thread and an axial hole; wherein at least one of the two panes is held, from the side remote from the intermediate space, in the internal screw thread by the at least one grub screw; wherein the at least one grub screw, on a side remote from said at least one of the two panes, includes at least one bore arranged substantially parallel to and laterally offset from the optical axis; and a further bore positioned adjacent to said at least one grub screw and running substantially parallel to the at least one grub screw at least one bore and arranged axially outside the internal screw thread with respect to the optical axis.