Abstract: A coupling apparatus for connecting a combustor to a transition in a gas turbine is provided. The coupling apparatus comprises a transition cylinder attached to the discharge end of the combustor, a cylinder flange formed on the downstream end of the transition cylinder, a transition having an upstream end on which a transition flange is formed, and a plurality of nut and bolt combinations circumferentially spaced about the periphery of the flanges for maintaining the transition cylinder in tight engagement with the transition when the cylinder flange mates with the transition flange. In a preferred embodiment, the cylinder flange further comprises a spigot lip and the transition flange further comprises a recess for receiving the spigot lip so as to effect a tight spigot fit when the cylinder flange mates with the transition flange.