Combustion turbine with Siamesed wall paired combustor housings

A combustion turbine engine combustor section includes a plurality of annularly arrayed combustors housed within paired combustor portals of a combustor casing. Each combustor portal has a corresponding top hat cover having a peripheral flange. The paired combustor portals are formed in combustor housings having a figure eight-shaped sleeve wall planform. The paired adjoining combustor portals share a common Siamesed portion of the sleeve wall. A combustor portal mating surface is formed on an axial distal end of the sleeve wall, having a figure eight planform and defining a first array of fastener receiving apertures. A top hat cover retention bracket assembly having a composite planform conforming to the combustor portal mating surface planform and a second array of apertures that conform to the first array pattern apertures, is placed over the peripheral flanges of the paired combustor top hat covers and secured by top hat cover fasteners.