A hot gas duct, such as a combustion casing in a gas turbine engine, includes a duct splitter held within the hot gas duct in at least three, preferably four, locations spaced around a peripheral edge of the duct splitter. At least one, preferably two, of the holding locations each comprise a generally cylindrical mounting that projects through a wall of the hot gas duct to engage an edge portion of the duct splitter by means of a slot formed in a circular face of the mounting. Mutually contacting surfaces of the slot and the duct splitter comprise hard face coatings to combat wear due to vibration and differential thermal expansion and contraction. The mountings have cooling holes that penetrate the mounting, so that coolant can flow through the mountings and into the interior of the hot gas duct to cool the mountings and the hard face coatings.