EXHAUST GAS CASING FOR A HEAVY-DUTY GAS TURBINE ENGINE, HEAVY-DUTY GAS TURBINE ENGINE AND METHOD OF RETROFITTING A HEAVY-DUTY GAS TURBINE

An exhaust gas casing for a heavy-duty gas turbine engine includes a shell (12) delimiting a hot gas path (13) and having a downstream flange (17); and an annular cooling structure (20), extending around at least a circumferential portion of the shell (12) adjacent to the downstream flange (17) and configured to convey cooling air around the shell (12). The annular cooling structure (20) is inwardly defined by the shell (12) and is outwardly defined by at least an annular cover structure (25, 26) attached to the shell (12).