The method for removing an inner casing from a machine such as a turbine or compressor includes providing supports between the outer casing and the inner casing of the machine, removing a top part of the outer casing, then removing a top part of the inner casing, then connecting a ring sector to a bottom part of the inner casing to replace the removed top part of the inner casing, then rotating the reciprocally connected ring sector and bottom part of the inner casing around the longitudinal axis to make the bottom part of the inner casing accessible, then removing the bottom part of the inner casing, guiding the reciprocally connected ring sector and bottom part of the inner casing during rotation, to prevent movement along the longitudinal axis.