A compensator (18) is provided for compensating thermal expansions of ducts or pipelines (10) for carrying flows of hot media, especially ducts that are lined with fire-proof material. The compensator (18) is easy to maintain and is relatively simple in its design. This compensator (18) permits inspection of the operability of the expansion gap (19) between adjacent sections of the pipeline (10) and its elastic temperature-resistant jointing material (20) from the outside of the pipeline. The expansion gap (19) in the flame-proof lining is arranged in a cross section plane of the pipeline that is adjacent to but below the cross section plane of the corrugated pipe compensator (18) attached to the steel sheet jackets (15) of adjacent sections of pipeline (10). The steel sheet jackets (15) are spaced from one another in the area of the expansion gap (19) and the elastic temperature-resistant jointing material (20) is easily accessible from outside the pipeline upon removal of jacket parts (21) forming a collar around the expansion gap (19).