The invention relates to a pipe insulation sleeve made of mineral wool bound by a thermosetting binder and comprising an outer insulating layer (1) consisting of a slab of mineral wool hardened all through, said outer layer (1) featuring a number of radial slits (2) taken out from its inwards-turned surface, which slits (2) run axially and are essentially closed and originally of V-shaped form, and an inner layer (3) of mineral wool bonded to said outer layer by a thermosetting binder and of such thickness and density that it is in itself rigid and at the same time imparts rigidity to said outer layer. A method and arrangement for production of the pipe insulation sleeve is also described.