A thermally insulating protective sleeve. The thermally insulating protective sleeve comprises a tubular shell and a thermally insulating liner located in the tubular shell and made of a thermally insulating soft material. The shell comprises two longitudinally separated half-parts, the two half-parts being detachably connected to each other. The thermally insulating liner defines a hollow opening in the shell, and an object to be thermally insulated can be received in the hollow opening in such a way that the thermally insulating liner is subjected to pressure in a radial direction.

An insulation sleeve for insulating a component includes an inner layer, an outer layer, an insulating material, and a flap covering a seam passing from an outside surface to an internal surface of the insulation sleeve. The inner layer is a material having low thermal conductivity, resistance to high temperatures, is elastic/semi-rigid, and has an inner surface formed to a shape to fit the component. The outer layer has a material having low thermal conductivity, resistance to high temperatures, and is elastic/semi-rigid. The insulating material is positioned between the inner layer and the outer layer and has low thermal conductivity, low heat storage, and resistance to high temperatures. The flap is a material having low thermal conductivity and resistance to high temperatures, and is secured to the outer layer at a first location and releasably secured outer layer at a second location.

The invention relates to a method of fabricating an insulation element (2) as an insulation box, cap or cover for a valve, a flange or a fitting insulation within a piping system of a technical building equipment. Said method comprising the steps of forming a block of insulating material to be provided with a cavity having a contour of the valve, the flange or the fitting insulation and an outer contour, whereby the block is divided into at least two parts, preferably two halves (3) of the insulation box, cap or cover, and forming a complementary insulating covering (6) having an inner contour according to the outer contour of the block. To provide a method of fabricating the insulation element (2) having increased properties in view of combustibility and being cost saving because of an easy and less complex method for manufacturing insulation elements (2) which can be used at least for a range of valves, flanges or fitting insulations within a piping system of a technical building equipment having different sizes and/or outer contours the insulation element (2) and the complementary insulating covering (6) are produced separately from each other and joined together, whereby the block is produced from mineral wool, i.e. mineral fibers bound with a binding agent, and the complementary insulating covering (6) is produced from a plastically deformable material being mechanically pressed or molded to be provided with the inner contour corresponding to the outer contour of the block provided with the cavity.