SYSTEMPEX. Alu pipes on a roll without sheathing for sanitary and heating. The pipe consists of an extruded inner pipe made of PEX-b (silane cross-linked). Around this pipe an aluminium layer is bonded via laser welding (butt weld). A protective layer of PEX-b is extruded onto this aluminium layer. As the diameter of the pipe increases, the thicknesses of the respective layers also increase. The thickness of the aluminium varies between 0,2 to 1,2 mm. The bonding between PEX-b and aluminium and between the outer layer of PEX-b, is done with a copolymer adhesive.