Abstract: A connecting element including an annular sleeve that has a self-supporting inner wall and a flexible outer wall, and a space between the inner and outer walls for introducing a preferably hardenable free-flowing filling medium into the connecting element to expand the connecting element radially outwardly to contact surfaces of adjacent pipe structures. A feed opening is provided in one of the inner wall and the outer wall to provide access to the space between the walls to permit introduction of the filler material. The connecting element is particularly suitable for sealing the joint between a multi-walled main pipe and a branch pipe extending from the main pipe.

Abstract: The pipe winding apparatus includes a stationary cage formed by rods between two rings. The speciality is that at least a number of the cage rods is located oblique between the rings by the pitch of the strip to be wound helically and is driven such that the strip to be wound can be fed at a right angle against the driven rods. This allows an optimal utilization of the frictional forces between the strip and the rods and to wind the pipe by the drive of the rods and to advance the pipe produced thereby.

Abstract: A tube winding apparatus includes a drum having a jacket formed by elongated cylindric members. A number of these members, namely the circumferential rollers, is motor driven basically by the normal drive of the winding apparatus. Such supports the tube and web drive and the feeding or advancing of the tube.

Abstract: A profiled band that includes two longitudinal edges of which one is provided with a groove and a parallel extending rib is allocated to the other one, which mentioned parts form a locked seam when the band is wound to a pipe, which seam is mechanically held in its operational position. The band is specifically suitable for an in situ production of wound pipes having a helically extending seam.

Abstract: The mixture for manufacture of shaped elements of fiber-cement, in addition to minimum 5% by weight of pozzuolanic silicic acid contains also an amount of limestone powder. With this mixture it is possible to obtain a product of high strength properties without tendency to embrittlement respectively to formation of cracks on the surface.In utilizing the mixture for manufacture of shaped elements the latter are moulded from a mixture of aqueous material and permitted to set at 70.degree. to 90.degree. C. during 5 to 12 hours preferably with simultaneous compression.

Abstract: To reinforce products made from hydraulic binder agents, fibers of polymerized acrylic nitrile, which are manufactured with a molar concentration of acrylic nitrile units of at least 98%, are used. The fibers advantageously have a strength of at least 50 cN/tex and a breaking elongation of at most 15%. These fibers produce a product after setting having good bending tensile strength and excellent impact strength.

Abstract: Asbestos-free, fiber-reinforced, hydraulically setting compositions can be processed to fiber-reinforced shaped articles. The compositions are obtained by mixing fibers, hydraulic binders and water-soluble or water-emulsifiable polymers and by adding a metallic compound, particularly a metal salt or hydroxide. The composition can be processed in the equipment conventionally used in the asbestos cement industry.