Battenfeld Extrusionstechnik GmbH, Bad Oeynhausen, Germany constructed and installed custom-made extrusion components for Salzgitter Mannesmann Line Pipe GmbH in Hamm, Germany, which were perfectly integrated into the existing line for producing steel pipes with plastic jackets. With two new BEX 1-150-30B extruders and the U 700-2 VSI 4/8 FS coating die, the pipe manufacturer was able to double the previous line output to more than 3,000 kg/h and extend its product portfolio to include pipes of up to DN 600.
Salzgitter Mannesmann Line Pipe (MLP) specializes in the production of plastic coated steel pipes for demanding applications, such as oil fields. To produce such pipes, steel pipe segments with a length of up to 18 m are manufactured on site in a High-Frequency Induction (HFI) electric resistance welding process and subsequently covered with a three-layer plastic jacket. To make the jacket, first a coat of epoxy resin primer and then an adhesive are electro statically applied to the blasted and induction-heated steel pipe. The pipe thus prepared is subsequently guided through the extrusion station with a coating die, where the outer layer, which consists either of PP or PE, is applied by a vacuum hose extrusion process.
The machine manufacturer installed two single-screw extruders laid out for polyolefin processing in Hamm, each with a 150 mm screw diameter, a processing length of 30 D and a maximum output of 1,500 kg/h. To fit the equipment into the small space available, the extruders were arranged in V configuration, connected with the die via a short melt channel and equipped with high-performance drive units flanged on laterally as a customized solution. The U 700-2 VSI 4/8 FS die is the VSI coating die with the highest throughput built by Battenfeld Extrusionstechnik so far in this dimensional range. It was designed so as to weigh only 7.5 tons instead of 10 tons, in spite of its enormous dimensions for pipes with a maximum outer diameter of up to 610 mm. This weight limit was very important for the pipe manufacturer, as the maximum permissible crane load could not be exceeded. In addition, the die is equipped with the proven two-step distributor concept consisting of a spiral mandrel and a lattice basket distributor, and a custom-made handling solution for dimensional changeover at maximum speed.