Feb 4, 2010Dipl.-Ing. Leopold Glück, Sachverständigenbüro LEGL, Martinsheim; Dipl.-Ing. Udo Dengel, Süddeutsches Kunststoff-Zentrum (SKZ), Würzburg; Dipl.-Ing. (FH) Bruno von Wyl, Leister Process Technologies, Kägiswil, Schweiz
Until now, tunnel sheets made of flexible polyolefins (FPO/TPO) in tunnel construction have been joined with each other exclusively with the aid of hot gas welding machines and devices. Within the framework of the elaboration of the DVS 2225-5 technical code, the applicability of extrusion welding was checked, amongst other ways, in a workshop with the collaboration of device manufacturers, sealing sheet manufacturers, test institutes, experts and executing specialist businesses. The extensive welding tests have shown that, in principle, hot gas extrusion welding is suitable for the joining of sealing sheets made of flexible polyolefins. Although the welding tests were not preceded by any comprehensive optimisation measures, weld qualities appropriate for the applications and the requirements were obtained nearly without exception.
Hot gas extrusion welding can thus be applied not only in workshop conditions but also in building site conditions in the tunnel.