Outer jacket of pre-insulated pipe is exposed to mechanical impact during transportation and installation. Breakup enables water penetration inside the pipe and furthermore inside the house. That might cause massive moisture damage. The purpose of this study was to define is it possible to create economic double-jacket structure for pre-insulated plastic pipe. The meaning of double-jacket structure is to keep the internal structure of pipe dry and prevent the water penetration between insulation and corrugated polyethylene jacket.

The main solution in this study, how to prevent water penetration, was wrap up the insulation with plastic film. When plastic film melts inside corrugate it acts like glue between insulation and jacket. Melted structure of jacket and insulation will prevent water penetration to internal structure. Wrapping of film also reduced insulated pipe diameter and that is supporting melting process, when tension of wrapped film is released after melting of film. Main method to develop process was test production with actual production machinery.

We did five test drives in production line with different values and parameters and tried to find optimum parameters for production. Plastic pipe products were acting very differently using plastic film so we didn’t get accurate results. This is result of large number of factors influencing to process. If we still want to develop the process in future more test drives should be done.