On the project in Høje Taastrup, a Detector type X6 for imped- ance measurement is connected to the 3dc wires in the flex- ible pipes. Flexibility of the pre-insulated flexible pipe High flexibility is secured by combining the design with a cor- rugated casing and a soft PUR foam. We have tested the flexibility of PertFlextra by bending tests and compared it to the flexibility of the corresponding dimen- sions of PexFlextra and AluFlextra. The dimensions of the ser- vice pipes are 32 mm, and the casing dimension is 90 mm.
the institute IMA Materialforchung und Andwendungstechnik GmbH, according to requirements in the EN standards, show a lambda50 on 0,0201 W/mK. Diffusion barrier for water vapor on the service pipe: The aluminum diffusion barrier on the PE-RT service pipe shall prevent oxygen diffusion into the water and avoid water vapor diffusion into the PUR insulation. Concerning heat loss, the European standard for flexible pipe systems EN15632-1 Annex B and prEN17878-1 Annex B defines that if a supplier does not have the diffusion barrier for water vapor on the service pipe, the declared lambda value shall be multiplied with a factor 1,1 to achieve the design lambda value. Reference is made to a report done by the Danish Technolog- ical Institute, “Fleksible præisolerede rør med fugtig isolering” (Translated to English as “Flexible pre-insulated pipes with wet insulation”). The pipes tested in this project are flexible with PEX service pipes (without water vapor diffusion barrier) oper- ating for some years.
Diffusion barrier in the casing for diffusion of insulation gasses:
An EVOH diffusion barrier co-extruded into the casing of Pert- Flextra shall prevent the diffusion of insulation gases out of the PUR foam and the diffusion of atmospheric air into the PUR foam. About heat loss, the European standard for flexible pipe sys- tems EN15632-1 Annex B and prEN17878-1 Annex B defines that if a supplier does not have the diffusion barrier for insula- tion gasses, the declared lambda value shall be multiplied by a factor of 1,25 to achieve the design lambda value. Possibility of having a surveillance system on a pre-insulated flexible pipe system with a plastic service pipe With an integrated surveillance system on a flexible system with plastic service pipe wet foam can be detected whether the moisture is coming from a leaking service pipe or from out- side due to wrong joint installation or due to damage on the casing. On pre-insulated flexible pipe systems with a plastic service pipe without a water vapor diffusion barrier, it will make no sense to include a surveillance system as an integrated part of the flexible pipes. This is because it is known (see above) that there will be water permeation into the foam, and the foam might get wet over a lifetime. PertFlextra has a water vapor diffusion barrier on the service pipe, enabling the possibility of integrating a surveillance sys- tem in the pre-insulated flexible pipes, PertFlextra. In the COOL DH project, the pre-insulated flexible pipes were delivered with the 3dc surveillance wires for an impedance surveillance system.
Tests show that the flexural stress needed to bend PexFlextra (SDR 11) is 19% lower than bending PertFlextra (SDR 7,4), and the flexural stress needed to bend PertFlextra is 18% lower than bending AluFlextra. Qualifying an electro-fusion coupling for connection of the PE-RT service pipes: This was defined as part of the COOL DH project, but time was too short to do this qualification during the development period of this project. Tests done to qualify PertFlextra Before the launch of the new pre-insulated flexible pipe sys- tem, it is necessary to conduct several tests on the service pipe itself, the service pipe together with couplings, and tests on the pre-insulated pipe. This is to ensure that the pipe system with components will live up to the requirements in the standards and ultimately have the expected lifetime.
All below tests are done, and requirements in the standards are fulfilled.
Thermal stability test of the PE-RT service pipe (Danish Technological Institute): PE-RT service pipe is tested with 2,4 MPa and 110 °C for 15.000 hours. No break on the service pipe is allowed.
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