Polyurethane two components systems are very common as an insulation material in district heating systems. Since generations district heating systems are used to distribute heat to the customer by a network of pre-insulated-pipes. Insulating the transport pipes with a polyurethane pouring system is a needed to diminish heat losses. With a high pressure machine the cavity between the steel transport pipe and the HDPE outer casing is injected with a polyurethane system. Spacers are mounted to the steel transport pipe to guarantee an even and constant cavity between the inner pipe and outside casing. Before this arisen space is filled with polyurethane, heat sensitive contact wires are applied trough the tube over its total length. After installing the district heating pipes these wires are used to track down heat losses as a result of aging or cracks.
Pouring pre insulated pipe systems takes place with 3 basis techniques: