Heat should be distributed over district heating networks in an environmentally friendly and economically way. Thus the goal is to minimise the heat losses during transport. Therefore, the PE bonded pipe in which the steel pipe containing the medium is insulated with polyurethane foam and then encased with HDPE was developed over 50 years ago. The author explains the further development of the PE bonded pipe and several production methods. Today's PE bonded pipe (figure 1) is based on a concept from the 1960s: the goal was to insulate pipes containing a warm medium with polyurethane (PUR) foam and to install them underground in distribution networks. In addition a »mould« was required to form the PUR insulation and to protect the insulation in the earth afterwards. The solution at that time is still used today and is known as the traditional production of pre-insulated pipes. A service pipe is slid inside a casing pipe and centred with spacers, the pipe ends are closed and the space is filled with PUR foam. After initial attempts with other materials a casing pipe of high density polyethylene (HDPE) became the norm.
展开▼
