This paper will present the state of development concerning the use of Polyurethane Foam (PDF) as part of the sandwich construction of bonded pipe in pipe systems with steel jacket pipe. The concept of bonded pipe elements is that the thermal expansion of the hot inner pipe is constrained by the outer pipe. The range of thermal insulation properties and the strength properties will be given taking into account temperature and expected service life. The paper introduces considerations concerning design, production and installation.