District Heating has been used for community heating for almost 100 years in Europe. Until 1980, only steel systems with insulation were installed, mainly in concrete ducts. In 1974 pre-insulated systems were introduced, but they still used steel pipes. There was still one main problem - corrosion. There was an incentive therefore for energy suppliers all over the world to search for non-corrosive solutions.

An energy company based in Austria was one of the pioneers who investigated alternative solutions and instructed the Plastics Institute of the University of Leoben to carry out a testing program to find the best solutions for low temperature District Heating networks.

The results for the inner pipe were clear - Polybutene-1 was the best plastic for elevated temperatures (up to max. 95°C) - and this result encouraged the Austrian energy company to undertake a joint venture with a pipe manufacturing company to produce and market pre-insulated piping systems with Polybutene-1 inner pipes.

42 networks utilising 210 km of pipe have so far been installed. 70 km of pipe were installed prior to 1987. These networks were so called "secondary networks" which were supplied from primary lines by means of central transformer stations with heat exchangers to reduce temperatures to max. 90°C and pressure to 5 bar.

After 8 years in operation some of these Polybutene-1 pipes were sent to Austrian test institutes to compare these pipes with new ones. The amazing result was that the used pipes turned out to be even stronger than the new Polybutene-1 pipes - the tempering/annealing process going on during service seems to have a positive effect on the pipes, at least during the first 8 years.

The very aggressive geothermal water in Vienna caused big problems with corrosion in metallic pipes. So in 1972 when the new geothermal centre in Vienna was being planned, a 2 year test cycle was undertaken with various pipes made of stainless steel, PVC-C, epoxy and Polybutene-1. Polybutene-1 proved to be the best material and was subsequently installed for all geothermal lines from the source to the geothermal centre, with a 225 mm OD twin main line of 1.4 km, and some 2 km of internal pipes in sizes 20 mm to 225 mm OD.

All these pipes are still running at 54°C and 10 bar with no breakdown.