# 2001 Munich
In practice the career of peroxide cross-linked polyethylene started in 1972 with the underfloor heating of the sports arena in Munich as a snow and ice melting system, built for the Olympic games. Since then the propagation of PE-X has been unstoppable. The spread of applications followed with tap water pipes and radiator connections, connection hoses for refrigerators and washing machines, and pipes for difficult industrial applications. In 1988 PE-X began to be used in the supply of gas and water as an outdoor application. Since then the diameters have increased from a “thumb” pipe to dimensions of up to 250 mm. The excellent resistance in slowcrack growth (SCG) and rapid crack propagation (RCP) predestine PE-X as a material for very special applications under very difficult conditions. New methods of pipe laying such as horizontal drilling - the ploughing or milling in of pipes -makes it impossible to protect the pipe with the sand or special sheets. Without a protective surrounding stress cracks are induced in the pipe by stones or rocks that penetrate the pipe.1 The crosslinked structure of PE-X prevents the pipe from cracking under these local stresses, making it the first choice for these difficult applications.