Preinsualted PERT( PE for raised temperature, working temperature up to 80°C) are widely replacing old steel, ductil iron district heating water networks. The longer life span( at least 30 years) improves the residential living quality in North part of China, these new PERT II are utilized in spring water, geothermo, chemical industry as well. Size goes up to 630mm, it's another new material revolution in district heating application.