a process for manufacturing a plastic pipe from recycled crushed pet starting material includes kneading the starting material under the influence of heat while removing moisture therefrom so as to prevent hydrolysis of the pet material and thereafter feeding the mixture to an extruder and passing the extruded mixture to a corrugator while cooling at a temperature gradient of between − 10 ° c ./ min and − 50 °/ min so as to form a crystalline plastic pipe .