the invention relates to a corrugated , thermally insulated conduit for fluids , e . g . for district heating networks , wherein at least one medium pipe made of plastic or metal is surrounded by a thermal insulation layer , consisting of a polyurethane foam for example . the corrugation of the outer jacket made of plastic is formed such that both the corrugation valleys and the corrugation peaks are round , particularly circular . in addition , the corrugation is dimensioned such that the corrugation depth t lies in a range of 4 . 5 mm to 8 mm for a conduit outer diameter range of 63 mm to 202 mm . this shaping and dimensioning of the conduit results in very good flexibility and thus the ability to roll up the pipe for the transport thereof .