A deformed pipe having a deformed cross-sectional shape is press-fitted in a round hollow pipe having a circular cross-sectional shape. The deformed pipe has a plurality of radially outwardly projecting ridges having respective outermost vertexes held in contact with an inner circumferential surface of the round hollow pipe. The round hollow pipe and the deformed pipe are arc-welded to each other at axially spaced locations.
An exhaust pipe assembly of two-passage and double-pipe construction has an inner pipe; a partition plate meeting the inner pipe at both diametrical meeting ends thereof so as to be elongated in a longitudinal direction of the inner pipe. Two passages divided across a diameter of said inner pipe are thus formed. The assembly also has an outer pipe which covers the inner pipe with a thermally insulating space around a periphery of the inner pipe. The outer pipe has on one longitudinal end thereof a connecting portion for connection with a mating member. One end of the inner pipe is fixedly connected to the outer pipe with a clearance between the periphery of the inner pipe near each of the meeting ends and an inner circumference of the outer pipe.
