Patent ID: 8783299

Claim:
A twin-wall pipe, comprising: a central longitudinal axis ( 18 ); a smooth-wall internal pipe ( 39 ′) which extends concentrically of the central longitudinal axis ( 18 ); a corrugated external pipe ( 37 ′), having elevations ( 38 ) and troughs ( 40 ) between the elevations ( 38 ), the troughs ( 40 ) and the internal pipe ( 39 ′) being welded together; a pipe socket ( 41 ) which is molded integrally with the internal pipe ( 39 ′) and the external pipe ( 37 ′); a transition portion ( 61 ) between a trough ( 40 ) and the pipe socket ( 41 ), the transition portion ( 61 , 64 ) being formed between the external pipe ( 37 ′) and the internal pipe ( 39 ′); wherein an inside of the transition portion ( 61 ) between the external pipe ( 37 ′) and internal pipe ( 39 ′) is connected to an adjacent elevation ( 38 ) by at least one overflow passage ( 59 ), which—relative to the central longitudinal axis ( 18 )—has a radial outer height b and a width a in a circumferential direction wherein a≧b refers to the radial outer height b of the overflow passage ( 59 ) relative to its width a in the circumferential direction of the external pipe ( 37 ′); wherein the overflow passage ( 59 ) passes through the elevation ( 38 ) in an area of the external pipe ( 37 ′) in a direction of the central longitudinal axis ( 18 ).