US Patent 7681599 Line pipe for the transport of deep-frozen media

A line pipe for the transport of deep-frozen media, consisting of at least two corrugated metal pipes (2, 4) arranged concentrically and at a distance from one another, an insulation layer (3) being arranged in the annular gap between the two metal pipes (2, 4), the annular gap being evacuated, and a closing valve (10) provided in the outer metal pipe (4) being connectable to a vacuum pump, the closing valve being welded, vacuum-tight, into a smooth-walled metal pipe (9) welded, vacuum-tight, to the exterior of the metal pipes (4). The valve body (10) of the closing valve projects into the interior of the smooth-walled metal pipe (9) and is flush with the outer surface area of the smooth-walled metal pipe (9).