Pipe for heat exchanger partic. in a motor vehicle - is welded from commercially-available surface-textured strip

摘要

The heat-exchanger pipe is made from a strip with a surface texture, pref. of ripples or tear drops; it is made by the usual bending and welding process, the textured surface forming the inside of the pipe. The inner surface of the pipe may be metallically improved and/or roughened. After it is made, the pipe may be formed into a dent along the middle part of its length, the ends being left unaltered; or the cross-section may be modified in both the radial and the axial directions.