| 摘要 |
A multi-walled steel pipe includes at least two pipe bodies of different diameters. The two pipe bodies are overlapped with one another. Either the inner surface of the outer pipe body or the outer surface of the inner pipe body is a rough surface having a roughness of 10 to 30 mu m. The rough surface is made by brasting, etching, or brushing or by the use of rolls. At least one of the overlapping surfaces is plated with copper to provide a brazing layer by which the overlapping surfaces are brazed together. The pipe bodies are double-walled stainless pipes, seamless stainless pipes, or electroseamed pipes.
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