| 摘要 |
PURPOSE:To efficiently manufacture a heat transfer pipe to easily fit on a tube plate by inserting an intermediate pipe and a dummy pipe in series between an inner pipe and outer pipe to draw and by cutting both ends of the outer pipe to remove the dummy pipe. CONSTITUTION:The intermediate pipe 4 and dummy pipes 11 placed in series on its both ends are inserted between the inner pipe 2 and the outer pipe 3 to constitute a triplet structured pipe 1'. When this pipe 1' is extracted by prescribed die and plug, a straight pipe free from an irregularity even on both end parts inserting the dummy pipes 11 is formed. Then, both the end parts of the outer pipe 3 are cut at the parts of the dummy pipes 11, and the dummy pipes 11 are taken out, a pipe whose inner pipe 2 is projecting from the outer pipe 3 is obtained without scratching the inner pipe 2. Therefore, the heat transfer pipe which inner pipe 2 and outer pipe 3 are weldable easily on the prescribed tube plate is manufactured efficiently and accurately.
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