| 摘要 |
A lapped steel tube which is improved in resistances to the repeated high-pressure fatigue and the cavitation erosion, in the vibration resistance and in the fitting properties to eliminate the clearances between its inner, outer and intermediate pipes and to lower the production cost. The lapped steel tube comprises an outer pipe, an intermediate pipe and an inner pipe. The outer pipe is made of an electroseamed pipe, the intermediate pipe is made of a duplex-wound pipe or an electroseamed pipe, and the inner pipe is made of a seamless pipe. The outer, intermediate and inner pipes are lapped by drawing them together and are integrated by soldering the individual lapped faces.
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