JPS57127574A - Double wound pipe and production of double wound pipe - Google Patents

Abstract

PURPOSE:To improve corrosion resistance by forming the brazed parts of the outside pipe part and inside pipe part of a pipe into two layers of different contents of Fe, Cu, Ni as they go further from the steel base when viewed from one steel base side, and forming the inside and outside front surface parts of the pipe likewise into two layers. CONSTITUTION:Plated steel plates are double wound and are brazed by melting the plating coated layers on the top surfaces of the steel plates, whereby a double wound pipe is produced. More specifically, Ni plating of 0.1-5mu plating thicknesses is carried out on one surface of ordinary steel plates or stainless steel plate, and Cu plating of 0.5-10mu is carried out thereon, whereby Ni-Cu two-ply plating layers are formed on one side. A double wound pipe is produced with such steel plates and the pipe is subjected to a brazing treatment under the conditions under which the reduction of the plating layers of two plies into one ply is prohibited. Then, the layer of a high content of Ni wherein the content of Fe decreases and that of Cu increases as the brazing parts of the outside pipe part and inside pipe part of the pipe go further from the steel base and the layer of a low content of Ni are obtained. The front surface parts of the inside and outside surfaces of the pipe are of the two layers which are opposite from the above-mentioned as they go farther from the steel base.