METHOD FOR MANUFACTURING DOUBLE PIPE HAVING BRAIDED WIRE

摘要

Provided is a method for manufacturing a double pipe having a braided wire, in which the braided wire is interposed between an outer pipe and an inner pipe and then a drawing process is performed, thereby allowing the braided wire to make close contact with the inner surface of the outer pipe and the outer surface of the inner pipe. The inner surface of the outer pipe and the outer surface of the inner pipe are polished so that the surface roughness satisfies an arithmetic average roughness (Ra) of less than 1.0 µm. After that, the braided wire is interposed between the outer pipe and the inner pipe, and a sinking process is performed so that the difference of the outer diameter of the double pipe with respect to a die diameter (amount of thinning by drawing) satisfies the range of 0.1 mm to 0.3 mm. Subsequently, a heat treatment is performed. As a processing die, it is preferable to use a tapered die having a taper angle of 25° to 30°. The double pipe manufactured by this method ensures a flow path for a leaked fluid, has an excellent heat conductivity, and therefore is suitable as a heat transfer pipe constituting a vapor generator of a fast reactor.