PURPOSE: To prevent oxidation of the surface of a pipe even at the time of red heating of the pipe by a burner for working by cladding the surface of the pipe made of an Ag-Cu alloy with an Ag layer.

CONSTITUTION: After Ag-7.5%Cu is melted to generate an ingot having 110mm diameter and 200m length, and the outer peripheral surface of this ingot is cladded with the Ag layer having 0.50mm thickness, and this ingot which is cladded with the Ag layer and is made of Ag-7.5%Cu is worked into a pipe having 50mm outside diameter and 30mm inside diameter by extrusion, and this pipe is worked into a pipe having 20mm outside diameter and 19.1mm inside diameter by drawing. Further, this pipe is annealed for 10 minutes in a gaseous atmosphere of N2-H2 at 650°C, and a pipe for flute having 19.7mm outside diameter 19mm inside diameter, and 300mm length is obtained by drawing. Thus, blackening (oxidation) is prevented though the pipe is heated to red by the burner for the purpose of annealing at the time of working.