Abstract: It is an object to reduce the burden of a welding operation in producing a boiler waterwall panel and to reduce the burden of maintaining a furnace housing using the boiler waterwall panels thereby to improve the operating rate of the boiler. In a boiler waterwall panel 80, a panel body 70 with water passages is constituted by a plurality of metal seamless finned single tubes 60 as constituent units integrally produced by a hot extrusion method, etc., and joined by welding tip ends of fin portions 62. On at least one surface side of the panel body 70, fusion-bonded coating 81 for frame-like edge portions and fusion-bonded coating 82 for inner region, of a corrosion resistant alloy are formed. The finned single tube 60 has a single tubular portion 61 for a cooling water passage and a pair of fin portions 62 extending in the tube axial direction at peripheral opposite sides of the tube, and the external surface of the transition portion 63 is formed into a concave surface having a curvature radius of 3 to 6 mm.

Abstract: A clad pipe includes an external layer and a coating layer made of Ni base anticorrosion alloy. Both end portion areas of the coating layer are formed by a build-up welded layer (Ni base alloy of composition 1) on the inner surface of the external layer. Other areas are formed by a Ni base alloy layer (Ni base alloy of composition 2) fusion-bonded to the build-up welded layers and the inner surface of the pipe, a solidus-curve temperature of the Ni base alloy layer being 1300° C. or below and lower than a solidus-curve temperature of the Ni base alloy formed by build-up welding by 150° C. or more. Composition 1 and composition 2 are adjusted so that, in the same environment, corrosion resistance of the Ni base alloy of composition 1 is equivalent to or superior to that of the Ni base alloy of composition 2.

Abstract: A clad pipe includes an external layer and a coating layer made of Ni base anticorrosion alloy. Both end portion areas of the coating layer are formed by a build-up welded layer (Ni base alloy of composition 1) on the inner surface of the external layer. Other areas are formed by a Ni base alloy layer (Ni base alloy of composition 2) fusion-bonded to the build-up welded layers and the inner surface of the pipe, a solidus-curve temperature of the Ni base alloy layer being 1300° C. or below and lower than a solidus-curve temperature of the Ni base alloy formed by build-up welding by 150° C. or more. Composition 1 and composition 2 are adjusted so that, in the same environment, corrosion resistance of the Ni base alloy of composition 1 is equivalent to or superior to that of the Ni base alloy of composition 2.