The present invention makes it possible, in a plant such as a thermal power plant, to prevent the corrosion of a piping member or a device such as a boiler by effectively decomposing nitrogen monoxide (NO) included in waste water or condensate water and inhibiting the generation of nitrous acid (HNO 2 ). The present invention is a piping member used in a feed water system or a waste water system of a plant, and characterized by coating an inner wall of the piping member (200) with a catalyst (201) accelerating decomposition of nitrogen monoxide.
