Copper alloy castings are used in applications that require superior corrosion resistance, high thermal or electrical conductivity, good bearing surface qualities, or other special properties. This Article discusses the nominal composition and mechanical properties of copper casting alloys, designated in the Unified Numbering System. It also describes the selection factors of copper casting alloys, including castability, machinability, dimensional tolerances, bearing and wear properties, and cost considerations. The Article provides information on the relative corrosion resistance of 14 different classes of copper casting alloys in a wide variety of liquids and gases which helps in selecting alloys for corrosion service.