Why Has Lead Been Traditionally Used in Plumbing Fixtures?

Lead is added to plumbing brasses to improve machinability and ensure pressure tightness. Traditionally, cast red and yellow brasses contain a fine dispersion of lead particles in the microstructure. Without the machinability enhancement made possible by lead, brass plumbing products could be much more expensive due to very high machining costs. Sand-cast faucets and other plumbing components have traditionally been made from leaded red, semi-red and yellow brasses. The most common plumbing brass, C84400 (also known as 81 Metal or 81-3-7-9) contains nominally 7% lead. The most popular red brass, C83600 (85 Metal, 85-5-5-5), contains nominally 5% lead. Permanent mold and pressure die castings of plumbing components are also commonly made of the leaded yellow brass alloy C85800, which contains nominally 1.5% lead. In contrast to the red brasses, which are moderate-strength, single-phase alpha alloys, alloy C85800 is stronger at both room temperature and at elevated temperatures ...  more