Flow-induced corrosion of brass flowmeters used for drinking water

Traditionally, water supply components were made of dezincification-resistant brass alloys due to their relatively low cost, good forging properties, and good machinability. However, due to recent legislation on the restrictions of lead and nickel, increased use of disinfection, and a more diverse range of flow conditions, corrosion failures have become more prevalent. This work describes the failure investigations of two domestic water flowmeters made of dezincification-resistant brass type CW511L, with a difference in internal diameter. The underlying cause of failure is determined by visual inspection, microstructural analysis with scanning electron microscopy, energydispersive X-ray spectroscopy, and corrosion product identification using X-ray diffraction. The scales formed at less degraded regions were identified as copper-enriched corrosion products mainly consisting of metallic elements, oxygen, and chloride, with most of the scale formation being malachite. Depletion of protective scales was seen in regions with high flow, resulting in flow-induced corrosion and high material losses. Computer fluid dynamics simulations confirm that specific regions were exposed to high flow rates, resulting in failure.