The role of temperature gradients in residential copper pipe corrosion

Experiments were conducted to determine the effect of sustained temperature gradients of ≈20 °C on copper pipe corrosion under stagnant conditions in simulated potable water. An apparatus was constructed to (1) apply realistic temperature gradients to the pipes, (2) monitor copper release to the water, and (3) measure thermogalvanic currents between the warm and cold sections of pipe. The orientation of the pipe in relation to the temperature gradients determined whether convection currents developed that promoted mixing during stagnation, and this influenced the magnitude of the temperature gradient in the pipe. The temperature gradient led to significant sustained thermogalvanic currents. Mixing of the water within the pipe also influenced copper leaching and scale build-up.