Erosion corrosion of plumbing materials in domestic water systems is a complex phenomenon driven by water quality, hydrodynamic and electrochemical factors. Erosion corrosion accounts for over a third of copper hot water system failures in the U.S., hundreds of millions in damage, and may be expected to increase with newer Legionella control strategies including increased use of water recirculation and high temperatures. Additionally, some nonleaded alloys introduced after the passage of a new federal law restricting lead content in plumbing, have been anecdotally implicated as failing prematurely from erosion corrosion compared to traditional alloys. This dissertation includes 1) a critical review of the literature, 2) investigation of a recent rapid erosion corrosion failure in a large building plumbing system, 3) replication of this phenomena in copper and nonleaded brass in laboratory studies, and 4) evaluation of 12 nonleaded alloys against conventional leaded brass. Current plumbing codes and guidelines to prevent erosion corrosion were found to be widely inconsistent and lacking scientific evidence. Large-scale recirculating hot water pipe-loop experiments demonstrated that an aggressive hard water with entrained aragonite (CaCO3) particles could cause fully penetrative failures (i.e., leaks) in brand new copper pipe and nonleaded brass fittings in just 3-49 days. This represents the first time rapid erosion corrosion failures have ever been replicated in the laboratory under conditions similar to those encountered in practice. The entrained particulates dramatically accelerated attack on metals, especially at pipe bends. In general, lowering pH, increasing flow velocity, increasing temperatures, entrainment of particles (of bigger sizes), and addition of chlorine disinfectant increased erosion corrosion rates. These results scientifically proved that hard waters are not inherently less aggressive than soft water, and in fact if CaCO3 solids form they can be much more aggressive. Finally, cavitation and erosion corrosion resistance of 12 nonleaded alloys was evaluated against leaded brass; stainless steels demonstrated superior performance, silicon brass had the greatest susceptibility and remaining alloys were in the middle. This performance data can aid decision making regarding choice of alloys for various water applications. Our work over the years, including involvement in the Flint Water Crisis, demonstrated that practicing trustworthy science as a public good requires commitment to scientific rigor, truth-seeking, managing conflicts of interest, and comprehensible evidence-based science communication. Critical problems in 21st century public science were highlighted including perverse incentives, misconduct, postmodernist "science anarchist" thought, and ineffectiveness of U.S. water utilities in communicating tap water safety to the American public. / Ph. D.

Excessive water flow velocities can contribute to rapid failures of copper premise plumbing systems. This is the first fundamental study to scientifically isolate mechanistic impacts from distinct flow induced failure mechanisms that include concentration cell corrosion, cavitation, particle/bubble impingement and high velocity impingement. Concentration cell effects resulting from exposing different copper surfaces to different flow regimes created a strong electrochemical cell that caused rapid corrosion that persisted for periods lasting from hours to days in certain waters. Free chlorine appeared to inhibit this effect in a range of waters. Under typical water chemistries the resulting non-uniform attack diminished, presumably due to formation of a protective scale or rust layer. Consequently, concentration cell corrosion would not be a major contributor to damage from high flow rates in the range of fresh waters investigated. In experiments using an ultrasonic processor, implosion of vaporous cavitation bubbles against a copper surface caused dramatic pitting, considerable copper weight loss, and, in some cases, the development of pinhole leaks. Changes in water chemistry and the existence of a pre-existing protective scale layer had nearly no mitigating effects on copper cavitation damage. An exponential relationship was found between the initial copper pipe wall thickness and the time necessary to cause a leak via vaporous cavitation. On the basis of this relationship, a Type M tube would be expected to last 23 and 3000 times less than a Type K and L tube, respectively, when facing continual cavitation attack. However, it was not possible to re-create cavitation damage in any practical circumstance that was tested in copper pipes, even though it is strongly believed that cavitation can play a practical role in service failures. On the basis of the above results, it was hypothesized that brief intervals of cavitation could remove protective scale from portions of the copper pipe surface exposed to high turbulence. In this case, even if minimal damage from cavitation occurred directly, it could allow concentration cell corrosion to become a significant contributor to non-uniform corrosion damage. On the basis of preliminary testing, it appears that this idea has considerable merit. A combination of brief cavitation and waters that create strong concentration cell effects is expected to cause serious damage to copper pipe. These potential synergies are deserving of additional research. In experiments testing the effect of high velocity jets (17.5 ft/sec) impinging against submerged copper plates perpendicularly and longitudinally, plates in heated sea water were aggressively gouged and penetrated. It is believed that the copper plate damage resulted from a combination of mechanisms including concentration cell corrosion, cavitation implosion, and high velocity impingement. Impingement of sand on the surface of copper tube created very little damage. This was surprising given prior reports in the literature. / Master of Science