In situ testing of hot water system sacrificial anodes

Hot water systems that are under mains pressure are constructed with a mild steel tank, as these tanks are in an aqueous environment there is a need for corrosion protection. A vitreous enamel coating is used as the first line of protection, but as these coating are prone to damage a sacrificial anode is put in place in case of failure. The sacrificial anodes corrode over time and are required to be checked periodically, as per manufactures specification. The only method currently available to check the sacrificial anodes is a visual examination, this can be expensive and leads to premature replacement which creates excess waste. This research identifies acoustic waves as a form of non-destructive testing that allowed the sacrificial anodes to be inspected in situ. This research shows by using piezoelectric transducers to pulse the sacrificial anodes with acoustic waves it is possible to determine the difference between test specimens. The signals are sampled directly from the piezoelectric transducer and post processing is done with MATLAB to identify the distinctions. Using digital signal analysis techniques it is found that each of the test specimens responds to the test pulses differently, giving specific frequency components and signal amplitudes. Using these differences it is possible to identify the individual sacrificial anodes apart, and proves this testing method is a viable approach to determine if a sacrificial anode requires replacement