AquaPLEX® is a revolutionary, engineered material used in the fabrication of PVI water heaters that blends austenitic and ferritic steels combining the advantages of both 300 and 400 series stainless steel. This synergy makes AquaPLEX extremely strong and highly resistant not only to aqueous corrosion in potable water at any temperature, but also chloride stress corrosion cracking, a known failure of 316L and 304L stainless steel. AquaPLEX eliminates the need for tank linings or anode rods, which both require service over time.
AquaPLEX requires special welding processes as well as proper pickling and passivation procedures after the vessel is constructed. PVI uses six-axis robotic synergic pulse welding machines that automatically and instantly manage the arc current and voltage based on the welding speed to optimize the size and create high-quality, consistent welds.
To return AquaPLEX to its fully passive condition after vessel fabrication, the vessels are completely immersed in a time, temperature and concentration-controlled pickling and passivation solution. When rinsed with purified water and exposed to air, AquaPLEX reacts with oxygen to create a continuous chromium oxide layer on its surface. The high chromium content of AquaPLEX combines with oxygen in the air to form a “passive” layer of protection. This layer is permanent and prevents AquaPLEX from corroding when exposed to the dissolved oxygen and other aggressive elements found in all potable waters. This oxide layer is responsible for its lifelong corrosion resistance.
PVI consulted with a team of world class engineers and scientists to assist in the material selection, product design, welding technology, vessel fabrication, chemical processing and testing, and overall manufacturing processes for AquaPLEX.
Although PVI recommends a maximum stored water temperature of 140°F for general use potable water service, AquaPLEX vessels are suitable for continuous exposure to water temperatures greater than 200°F, as often seen in solar thermal storage applications. Such temperatures would quickly erode tank linings like porcelain enamel (glass) or epoxy polymer. Temperature limits for AquaPLEX water heaters are dictated by ASME code limitations or appropriate safety certifications, and not the vessel material itself.