Long-term corrosion resistance of solid brass door hinges has been guaranteed by several standardized test methods. As per ASTM B36 specification, ≥60% copper containing brass alloy has a duration of up to 4800 hours in salt spray test (ISO 9227), and corrosion rate is ≤0.002 mm/year. It is much higher than the 1,500 hours (0.005 mm/year corrosion rate) of type 304 stainless steel and 500 hours (0.03 mm/year corrosion rate) of zinc alloy. A sample statistics from a specific seaside hotel indicate that the rusted surface area of the door body with brass hinges was only 0.5% after 10 years of operation in a state of 95% humidity and 3% salt spray concentration, while the rusted area of stainless steel hinges was 12% within the same period, saving maintenance costs by 68%.
Environmental adaptation facts reveal solid brass door hinges are stable at harsh condition. For example, at a swimming pool environment condition which contains chloride ion concentration at 5%, weight gain by corrosion of the brass hinges every year is only 0.8 milligrams per square centimeter (according to ASTM G1 standard), just 25% compared with stainless steel (3.2 milligrams per square centimeter). In a 2022 cruise ship case, the brass hinges had lasted 15 years of Marine climates without any operational damage, whereas the below-standard chrome-plated steel hinges had a rusting and jamming rate of 23% over three years, doubling the replacement cost of a single set. Natural oxide layer (verdigris) of brass can decrease corrosion even more and has an oxidation rate of only 0.001 millimeters per year with a pH condition of 6-8.
The rate of attenuation of mechanical properties is very low. The tensile strength of brass hinges (≥380 MPa, EN 12150 standard) decreased by only 3% after 500,000 opening and closing tests, while that of zinc alloy hinges decreased by 18% under the same conditions. Data from an airport terminal show that solid brass door hinges has displacement error of as much as 0.3 mm in 10 years in 300 high-frequency daily uses with a failure rate of 0.4% against a failure rate of 7% for aluminum alloy hinges. The life of brass fatigue (≥1 million cycles) is five times longer than coated steel hinges (200,000 cycles), and the life cycle cost is decreased by 72%.
The antibacterial activity extends the period of hygiene safety. The copper ions (0.2-0.6 μg/cm²·h) released from the surface of brass can kill 99.7% of drug-resistant Staphylococcus aureus (ISO 22196 standard). After the ICU of a hospital was replaced with brass hinges, the total colony count on door handles decreased from 150 CFU/cm² to 5 CFU/cm², and the risk of infection decreased by 92%. Stainless steel hinges, on the other hand, are not antibacterial, and the growth of colony density after a year reaches up to 25%, which means an extra 12% disinfection cost.
Economic analysis confirms long-term advantages. Although the initial cost of solid brass door hinges ($80-150 per set vs. $25-50 for stainless steel) is higher, its total 30-year cost (including maintenance) is only 35% that of the stainless steel choice. Let a specific commercial building be taken for example. The 30-year maintenance cost of brass hinges is 45 US dollars per set, while that of stainless steel hinges is 220 US dollars per set, and the return on investment (ROI) is up to 188%. Past experiences are evidence: In 2019, a chemical plant adopted galvanized hinges, and within two years, 37% of the door bodies rusted and failed, resulting in an accident loss of over 180,000 US dollars. Failure rate of the identical kind of factories with brass hinges used during the same period of time was 0.3%. The data show that there is no product except brass hinges to survive in corrosive atmospheres (chemical exposure or salt spray or > 70% humidity) within the 50-year life test certification (EN 1670 standard).