Material selection is the most critical factor for structural safety and corrosion resistance. For indoor applications or dry environments, Stainless Steel 304 (SS304) is generally sufficient and cost-effective. However, for outdoor installations, coastal areas, or high-pollution urban zones, you must specify Stainless Steel 316 (SS316) or 316L, which contains molybdenum to prevent pitting corrosion. Always request a Material Test Report (MTR) or a spectrometer test to verify the nickel and chromium content before shipment.