Quick answer: stainless steel can remain serviceable for decades, but there is no universal lifespan. Grade, chloride exposure, temperature, fabrication, surface condition, drainage, cleaning and inspection determine whether a component lasts a few years or far longer.
304 performs well in many indoor and mild outdoor environments. 316/316L is often preferred where chlorides are present, while duplex or higher-alloy grades may be needed for more aggressive service. No grade is completely immune to corrosion.
Crevices, stagnant water, rough welds, heat tint, iron contamination and contact with dissimilar metals can shorten life. Good drainage, smooth transitions, compatible fasteners and proper post-weld cleaning often matter as much as nominal grade.
Deposits retain salts and moisture. A cleaning interval should reflect actual contamination and rainfall, not a fixed calendar rule. Inspect concealed joints, welds and splash zones where corrosion can begin before the broad surface changes.
Provide the operating medium, chloride level, temperature, cleaning chemicals, expected deposits, design life, fabrication method and inspection access. Choose the material through the applicable design code and corrosion assessment. A higher alloy is not a cure for poor drainage or contaminated fabrication.
Review available stainless steel product forms and send the service conditions for a more useful grade discussion.