The Pitting Resistance Equivalent Number, PREN = Cr + 3.3 Mo + 16 N, ranks grades for chloride environments: 304 is about 19, 316L about 24, 2205 about 35, 2507 above 40, 254 SMO about 43. Higher PREN, better chloride resistance.
Crevice corrosion starts under gaskets, deposits and lap joints at lower chloride levels than open-surface pitting; design out crevices and specify higher PREN where they cannot be avoided. Chloride stress corrosion cracking affects 304 and 316 above about 60 °C in chloride water; duplex resists it.
Surface condition matters as much as grade: pickled, passivated and clean surfaces last far longer than heat-tinted or contaminated ones.