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This post was last edited by Ains on 2026-3-10 11:08. In industries such as chemicals, chlor-alkali, and pharmaceuticals, valves are constantly subjected to the combined impact of chlorine gas (dry/wet chlorine) and hydrochloric acid (HCl solution). Traditional stainless steel (such as 316L) or Hastelloy valves may seem durable, but they often develop pitting, stress corrosion cracking (SCC), hydrogen embrittlement, or uniform thinning within a few months, leading to leaks, production shutdowns, and even safety accidents. The true mechanism of valve corrosion in a chlorine + hydrochloric acid environment: dry chlorine vs. wet chlorine. Dry chlorine (with 149°C moisture content) can easily cause chloro-iron fires (posing a fire risk to carbon steel). Wet chlorine or chlorine containing water: It produces hydrochloric acid and hypochlorous acid, which destroy the metal’s passivation layer and lead to severe corrosion. Stainless steel (316L): Chloride-induced pitting and chloride stress corrosion cracking (SCC), especially in high-stress areas such as welds and fasteners. Hastelloy C-276: May still experience localized failure under high chloride levels and high temperatures. Titanium alloy: It burns easily in dry chlorine gas (> -18°C), and corrosion intensifies in cracks when exposed to wet chlorine gas. Typical valve failures: Micro-cracks or perforations occur in the valve stem, seat, and sealing surfaces, resulting in a significant increase in the risk of leakage. Hydrochloric acid (HCl solution) is a strongly reducing acid; almost all metals, including stainless steel, are not resistant to it. concentration