Chloride Resistance Ranking
Chlorides — seawater, brine, chlorine, hypochlorite, HCl — are the most common cause of valve material failure by pitting and stress-corrosion cracking. This ranks 5 valve materials by their resistance across 7 chloride-bearing fluids, so you pick the right alloy the first time.
What is the best valve material for chlorides and seawater?
For chloride-rich service, resistance climbs with nickel, chromium and molybdenum content: SS 316L pits in chlorides and is rarely adequate; duplex 2205 and super duplex 2507 resist seawater far better; and nickel alloys (Hastelloy C-276) and titanium handle the most aggressive chlorides and oxidising bleaches. Titanium excels in wet oxidising chlorides but must be avoided in dry chlorine, and Monel resists HF and some chlorides but not oxidising ones. The ranking below averages real compatibility ratings across the chloride fluids — use it as a first cut, then confirm against concentration, temperature and velocity.
How this ranking is built
Each material is scored as the mean of its compatibility ratings (Excellent = 4 to Not Recommended = 0) across the chloride-bearing fluids it has data for: Brine / Sodium Chloride Solution, Chlorine (Cl₂), Chlorine Dioxide (ClO₂), Cooling Water, Hydrochloric Acid (HCl), Seawater, Sodium Hypochlorite (NaOCl - Bleach). Only materials with data for at least three of these fluids are ranked. This is a transparent average of qualitative ratings — not a measured corrosion rate.
| # | Material | Tier | Score | Brine | Chlorine | Chlorine Dioxide | Cooling Water | Hydrochloric Acid | Seawater | Sodium Hypochlorite |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Hastelloy C-276 | Top tier | 3.8 | — | E | G | — | E | — | E |
| 2 | Titanium | Top tier | 3.4 | E | P | E | — | — | E | E |
| 3 | Duplex 2205 | Marginal | 2.0 | G | — | — | — | NR | G | — |
| 4 | SS 316L | Marginal | 1.9 | F | F | P | E | NR | F | F |
| 5 | Carbon Steel | Avoid | 1.1 | P | G | NR | G | NR | P | NR |
Chloride attack is highly sensitive to temperature, concentration, pH, velocity and oxygen. A material rated suitable at ambient may fail hot. Titanium resists wet chlorides but ignites in dry chlorine; austenitic stainless is prone to chloride stress-corrosion cracking above ~60°C. Always confirm with a corrosion specialist for critical service.
Connected Engineering
Specifying valves for seawater or chloride service?
Send your fluid, chloride level and temperature — we recommend the right duplex, super duplex or nickel-alloy grade with PREN-appropriate material and full certification.