Ship fittings, port equipment, coastal facades and offshore structures.
Applications
Near the sea, stainless steel stops being a material choice and becomes a maintenance decision. 304 will look fine for a year and then fail — not because it was defective, but because chlorides are the one thing it cannot handle.
| Part | Grade | Finish | Thickness | Standard |
|---|---|---|---|---|
| Ship fittings, deck hardware | 316L / 2205 | No.4, satin | 3 – 20 mm | ASTM A240 / A276 |
| Port and terminal structures | 316L / 2205 | No.1, 2B | 5 – 50 mm | ASTM A240 |
| Coastal facade panels | 316L | HL, No.4 | 0.8 – 2.0 mm | ASTM A240 |
| Seawater pipework | 2205 duplex | Annealed | OD 6 – 630 mm | ASTM A790 / A928 |
| Handrails, guardrails | 316L | No.4, HL | 1.0 – 3.0 mm | ASTM A554 |
| Fasteners and brackets | 316L (A4-70) | Plain, passivated | — | ISO 3506 |
| Exposure | Grade | Notes |
|---|---|---|
| Coastal air, no direct spray (1–5 km) | 316L | Wash down periodically; dirt holds salt |
| Direct sea spray, splash zone | 2205 duplex | 316L can pit under continuous wet chloride |
| Continuous seawater immersion | 2205 / 2507, or 6Mo | Requires cathodic protection or correct alloy |
| Sheltered interior, coastal building | 316L | 304 only if cleaned regularly and not in a wet zone |
Molybdenum raises the pitting resistance number (PREN) from about 18 for 304 to 24–26 for 316L. That is enough for airborne salt with occasional washing. It is not enough for permanent wet chloride, where duplex 2205 (PREN ~35) becomes the economic choice — more expensive per kilo, far cheaper per year of service.
304 on a boat. It will rust. Not might — will.
Assuming "stainless" means maintenance-free. Even 316L needs periodic fresh-water washing in marine air. Salt sits in dust and pollen; the surface stays wet longer than you think.
Skipping passivation after welding. Weld heat tint is a corrosion site. Pickle and passivate, or specify pickled sheet.
Tell us the exposure (distance, splash, immersion) and the fixing method — we will recommend the grade and the passivation scope in writing.
Get In Touch
Whether you need 500 kg of 304 sheet or 25 tonnes of 316L coil, we can quote it. Tell us the grade, size, surface, quantity and destination port; our engineers reply within 8 working hours with price, lead time and packing details.
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