Seawater defeats ordinary stainless steels through pitting, crevice corrosion and chloride stress-corrosion cracking. Two common upgrades are Monel 400 (UNS N04400, ASTM B127) and 316L. Here is how they compare.
Performance in Seawater
- 316L (PREN ≈ 24) suffers crevice corrosion in stagnant seawater above roughly 15–20°C and is unreliable for tight crevices, gaskets and deposits.
- Monel 400 (63Ni-30Cu) has decades of proven seawater service: propeller shafts, valves, pump components and heat exchanger plates, with excellent resistance to fast-flowing seawater and biofouling resistance superior to stainless.
When to Step Up Further
For hot seawater, creviced geometries or critical duties, engineers move to Inconel 625 or super-austenitics like 254 SMO (PREN ≥ 42).
Cost Perspective
316L is the cheapest option but often the most expensive failure. Monel 400 costs more per kilo yet routinely outlives stainless equipment in marine service. See Monel 400 sheet & plate for stock.
Tailan Metal supplies nickel alloy sheet and plate in Inconel, Incoloy, Monel, Hastelloy and super-austenitic grades. For a quotation contact sales@tailanmetal.com or WhatsApp +86-18621377760.
Leave a Reply