Water treatment and desalination: 2205/2507 and crevice corrosion
Seawater has high chlorides, so 304 is generally unsuitable; 2205 serves general seawater systems and 2507 the harsher membrane or high-pressure sections.
Water treatment and desalination environments are high in chlorides, often oxygenated, with crevices and deposits that promote pitting and crevice corrosion.
Selection guidance:
• Normal fresh water/wastewater: assess 304/316L by chloride level and temperature.
• Seawater systems (cooling, pretreatment, low-pressure sections): duplex 2205 is common.
• High-pressure sections, critical RO membrane parts and severe crevices: 2507 or 6% Mo super-austenitic.
• Do not use 304 in direct seawater contact.
Design and process points:
1) Avoid crevices and trapped water; match gasket selection to flanges.
2) Pickle and passivate after welding; control the HAZ.
3) Evaluate cathodic protection/coatings combined with stainless for hydrogen embrittlement and galvanic effects.
4) Clean regularly to prevent biofouling and deposits.
Purchasing reminder: seawater projects often require third-party corrosion testing and material certificates; welding 2205/2507 requires procedure qualification and ferrite control.
Compiled by SteelWe editors and industry experts. For industry exchange only; not trading or investment advice. Cite the source when quoting.
