Material selection by PREN — super duplex, 254 SMO, 90/10 & 70/30 copper-nickel, titanium and GRP — plus cathodic protection for seawater intake structures.
Engineering Excellence for Marine Environments
Seawater’s chloride content (19,000–21,000 mg/L) with dissolved oxygen and biological activity drives pitting, crevice, galvanic and microbially-influenced corrosion. Reliable intakes are engineered around correct alloy selection (by pitting-resistance equivalent, PREN), velocity limits, galvanic compatibility and cathodic protection of submerged steel.
Matched to temperature, velocity and duty
| Material | PREN / Class | Typical Use |
|---|---|---|
| 316L stainless | ~24 | Temperate waters only; crevice-prone when warm |
| 254 SMO (6Mo) | ~43 | High-chloride pipework, pumps, fasteners |
| Super duplex 2507 | ~43 | Critical components, high strength & resistance |
| 90/10 copper-nickel | — | Screens & pipework; natural antifouling |
| 70/30 copper-nickel | — | Higher-velocity / more aggressive duty |
| Titanium Gr.2 | — | Heat exchangers, extreme/hot seawater |
| GRP / FRP | — | Large pipelines, basins, non-structural lines |
Beyond alloy choice
Aluminium / zinc anodes protect submerged steel structures and screens.
Controlled current for large structures with long design life and monitoring.
Glass-flake epoxy and marine linings on structural steel and concrete.
Dielectric breaks and compatible couples prevent dissimilar-metal attack.
Cu-Ni erosion-corrosion limits respected (typ. <3.5–4.5 m/s).
Biofilm and sulphate-reducing-bacteria control to limit microbial corrosion.
Continue across the seawater intake engineering series
Offshore submerged intakes and velocity-cap headworks for the largest duties.
Read MoreBeach wells and infiltration galleries for naturally filtered, low-SDI feed.
Read MoreChlorination, antifouling alloys and UV to keep intakes clear.
Read MoreMulti-stage screening for debris, seaweed and jellyfish.
Read More316(b) fish protection, velocity caps and low-entrainment design.
Read MoreThe full seawater intake hub — challenges, configurations and specifications.
Read MoreAlloy selection and corrosion engineering for marine duty.
Read MoreProtecting downstream RO membranes from fouling and oxidants.
Read MoreChlorination, antifouling alloys and UV to keep intakes clear.
Read MoreComplete SWRO desalination plant solutions.
Read MoreTalk to our marine engineering team about corrosion & materials and a complete, compliant intake package — survivable, low-fouling and built for decades of service.
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