Selecting alloys and non-metallics that survive warm, high-chloride seawater for the design life of a desalination intake — super-duplex, super-austenitic, titanium, GRP and HDPE, matched to duty, temperature and galvanic compatibility.
Desalination intakes handle warm, fully-aerated, high-chloride seawater — the classic environment for pitting and crevice corrosion of stainless steels and for galvanic attack between dissimilar metals. The wrong material does not fail gracefully: it pits, perforates and contaminates the feed, and a leak in a buried intake line is expensive to find and fix. Reynolds & Bauhm selects wetted materials on pitting resistance (PREN), temperature, mechanical duty and lifecycle cost, and engineers the galvanic and cathodic-protection details so the whole intake reaches its design life.
| Material | PREN / class | Where used |
|---|---|---|
| Super-duplex (S32750) | PREN > 40 | Pump casings, valves, high-duty pipework |
| Super-austenitic 6Mo (254 SMO) | PREN ~43 | Warm seawater, fasteners, heat-exchange |
| Titanium (Gr.2) | Effectively immune | Heat-exchanger plates, critical wetted parts |
| Cu-Ni 90/10 | Inherently anti-fouling | Pipework where biofouling resistance helps |
| GRP / GRE | Non-metallic | Large-bore intake pipe, tanks, sumps |
| HDPE | Non-metallic | Buried/marine intake pipelines |
| 316/316L stainless | PREN ~24 — avoid | Pits & crevice-corrodes in warm seawater |
Dissimilar metals in seawater drive galvanic corrosion of the less-noble part. We map the galvanic series across the system and isolate, match or protect accordingly.
Sacrificial anodes or impressed-current CP protect buried and submerged steel intake structures, screens and pump bowls where coatings alone are not enough.
Glass-flake epoxy and rubber linings protect carbon-steel structures cost-effectively, with detailing to avoid holidays and crevices at welds and flanges.
Critical pitting/crevice temperatures fall with chloride and rise with PREN. We select with margin above the warmest expected seawater, not the average.
Material choice and biofouling control are linked — Cu-Ni resists settlement, while smooth non-metallics ease cleaning. We design them together.
Biofouling ControlThe cheapest alloy is rarely the cheapest intake. We balance capital, maintenance and the cost of failure across the asset’s design life.
Give us the seawater temperature, chloride and the duty — we’ll produce a wetted-materials schedule and the galvanic/CP strategy for a full-design-life intake.
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