UK HQ Your time

Material Selection

Engineering-grade material selection based on your specific wastewater chemistry and duty conditions.

Wastewater Analysis

Comprehensive water chemistry analysis identifies chlorides, sulphides, pH extremes, and oxidising agents that drive corrosion. Material selection is based on data, not guesswork.

Corrosion Modelling

We apply ISO 9223 and ASTM G102 corrosion rate models to predict service life for each candidate material under your specific operating temperature and chemistry conditions.

Life-Cycle Costing

Material selection balances initial cost against replacement frequency and downtime. Duplex or super duplex may cost more upfront but deliver 3x the service life in aggressive waters.

Regulatory Compliance

Food-grade applications require FDA-compliant materials. Pharmaceutical systems need ASME BPE certification. We specify materials that meet your sector requirements from day one.

Coating & Lining

For mild-to-moderate corrosivity, protective coatings and rubber linings on carbon steel offer efficient alternatives to solid alloy construction with proven field performance.

Mill Certification

All materials supplied with EN 10204 3.1 mill certificates verifying chemical composition, mechanical properties, and heat treatment. Full traceability from melt to finished equipment.

Material Options

From standard stainless to exotic alloys for the most aggressive industrial wastewaters.

SS304

Economical austenitic stainless for mild municipal and food applications where chloride levels are below 200 mg/L and pH is neutral.

SS316L

Standard industrial grade with 2-3% molybdenum for improved pitting resistance. Suitable for most industrial effluents with moderate chloride content.

Duplex 2205

50/50 ferrite-austenitic structure delivers superior chloride stress corrosion cracking resistance. Ideal for marine, coastal, and high-salinity applications.

Super Duplex 2507

PREN > 40 for extreme chloride environments, sour gas, and high-temperature process waters. Service life exceeds 25 years in aggressive duty.

Hastelloy C-276

Nickel-molybdenum alloy for highly oxidising chemistries, strong acids, and halide environments where stainless steels fail rapidly.

Titanium Grade 2

Exceptional corrosion resistance in chloride, hypochlorite, and seawater. Used for high-purity pharmaceutical and offshore applications.

Pitting Resistance, Corrosion Rates & Coating Specifications

Pitting Resistance Equivalent Number (PREN)

PREN is the primary screening tool for pitting and crevice corrosion resistance in chloride environments. We calculate PREN using the ASTM-standard formula:

PREN = %Cr + 3.3×(%Mo + 0.5×%W) + 16×%N

For conservative design, we require PREN ≥ 0.6 × chloride concentration (mg/L) for temperatures >30 °C. For seawater (~19,000 mg/L Cl⁻) at ambient temperature, minimum PREN 35 is recommended.

AlloyPRENMax Cl⁻ (mg/L) at 40 °CRelative Cost Index
SS304 (1.4301)18–2050–1001.0
SS316L (1.4404)23–26200–5001.3
Duplex 2205 (1.4462)34–363,000–5,0001.8
Super Duplex 2507 (1.4410)42–4510,000–15,0002.6
SS254SMO (1.4547)43–4610,000–20,0003.0
Titanium Gr.2Immune*Unlimited4.5

*Titanium is immune to pitting in natural waters; susceptibility to hydriding limits temperature to <80 °C in alkaline conditions.

Protective Coatings & Linings

When solid alloy construction is uneconomical, protective coatings on carbon steel offer a efficient alternative:

SystemThicknessTemp. LimitBest For
Epoxy phenolic (2-coat)250–400 μm80 °CMild acids, potable water
Glass flake vinyl ester1,000–1,500 μm90 °CStrong acids, chlorinated water
PTFE / ECTFE (Halar) lining2–3 mm120 °C Aggressive chemicals, high purity
Natural rubber (NR) lining3–5 mm70 °CAbrasive slurry, mild acids
Chlorobutyl rubber (CBR)3–5 mm85 °CHypochlorite, oxidising media
Thermal spray aluminium (TSA)200–300 μm500 °CAtmospheric corrosion, splash zone

Coating selection follows ISO 12944 for corrosivity categories (C1–C5-I/M). Surface preparation to Sa 2½ (ISO 8501-1) with a profile of 50–75 μm is mandatory for high-performance coatings. Holiday detection (spark test at 5 kV/mm) is performed on every lined vessel.

Corrosion Allowance & Remnant Life Calculation

The design corrosion allowance is calculated from predicted corrosion rate and design life: CA = CR × tdesign + CAmargin, where CR is corrosion rate (mm/year) from ISO 9223 or ASTM G31 immersion testing, tdesign is the required service life (typically 20–25 years for water treatment infrastructure), and CAmargin is a 1–2 mm contingency for unexpected upset conditions. Remnant life during in-service inspection is estimated by: trem = (tmeasured – tmin) / CR, where tmeasured is the minimum remaining wall thickness from ultrasonic testing and tmin is the code-minimum wall (e.g., MAWP calculation per ASME VIII UG-27). Inspection intervals are set to ensure trem > 2× the inspection period at each survey.

Quality Assurance

Rigorous inspection and verification at every stage from raw material to finished equipment.

Incoming Inspection

All raw materials are inspected on arrival for dimensional accuracy, surface finish, and certificate compliance. Spectrometric analysis confirms alloy composition matches specification.

Welding Procedures

WPS and PQR documentation for every weld procedure. Welder qualifications to EN ISO 9606. In-process visual inspection and dye penetrant testing on critical joints.

Heat Treatment

Solution annealing and passivation restore corrosion resistance after welding. Furnace charts and temperature records are included in the quality dossier.

Pressure Testing

Hydrostatic pressure testing to 1.5x design pressure verifies weld integrity and mechanical strength. Test certificates are provided for every pressure vessel.

Dimensional Verification

CMM and laser measurement confirm fabrication tolerances. Critical dimensions for nozzle locations, flange bolt patterns, and interface points are verified against GA drawings.

Documentation Package

Complete quality dossier including material certificates, weld maps, NDT reports, pressure test records, and surface finish measurements. Available in hard copy and PDF.

Related Pages

Bespoke Automation

Custom automation and SCADA integration for critical water treatment processes plants.

View Page

Bespoke Custom Engineering

Our custom engineering team is involved in designing water treatment equipment to your exact specifications.

View Page

Bespoke Performance Targets

We design bespoke water treatment systems with guaranteed performance targets.

View Page

Bespoke Pilot Testing

De-risk your capital investment with on-site pilot testing.

View Page

Bespoke Process Integration

Seamlessly integrate new water treatment equipment with your existing infrastructure.

View Page

Bespoke Space Constraints

Compact and containerised water treatment plants for space-limited sites.

View Page

Bespoke Engineering Capability

Every water treatment challenge is unique. Our bespoke engineering team designs, fabricates, and commissions custom equipment and systems that standard products cannot address. From exotic material selection to extreme duty specifications, space-constrained layouts, and integration with legacy control systems, we deliver solutions that work in your specific operational context.

Custom Design

3D CAD modelling and CFD simulation validate performance before fabrication commences.

In-House Fabrication

SS304, SS316L, duplex, and exotic alloy welding and machining in our European workshops.

Legacy Integration

Control systems communicate with your existing SCADA, DCS, and PLC infrastructure.

Full Documentation

Complete design dossier, HAZOP, FAT/SAT protocols, and O&M manuals provided.

Bespoke Project Workflow

1. Needs Assessment

Site survey, water analysis, and process requirement definition with your engineers.

2. Concept Design

Process flow diagram, P&ID, and 3D layout with performance guarantees and budget estimate.

3. Detailed Engineering

Mechanical, electrical, and control design with material specifications and vendor selection.

4. Fabrication

Workshop construction with QA/QC inspection, weld records, and pressure testing.

5. Delivery & Installation

Logistics, cranage, mechanical installation, and pipework connection by our teams.

6. Commissioning

FAT, SAT, performance trials, operator training, and handover documentation.

Materials & Construction Options

SS316L

Standard corrosion-resistant stainless for municipal, food, and general industrial applications.

Duplex 2205

Superior chloride resistance for marine, offshore, and high-salinity process waters.

Super Duplex

Maximum corrosion resistance for extreme chloride, sour gas, and high-temperature duties.

Exotic Alloys

Hastelloy, Inconel, and titanium for aggressive chemistries and ultra-high purity requirements.

Need help with speciality materials & coatings?

Our experts can design a system tailored to your specific requirements.

Industries We Serve

Our expertise spans multiple industries with sector-specific water treatment solutions.