Best Tube Materials for Shell and Tube Heat Exchangers

• Copper-nickel 90/10 (C70600) and 70/30 (C71500) are the proven choice for natural seawater cooling and desalination brine sections.

• Aluminum brass (C68700) and admiralty brass (C44300) suit clean, low-chloride waters with no sulfide or ammonia contamination.

• 316L and duplex stainless steels (2205) cover most petrochemical and higher-temperature services.

• Titanium Grade 2 wins on lifecycle cost in polluted or high-velocity seawater, despite the highest initial price.

• Fluid chemistry, velocity, temperature, and cleaning strategy decide the right alloy, not price alone.

The best tube materials for shell and tube heat exchangers are copper-nickel 90/10 and 70/30 for natural seawater, aluminum brass and admiralty brass for clean low-chloride waters, 316L and duplex stainless steels for petrochemical services, and titanium Grade 2 for polluted or high-velocity seawater. The right choice depends on fluid chemistry, operating temperature, design velocity, and fouling risk, following TEMA design standards and AMPP corrosion guidance.

Tube failure is one of the most common causes of heat exchanger downtime. Choosing the wrong alloy can trigger impingement erosion, pitting, stress-corrosion cracking, or biofouling, especially in marine and petrochemical environments where chloride, sulfide, or ammonia contaminants are common.

Industry bodies set the reference framework. TEMA provides design standards, while AMPP (formerly NACE) and the Copper Development Association (CDA) publish corrosion data and material usage guidance for heat exchanger tubes across service conditions.

Engineers select tube materials by working through five checks in order: service type, water chemistry, velocity, temperature and pressure, and lifecycle cost.

• Define the service: cooling vs. condensing, seawater vs. process water, clean vs. fouling.

• Check chemistry: chlorides, sulfides/H₂S, ammonia, sand and silt, biocides (chlorination regime).

• Consider velocity: stay within each alloy’s design velocity to avoid impingement attack.

• Match temperature and pressure: critical for stainless steels and titanium.

• Balance lifecycle cost: capex vs. corrosion allowance, cleaning frequency, and downtime.

A structured walkthrough of these steps is available in our guide on how to select the right heat exchanger tube material.

Five material families cover almost every shell and tube application: copper-nickels, brasses, stainless steels, titanium, and non-metallic alternatives for niche cases.

1) Copper-nickel 90/10 (C70600) and 70/30 (C71500)

Copper-nickel is the default choice for natural seawater cooling, desalination brine heaters and condensers, marine HVAC, and services with moderate erosion risk.

Cu-Ni forms protective films in aerated seawater and resists impingement erosion better than brasses. Cu-Ni 70/30 (C71500) offers higher strength and velocity tolerance than Cu-Ni 90/10 (C70600). Design practice keeps velocities within CDA recommended limits to control erosion.

Watch-outs: sulfide pollution (harbor water, stagnant zones) and strong ammonia break down the protective film. Screening, filtration, and chlorination control matter. For alloy specifications, grades, and standards, see our guide to copper-nickel tubes.

Use Cu-Ni when you need proven, cost-effective seawater performance without jumping to titanium, especially in MSF/MED desalination and shipboard systems.

2) Aluminum brass (C68700) and admiralty brass (C44300)

Brasses fit cleaner waters with lower chloride and low sulfide or ammonia contamination, such as power plant condensers and industrial coolers on river or lake intakes.

Aluminum brass (C68700) improves on admiralty brass for chloride service and impingement resistance. Admiralty brass (C44300) remains widely used where waters are unpolluted and velocities are controlled.

Watch-outs: ammonia or sulfides cause rapid attack. Brasses are not recommended for polluted seawater. Historical AMPP notes document the industry shift from admiralty brass to aluminum brass and Cu-Ni for tougher marine service.

3) Austenitic and duplex stainless steels (316L, 2205)

Stainless steels cover many petrochemical services, some brackish waters, and higher-temperature duties where copper-based alloys fall short.

316L performs in aerated seawater for certain components, and duplex or super duplex grades extend chloride resistance and strength. Selection depends on pitting resistance equivalent (PREN), temperature, and chloride load. AMPP desalination guidance frequently cites 316L and Cu-Ni 90/10 as suitable in certain MED sections.

Watch-outs: chloride stress-corrosion cracking risk rises with temperature. Crevice control and weld metallurgy are essential.

4) Titanium (commercially pure, Grade 2)

Titanium Grade 2 handles highly aggressive chloride service, warm seawater, high-velocity conditions, and plants that prioritize maximum uptime.

Titanium offers outstanding resistance to pitting, crevice corrosion, erosion, and biofouling. It is often the lifecycle-cost winner in severe seawater service despite the high initial cost.

Watch-outs: cost and galling considerations. Pair the tubes with an appropriate waterbox and tubesheet to avoid galvanic traps between dissimilar metals.

5) Non-metallic liners and alternatives

Non-metallic materials (rubbers, polymers, fiber-reinforced plastics) serve niche cases as components or linings that decouple the tube ID from corrosive fluids, particularly when fouling or specific chemistries defeat metallic options. AMPP publishes non-metallic selection guidance for these cases.

Cu-Ni alloys lead in natural seawater, Cu-Ni and 316L split desalination duties by section, and stainless or duplex grades dominate petrochemical cooling. 

Seawater (intake, once-through, coastal plants)

Good starting points: Cu-Ni 90/10 or 70/30. Upgrade to titanium for high temperature, high velocity, or polluted seawater.

Design notes: respect velocity limits to avoid impingement, and manage chlorination and screening to control biofouling and solids. CDA publishes accepted design velocities for condenser tubing by alloy.

Desalination (MSF/MED)

Typical picks: Cu-Ni 90/10 in deaerated brine sections, 316L or higher alloys in aerated seawater sections, titanium where lifecycle cost dictates.

Petrochemical and refinery cooling

Typical picks: 316L or duplex for many hydrocarbon and lean-amine services, Cu-Ni or titanium on the seawater side of condensers, aluminum brass in clean cooling waters with low contaminant risk.

Validate every selection against expected H₂S, ammonia, and chloride levels.

The more corrosive or fouling fluid normally goes on the tube side. Tube bores are easier to clean mechanically, and upgrading the tube alloy is cheaper than upgrading the entire shell. Cooling water, seawater, and brines therefore usually run inside the tubes, while the cleaner process fluid runs on the shell side.

Four variables drive most tube failures: fluid velocity, oxygen and biocide levels, contaminants, and the cleaning strategy applied over the exchanger’s life.

1) Fluid velocity and solids

Erosion-corrosion accelerates above alloy-specific velocities, especially with entrained sand or silt. Follow CDA velocity guidance and TEMA good practice, use adequate screening, and maintain flow distribution so each tube sees a similar velocity.

2) Oxygen and biocides

Copper-based alloys rely on stable oxide films in aerated water. In deaerated brines (desalination) the corrosion behavior changes, and the design must reflect that. Chlorination helps control biofouling but needs careful dosing control.

3) Contaminants (sulfides, ammonia)

Trace sulfides, H₂S, or ammonia can depassivate copper alloys and trigger rapid attack. If industrial discharges, harbors, or stagnation create any contamination risk, specify titanium or an appropriate stainless or duplex grade, or add upstream treatment.

4) Cleaning strategy

Mechanical cleaning and chemical descaling must align with alloy limits. For Cu-Ni and brasses, avoid aggressive chemistries that strip protective films. For stainless and titanium, prevent abrasive damage that initiates pitting under deposits. AMPP covers fouling and galvanic control in tube and shell assemblies.

The right alloy balances corrosion resistance, thermal performance, cost, and ease of maintenance, and keeps the exchanger in reliable service for decades. Copper’s thermal conductivity advantage explains why copper alloys remain the reference for water-cooled services; the reasons are covered in why copper is used in heat exchangers.

Working with an experienced supplier who understands both the engineering and the application reduces unplanned outages and lowers total lifecycle cost. Material selection made on price alone is the most expensive mistake a project can make.

Admiralty Industries supplies tube materials manufactured to international standards, with full mill certification and custom dimensions to fit your design. Our experts can help you match the right alloy to your exact marine, petrochemical, or industrial cooling application, ensuring compliance with TEMA and ASTM specifications.

Contact our technical team to discuss your project requirements or request a detailed quotation.

Copper Development Association. Seawater System Design: Heat Exchangers and Piping. Copper Development Association Inc., 2017, https://www.copper.org/applications/marine/cuni/applications/seawater_system_design/heat_exchangers_piping/.

Tubular Exchanger Manufacturers Association. TEMA Standards. TEMA, https://tema.org/.

Association for Materials Protection and Performance (AMPP). Multiple Effect Distillation (MED). In Corrosion Management and Control in Desalination, AMPP, Chapter 7, https://content.ampp.org/books/book/19/chapter/2214600/.