Best Tube Materials for Shell and Tube Heat Exchangers

The best tube materials for shell-and-tube heat exchangers depend on fluid chemistry, temperature, velocity, and fouling risk. Cu-Ni 90/10 and 70/30 excel in natural seawater; aluminum brass (C68700) works in cleaner chloride waters; titanium (Grade 2) offers top corrosion/erosion resistance but at higher cost; 316L/duplex stainless steels suit many petrochemical services; and admiralty brass (C44300) fits low-chloride, non-sulfide waters. Following TEMA and AMPP guidelines ensures optimum performance. Admiralty Industries manufactures all these alloys to international standards and can help engineers match the right material to their exact marine or petrochemical application.

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 like TEMA provide design standards, while AMPP (formerly NACE) and the Copper Development Association (CDA) offer corrosion data and material usage guidance.

1. Define the service – cooling vs. condensing, seawater vs. process water, clean vs. fouling.

2. Check chemistry – chlorides, sulfides/H₂S, ammonia, sand/silt, biocides (chlorination).

3. Consider velocity – stay within each alloy’s design velocity to avoid impingement.

4. Match temperature & pressure – especially for stainless and titanium.

5. Balance lifecycle cost – capex vs. corrosion allowance, cleaning frequency, downtime.

Best for: Natural seawater cooling, desalination brine heaters/condensers, marine HVAC, moderate erosion risk.

Why it works: Cu-Ni forms protective films in aerated seawater and resists impingement/erosion better than brasses; 70/30 offers higher strength/velocity tolerance than 90/10. Design practice includes staying within recommended velocity limits to control erosion.

Watch-outs: Sulfide pollution (harbor water, stagnant zones) and strong ammonia can break down protective films; screening/filtration and chlorination control matter. 

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

Best for: Cleaner waters with lower chloride and low sulfide/ammonia contamination; power plant condensers and some industrial coolers.

Why it works: Aluminum brass improves on admiralty brass for chloride service and impingement resistance; both are used widely where waters are unpolluted and velocities are controlled.

Watch-outs: Ammonia or sulfides can cause rapid attack; not recommended for polluted seawater.

Use when: Water quality is known and controlled (river/lake intakes, closed-loop coolers) and lifecycle economics favor brasses over higher-cost alloys. Historical AMPP notes also document a shift from admiralty to Al-brass/Cu-Ni for tougher marine service.

Best for: Many petrochemical services, some brackish waters, and higher-temperature duties where Cu-based alloys may fall short.

Why it works: 316L can perform in aerated seawater for certain components; duplex/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 90/10 Cu-Ni as suitable in certain MED sections.

Watch-outs: Risk of chloride stress-corrosion cracking at higher temperatures; careful control of crevices and weld metallurgy is essential.

Best for: Highly aggressive chloride service, warm seawater, high-velocity conditions, and plants prioritizing maximum uptime.

Why it works: Outstanding resistance to pitting/crevice corrosion, erosion, and biofouling; often the lifecycle-cost winner in severe seawater service, despite high initial cost. 

Watch-outs: Cost and galling considerations; ensure appropriate waterbox/tubesheet pairing and avoid cross-metal galvanic traps.

In some services, non-metallic materials (rubbers, polymers, fiber-reinforced plastics) are used for components or as linings to decouple the tube ID from corrosive fluids—particularly when fouling or specific chemistries defeat metallic options. Consult AMPP’s non-metallic selection guidance for such cases.

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

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

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

• Typical picks: 316L/duplex for many hydrocarbon/lean-amine services; Cu-Ni or titanium on seawater side of condensers; Al-brass in clean cooling waters with low contaminant risk. Validate against expected H₂S, ammonia, and chlorides.

1) Fluid velocity & 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 similar velocity.

2) Oxygen & biocides

Cu-based alloys rely on stable oxide films in aerated water; in deaerated brines (desalination) behavior changes, and design must reflect that. Chlorination helps control biofouling but should be managed to avoid over- or under-dosing.

3) Contaminants (sulfides, ammonia)

Trace sulfides/H₂S or ammonia can depassivate copper alloys and trigger rapid attack. If there’s any risk from industrial discharges, harbors, or stagnation, specify titanium or appropriate stainless/duplex or add upstream treatment.

4) Cleaning strategy

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

Selecting the best tube material for a shell-and-tube heat exchanger isn’t just a design decision — it’s a long-term operational commitment. The right alloy balances corrosion resistance, thermal performance, cost, and ease of maintenance, ensuring the exchanger delivers reliable service for decades.

Whether it’s Cu-Ni for proven seawater resistance, aluminum brass for clean-water economics, stainless and duplex steels for petrochemical versatility, or titanium for maximum protection in harsh conditions, the key is matching the material to the exact service environment.

By working with an experienced supplier who understands both the engineering and the application, you can reduce unplanned outages, lower total lifecycle costs, and keep your operation running at peak efficiency.

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/.