Material Selection for Seawater-Cooled Heat Exchangers: What Engineers Must Consider
Mr. Toey
Seawater is one of the most aggressive environments for heat exchanger systems. High levels of chlorides, biofouling, and oxygenated saline water create ideal conditions for pitting, crevice corrosion, and stress corrosion cracking (SCC).
Choosing the wrong material for tubes in seawater-cooled heat exchangers can lead to early failure, frequent maintenance, and high replacement costs.
In this article, we compare common stainless steel and alloy options for seawater service—and explain how DLSS Pipeline helps engineers select the right tube for long-term durability and cost efficiency.
Deposit-induced crevice corrosion from fouling or scaling
In tube systems, localized attack often initiates on the inner surface and accelerates quickly, especially in stagnant or low-velocity zones.
2. Material Options for Seawater Heat Exchangers
A. TP316L Stainless Steel
Affordable and widely available
Moderate resistance to chlorides
Not suitable for continuous seawater flow
Recommended only in indirect or brackish water systems
B. 904L Stainless Steel
High-alloy austenitic stainless steel
Better pitting and crevice resistance than 316L
Weldability and price are acceptable
Suitable for low-to-medium chlorides
C. Duplex 2205 (UNS S32205)
Higher strength and corrosion resistance than 316L
Good resistance to stress corrosion and pitting
Requires controlled welding and post-treatment
Used in offshore platforms, water-cooled gas systems
D. Super Duplex 2507 (UNS S32750)
Excellent chloride SCC and pitting resistance
High strength and good erosion resistance
Often used in marine condensers, FPSOs, and power plant intakes
E. Titanium Grade 2
Outstanding corrosion resistance in seawater
Excellent biofouling resistance
High cost, but extremely long service life
Ideal for desalination, naval systems, and offshore cooling
DLSS supplies 316L, 317L, 904L, 2205, and S32750 stainless steel tubes. Learn more at www.dlsspipeline.com
3. Performance Comparison
Material
Pitting Resistance (PREN)
Seawater Suitability
Typical Use Cases
TP316L
~25
Low (not continuous use)
HVAC, low-chloride water
904L
~35
Moderate
Heat exchangers in coastal plants
2205 Duplex
~35
High
Offshore cooling, ballast systems
2507 Super Duplex
~42–45
Very High
Subsea exchangers, marine condensers
Titanium Gr.2
>50
Excellent
Desalination, navy systems
4. Other Factors to Consider
Operating temperature: High temps (>60°C) increase SCC risk, especially in austenitic grades
Welding requirements: Duplex and titanium need specific welding expertise
Cost vs. lifecycle: Higher alloy cost often justified by reduced maintenance and replacement
Availability & lead time: DLSS maintains stable supply of seawater-grade stainless tubes
Frequently Asked Questions (FAQ)
Q1: Can I use 316L in seawater heat exchangers? Only in indirect contact or low-chloride applications. For direct seawater cooling, consider 2205 or higher-grade alloys.
Q2: How do I know if duplex is enough, or I need super duplex/titanium? Check chloride content, temperature, flow rate, and life expectancy. DLSS can help assess the correct material based on your process.
Q3: Can DLSS supply tubes with both corrosion and mechanical test certificates? Yes, all DLSS seawater-grade tubes are supplied with full EN 10204 3.1/3.2 certificates, including PMI, hydro test, and surface roughness inspection if needed.
Conclusion
In seawater-cooled systems, material selection is not optional—it’s a critical engineering decision. With aggressive chloride levels and long expected lifespans, choosing the right stainless or alloy tube prevents failure, reduces life-cycle cost, and protects equipment integrity.
DLSS Pipeline supports global projects with corrosion-resistant stainless steel and duplex tubes engineered for marine and offshore environments.
