Common Heat Exchanger Tube Failure Modes: Corrosion, Leaks, and Material Selection

Heat exchanger tube failures are most commonly caused by corrosion, erosion, and incorrect material selection. Understanding failure modes such as dezincification, galvanic corrosion, and wall thinning helps engineers and buyers choose the right tube material and prevent leaks, unplanned shutdowns, and costly replacements.

Heat exchanger tubes operate at the intersection of pressure, temperature, fluid chemistry, and velocity. When failures occur, they rarely result from a single factor. Instead, they are usually the consequence of material–environment mismatch, combined with operating conditions that accelerate degradation over time.

Understanding how and why heat exchanger tubes fail is essential for engineers, maintenance teams, and procurement professionals who want to reduce downtime, extend equipment life, and avoid premature replacement.

This article examines the most common heat exchanger tube failure modes and explains how correct material selection plays a central role in preventing them.

Tube failures are not random events. They are predictable outcomes of design and specification choices made early in a project.

The most common contributing factors include:

• aggressive or poorly controlled fluid chemistry

• high flow velocity and turbulence

• elevated temperatures and thermal cycling

• mixed metallurgy between tubes and tubesheets

• insufficient inspection or testing requirements

When tube material properties do not align with these conditions, degradation mechanisms begin to act long before visible leaks appear.

Corrosion is the dominant cause of tube failure across power generation, marine, refinery, and desalination systems.

It occurs when tube material reacts chemically or electrochemically with the surrounding fluid or deposits on the tube surface. Over time, this leads to wall thinning, loss of mechanical strength, and eventual leakage.

Different alloys resist corrosion in different ways, which is why generic material selection often leads to poor long-term performance.

Erosion-corrosion is a combined mechanical and chemical failure mechanism.

High fluid velocity, especially when carrying suspended solids or air bubbles, strips away protective oxide layers from the tube surface. Once exposed, the base metal corrodes rapidly.

This failure mode is common in:

• cooling water systems

• condensers

• high-flow heat exchangers

Materials with insufficient erosion resistance will show localized thinning, usually at tube inlets or areas of flow disturbance.

Dezincification is a selective corrosion mechanism that affects certain brass alloys.

In aggressive or stagnant water conditions, zinc is preferentially leached from the alloy, leaving behind a weakened, porous copper-rich structure. Although tubes may appear intact externally, their mechanical strength is severely reduced.

This phenomenon is particularly relevant when:

• standard brass is used instead of inhibited alloys

• water chemistry is poorly controlled

• service involves warm or slightly acidic water

Correct alloy selection is critical to prevent this silent but destructive failure mode.

Galvanic corrosion occurs when two dissimilar metals are electrically connected in the presence of an electrolyte.

In heat exchangers, this often happens between:

• tubes and tubesheets

• tubes and tube supports

• repairs made with incompatible materials

The less noble metal corrodes preferentially, leading to accelerated attack at contact points. Even alloys with good standalone corrosion resistance can fail quickly if paired incorrectly.

Tube leaks are usually the final symptom, not the root cause.

They result from progressive wall loss caused by corrosion, erosion, or localized attack under deposits. By the time leaks are detected, significant material degradation has already occurred.

Early-stage wall thinning often goes unnoticed without proper inspection methods, making material selection and testing requirements even more important.

Choosing the right tube material is the most effective way to mitigate failure risk.

Material selection should be based on:

• fluid composition

• operating temperature

• velocity and turbulence

• expected service life

• compatibility with adjoining components

Below are typical material strategies used to prevent common failure modes.

Admiralty brass alloys are widely used in cooling water and condenser applications due to their balanced combination of strength, thermal conductivity, and corrosion resistance.

When properly specified, inhibited admiralty brass offers good resistance to general corrosion and dezincification in controlled water conditions.

Aluminum brass provides improved resistance to erosion-corrosion and biofouling compared to standard brasses.

Its protective aluminum oxide film enhances performance in higher-velocity systems and moderately aggressive waters, making it a frequent choice for power plants and large condensers.

Copper-nickel alloys are specifically engineered for seawater service.

Their excellent resistance to biofouling, chloride-induced corrosion, and erosion makes them the preferred solution in marine and desalination environments where other alloys experience rapid degradation.

Material choice here directly determines service life.

Many tube failures originate from decisions driven by initial cost rather than operating reality.

Using a lower-cost alloy in an aggressive environment may reduce upfront expenditure, but it often results in:

• shortened service life

• frequent maintenance

• unplanned shutdowns

• higher lifecycle cost

Material selection should therefore be treated as a risk-management decision, not a commodity purchase.

To reduce failure risk, engineers and buyers should follow these principles:

• match tube alloy to fluid chemistry and temperature

• control flow velocity to avoid erosion

• avoid mixed metallurgy without proper isolation

• specify inspection methods such as eddy current testing

• require traceability and certification for critical services

These steps significantly extend tube life and improve system reliability.

Heat exchanger tube failures are rarely unavoidable. In most cases, they result from predictable interactions between material properties and operating conditions.

By understanding common failure modes and selecting tube materials accordingly, engineers and procurement teams can prevent corrosion, minimize leaks, and avoid costly downtime.

If you are evaluating tube materials for a critical heat exchanger application, working with a supplier that understands both materials and operating environments is essential. Contact Admiralty Industries to discuss material selection strategies tailored to your system requirements.

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