Plate heat exchangers are among the most widely used pieces of equipment in industrial facilities.

They are compact, highly efficient, and easy to install and maintain.

However, if you visit enough factories, you'll often hear the same complaint:

"Why does our plate heat exchanger keep leaking?"

Whether it's water, oil, or process media, leaks create extra work for operators, increase maintenance costs, and can even interrupt production.

So what really causes plate heat exchanger leaks?

Is poor product quality always to blame, or are there other factors involved?

1. Worn or Aged Gaskets – The Most Common Cause of Leakage

The sealing performance of a plate heat exchanger depends primarily on its gaskets.

Like the rubber seal around a door, each gasket fits tightly around the edge of a plate to keep different fluids separated.

However, rubber components have a limited service life.

Continuous exposure to high temperatures or aggressive chemicals gradually causes the gasket to harden, age, and lose its elasticity.

Once the gasket can no longer maintain a proper seal, leakage becomes inevitable.

Some operating conditions place even greater stress on the gaskets.

For example:

• High-temperature water in power plants continuously exposes the gasket to temperatures above 100°C.
• Acidic and alkaline chemicals in chemical processing plants accelerate material degradation.
• Food processing facilities require frequent cleaning and sterilization, which also shortens gasket life.

Over time, the gasket behaves like a rubber band that has been stretched too many times-eventually, it can no longer perform its sealing function.

2. Improper Assembly Can Lead to Serious Leakage

A plate heat exchanger is assembled by stacking many plates together and compressing them evenly with tightening bolts.

Imagine stacking a deck of cards.

Every card must be perfectly aligned and compressed evenly from all sides.

If the tightening bolts are uneven or installed without following the correct procedure, one side may be over-compressed while the other remains loose.

This uneven pressure can damage the sealing line and create leakage paths.

A typical example comes from a beverage factory.

After replacing the gaskets, the maintenance team tightened the bolts based only on experience instead of using a calibrated torque wrench.

Within two weeks, the heat exchanger began leaking, resulting in an entire batch of beverages being discarded.

Even something as simple as improper bolt tightening can shut down an entire production line.

3. Damage to the Heat Transfer Plates

The heat transfer plates themselves are made from thin stainless steel, typically only 0.5 to 0.8 mm thick.

Although they are strong enough for normal operation, they remain vulnerable to long-term damage.

The two biggest threats are:

Corrosion

Acidic media, alkaline solutions, or fluids containing chloride ions can gradually create corrosion pits on the plate surface.

Erosion

Excessively high flow velocity can continuously wear the plates, much like sandpaper slowly grinding away a metal surface.

In many facilities, the damage begins as tiny pinholes that are almost impossible to detect.

Once a plate is perforated, however, fluid from the high-pressure side can leak into the low-pressure side.

This is more than a simple leak.

It can lead to cross-contamination between two process fluids that should never mix, potentially causing serious production failures.

During one inspection at an electroplating plant, several plates had developed small holes due to chloride corrosion.

Cleaning chemicals leaked into the circulating water system, contaminating tens of tons of water and causing losses worth millions.

4. Improper Operating Practices Often Cause More Problems Than the Equipment Itself

In many cases, leakage is not caused by equipment defects but by improper operation.

Common operating mistakes include:

• Frequent start-stop cycles, which repeatedly expand and contract both the plates and gaskets, leading to fatigue over time.
• Operating above the rated pressure. For example, forcing a unit designed for 1.0 MPa to operate at 1.4 MPa can overload the sealing system and cause immediate leakage.
• Using highly aggressive acids or alkalis during cleaning, which can accelerate corrosion and eventually perforate the plates.

To be honest, many leakage problems are not caused by poor equipment quality but by operating practices that do not follow recommended procedures.

5. How Can Plate Heat Exchanger Leaks Be Prevented?

When leakage occurs, replacing the entire heat exchanger is usually unnecessary.

In most cases, proper maintenance can solve the problem.

Here are several practical recommendations:

Replace gaskets on schedule

Do not wait until leakage occurs.

Under high-temperature or corrosive operating conditions, gasket replacement should typically be considered every 3–5 years, depending on service conditions.

Follow proper assembly procedures

Always tighten bolts with a calibrated torque wrench and follow the recommended diagonal tightening sequence to ensure even compression.

Monitor the condition of the plates

Perform regular inspections using methods such as eddy current testing or dye penetrant inspection to detect small defects before they become serious failures.

Improve operating practices

Reduce unnecessary start-stop cycles, avoid operating above the design pressure, and always use approved cleaning chemicals during maintenance.

Final Thoughts

Most plate heat exchanger leaks can be traced to four primary causes:

• Gasket aging
• Improper assembly
• Plate damage
• Poor operating practices

When leakage occurs, don't immediately assume the equipment is defective.

Instead, review how the unit has been installed, operated, and maintained.

In many industrial facilities, costly failures worth hundreds of thousands-or even millions-are often caused not by equipment design, but by preventable maintenance and operating issues.