Foam vs Fouling: What Actually Drives Outage Duration?

Responsible gas turbine compressor maintenance includes regular, effective cleaning. But how often do operators stop to evaluate whether those cleaning cycles are actually as efficient as they could be?

Every hour a gas turbine is offline impacts productivity, output, and operating costs. That’s why understanding what truly drives cleaning outage time is critical, especially if there are opportunities to reduce downtime without compromising cleaning performance.

What determines outage duration?

During off-line cleaning, the gas turbine compressor is shut down and isolated.

After the soak wash:

• The cleaning solution is drained
• Samples are analyzed
• Additional wash cycles are performed if needed
• The gas turbine compressor is thoroughly rinsed before returning to service

Most operators assume that the outage duration is driven entirely by how heavily fouled the compressor is.

But fouling is only part of the equation.

In reality, total outage time is typically determined by two factors:

• Severity of the gas turbine compressor fouling
• Foam levels and required rinse time

While both matter, foam-related rinse time is often underestimated.

Why foam has a major impact on downtime

Before a turbine can safely return online, excess foam must be completely rinsed from the compressor.

This means rinse duration can significantly extend total outage time, even after fouling has already been removed.

In many cases, operators spend more time rinsing away foam than actually cleaning the gas turbine compressor itself.

Understanding this distinction is one of the first steps toward reducing unnecessary downtime.

Cleaning heavily fouled compressors

A heavily fouled gas turbine compressor requires more energy to produce the same output.

As deposits build up:

• Internal airflow volume decreases
• Compressor efficiency drops
• Fuel consumption increases
• The risk of operational issues rises

When severe fouling is present during an offline wash, longer soak and rinse cycles are often required to allow cleaning chemicals enough contact time to penetrate and remove deposits effectively.

Foam plays an important role in this process because it:

• Increases the surface area covered by the cleaning chemicals
• Extends chemical dwell time
• Improves foulant penetration

However, excessive foam creates a different problem: it takes much longer to rinse completely from the gas turbine compressor.

The key is finding the right balance, enough foam for effective cleaning, but not so much that rinse times become excessive.

How to reduce outage time

The better alternative is to attempt fouling prevention and carefully choose an effective gas turbine compressor cleaning chemical which produces appropriate levels of foam for a thorough clean without requiring excessive rinsing.

Some operators attempt to reduce rinse time by double-diluting their cleaning chemicals.

While this may reduce foam production, it also reduces cleaning effectiveness and can create larger problems over time.

Short-term downtime may improve, but the tradeoff often includes:

• Reduced cleaning performance
• Faster foulant buildup
• More frequent offline washes
• Increased operating costs
• Potentially shorter equipment life

In other words, getting back online faster doesn’t necessarily mean the gas turbine compressor is actually cleaner.

Examples of how foam affects rinse time

Many operators report exceeding minimum rinse pulse requirements simply to remove excess foam. This highlights how rinse duration is often driven more by foam management than by fouling severity alone.

Switching to a properly engineered low-foam detergent can significantly reduce rinse cycles and overall outage duration while still maintaining cleaning effectiveness.

Get in touch

Reducing offline gas turbine compressor cleaning outage time starts with understanding what’s actually causing the delay.

While severe fouling certainly increases cleaning requirements, foam levels and rinse duration are often the hidden drivers of extended downtime.

Choosing the right cleaning chemistry can help operators:

• Reduce rinse times
• Improve cleaning consistency
• Minimize downtime
• Maintain compressor efficiency
• Lower long-term operating costs

Rochem’s FYREWASH® product range is specifically designed to target gas turbine compressor foulants while controlling foam production, helping operators achieve effective cleaning without excessive rinse requirements.

With a range of gas turbine compressor cleaning solutions available, the Rochem team can help identify the right approach for your operation and maintenance strategy. Contact us to find out more.

References: all data supplied by Rochem.