Preventing Metal Corrosion During Industrial Cleaning

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Manufacturing facilities often face the problem of metal surface corrosion during cleaning, whether it involves machine parts, tools, or production lines. Aggressive cleaning agents, unsuitable pH levels, or prolonged exposure can accelerate material degradation, leading to higher maintenance and component replacement costs. The solution lies not only in selecting the right cleaning agent but also in optimizing process parameters such as temperature, concentration, and exposure time. In this article, we will explore specific steps to minimize corrosion risks and ensure effective cleaning without damaging metals.

Why Corrosion Issues Occur: Chemical and Physical Causes

Corrosion damage to metal surfaces during industrial cleaning is a common problem that can lead to financial losses, production downtime, and reduced quality of final products. The main cause is a combination of aggressive components in cleaning agents, unsuitable working conditions, and insufficient material protection. Typical culprits include strong inorganic acids (e.g., hydrochloric or sulfuric acid), which effectively remove impurities but simultaneously disrupt the passive layer on metal surfaces. Alkaline cleaning agents with high pH can be equally problematic, especially if they contain chlorides or other halides that accelerate localized corrosion.

Another factor is temperature and exposure time. At elevated temperatures (above 50 °C), corrosion reactions accelerate, even with less aggressive cleaning agents. Mechanical stress also plays an important role—for example, during pressure cleaning or ultrasonic baths—which can damage protective coatings or speed up the diffusion of corrosive agents into the metal structure. Therefore, the correct solution requires first identifying the specific corrosion mechanism (e.g., uniform, pitting, crevice) and the conditions under which it occurs.

Selecting the Right Cleaning Agent: Balancing Efficiency and Compatibility

The key to corrosion prevention is choosing a cleaning agent that effectively removes impurities while minimizing the risk of damage to metal surfaces. For sensitive materials such as aluminum, copper, or high-nickel alloys, neutral or mildly alkaline cleaning agents with a pH range of 7–10 are recommended. These products often contain corrosion inhibitors that form a temporary protective layer on the metal surface. Inhibitors based on amines, phosphonates, or organic acids (e.g., citric acid) are commonly used and effective even at low concentrations (0.1–2%).

For heavily soiled surfaces where acidic or strongly alkaline agents must be used, it is essential to adhere to precise dosing and exposure time. For example, acidic cleaners based on phosphoric acid are less aggressive than hydrochloric acid and simultaneously promote the formation of a protective phosphate layer. It is also important to consider compatibility with subsequent processes, such as painting or galvanizing—residues of certain inhibitors may negatively affect coating adhesion or the quality of the plating. It is always advisable to conduct laboratory compatibility tests before implementation in production.

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Optimizing the cleaning process: Temperature, time, and technological parameters

Even the gentlest cleaning agent can cause corrosion damage if the cleaning process is not set up correctly. Temperature is one of the most critical parameters – too high accelerates chemical reactions, including undesirable corrosion, while too low reduces cleaning efficiency. For most industrial applications, a temperature range of 40–60 °C is recommended, whereas for sensitive materials (e.g. aluminium), the temperature should not exceed 50 °C. For acidic cleaning agents, it is advisable to work at lower temperatures (30–40 °C) to minimise the risk of hydrogen embrittlement in high-strength steels.

Exposure time should be as short as possible but sufficient to achieve the required cleanliness. For manual cleaning, a maximum of 10–15 minutes is recommended, while for automated lines, the duration can be optimised based on test results. It is also important to ensure even coverage of the surface with the cleaning agent and prevent it from drying out, which can lead to localised concentration increases and thus corrosion attack. In the case of ultrasonic cleaning, attention must be paid to frequency and power to avoid cavitation, which can damage the metal surface.

Practical Approach to Solutions: From Diagnosis to Preventive Measures

The first step in addressing corrosion issues is thorough diagnostics. The operator should identify where and under what conditions corrosion occurs and take samples for laboratory analysis. This can reveal the presence of corrosion products (e.g. iron oxides, aluminium hydroxides) or aggressive ions (chlorides, sulphates) in the cleaning agent. Based on the results, the composition of the cleaning agent can be adjusted, for example by adding corrosion inhibitors or reducing the concentration of aggressive components. In some cases, it may be necessary to change the entire cleaning process, such as switching from acidic to alkaline cleaning or introducing a rinse with low-salt water.

Preventive measures include regular checks of cleaning agent quality, operator training, and equipment maintenance. It is also important to monitor the parameters of water used for dilution or rinsing—high hardness or chloride content can exacerbate corrosion issues. For long-term protection, temporary protective coatings (e.g., wax- or oil-based) can be applied, or permanent solutions such as surface passivation can be chosen. In any case, it is crucial to document all changes and continuously evaluate their effectiveness to prevent recurring problems.

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The Role of Corrosion Inhibitors in Industrial Cleaning Agents

Corrosion inhibitors are a key component of many industrial cleaning agents, especially when working with metal surfaces. These substances form a protective layer on the metal surface, preventing direct contact with aggressive components of the cleaning agent or the surrounding environment. Inhibitors work on the principle of chemical adsorption or the formation of a passivation layer, which slows down the electrochemical reactions leading to corrosion. Typically, organic compounds (e.g., amines, carboxylic acids) or inorganic salts (phosphates, nitrites) are used, which are compatible with common surfactants and chelating agents in cleaning formulations.

When selecting an inhibitor, it is necessary to consider the type of metal, the chemical composition of the cleaning agent, and the process conditions (temperature, pH, mechanical stress). For example, nitrogen-based inhibitors are often used for steel surfaces, while organophosphates are more suitable for aluminum or copper. The dosage of the inhibitor usually ranges from 0.1–2% of the total volume of the cleaning agent, with the optimal concentration verified by standard corrosion tests according to applicable standards. Inhibitors can be added directly to the cleaning agent concentrate or applied as a separate phase in the cleaning process.

Diagnosing Corrosion Damage: How to Identify the Cause and Extent of the Problem

The first step toward effectively addressing corrosion problems is thorough diagnostics. Start with a visual inspection of the affected surfaces—look for color changes, pits, cracks, or deposits of corrosion products. For a deeper analysis, use microscopic methods to reveal the microstructure of the damage and help determine the type of corrosion (e.g., uniform, pitting, crevice, or galvanic). It is also important to map the conditions under which the corrosion occurred: temperature, humidity, presence of aggressive substances (chlorides, acids, alkalis), and mechanical stress.

For laboratory analysis, take samples of corrosion products and perform chemical tests, such as X-ray diffraction or spectroscopy, to identify specific compounds. Simultaneously, test the compatibility of the cleaning agent with the material using standard corrosion tests, such as salt spray testing or immersion tests. These methods will provide quantitative data on corrosion rates and help determine whether the issue is caused by the cleaning agent itself, process technological parameters, or a combination of both factors.

Preventive Measures and Long-Term Protection of Metal Surfaces

After resolving an acute corrosion issue, it is essential to implement preventive measures to minimize the risk of recurrence. The foundation is regular maintenance and monitoring of the cleaning process—track pH, temperature, and concentration of the cleaning agent to prevent deviations from optimal values. It is also important to regularly inspect the condition of metal components and replace or repair them in a timely manner. For long-term protection, temporary protective coatings such as preservative oils or waxes can be used to create a barrier against moisture and aggressive substances.

Another effective measure is the implementation of corrosion-resistant materials or surface treatments, such as galvanizing, anodizing, or the application of polymer coatings. If changing the material is not possible, consider modifying the technological process—for example, reducing the cleaning temperature, shortening exposure time, or using less aggressive cleaning agents. Do not forget to train employees who work with the cleaning process so they can recognize early signs of corrosion damage and respond appropriately.

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