Clean-in-Place systems are central to maintaining hygiene across modern hygienic processing environments. Industries such as food, beverage, dairy and pharmaceutical manufacturing rely heavily on consistent, validated cleaning routines to ensure product quality and prevent contamination. Using the correct CIP chemicals is a critical part of that process. These chemicals allow complex equipment, pipes and vessels to be cleaned thoroughly without the need for disassembly, helping operators achieve effective results while reducing downtime and labour requirements.
At ALLMECH ENGINEERING LTD, we recognise that CIP systems depend not only on well-designed equipment but also on the correct chemical selection and cleaning methodology. Understanding the role each chemical plays within the CIP cycle helps ensure safe operation, optimised production and long term equipment integrity.
Below is a detailed look at four commonly used CIP chemicals and how they contribute to a reliable, repeatable cleaning process.
What is Clean-in-Place and why the right chemicals matter
Clean-in-Place refers to the automated or semi-automated process of cleaning interior surfaces of process equipment without dismantling any pipework, tanks or fittings. A CIP system circulates cleaning, rinsing and sanitising solutions through the same path used by the product, ensuring that all internal surfaces are exposed to carefully controlled flow, temperature and concentration levels.
Choosing the correct chemicals matters because each chemical type targets specific soils and residues. Fats, proteins, sugars, minerals and microbial contaminants require different cleaning actions. The wrong selection can increase cleaning time, reduce product safety or contribute to corrosion and equipment wear.
Chemical efficiency also impacts energy usage, water consumption and overall operating costs. A balanced chemical regimen helps to achieve high levels of hygiene while supporting environmental and sustainability goals. In most CIP systems, four broad categories of chemicals are commonly used.
Types of CIP Chemicals Used in Cleaning
Caustic Chemicals
Caustic chemicals are typically based on sodium hydroxide, also known as caustic soda or NaOH. They are the primary detergents used in many Clean-in-Place wash cycles due to their high pH and strong ability to break down organic material. Caustic solutions are usually applied at concentrations between 0.5 and 2.0 per cent, although more heavily soiled surfaces may require levels closer to 4 per cent.
Sodium hydroxide works by softening fats and dissolving protein-based soils, which helps the cleaning solution lift residues from stainless steel surfaces. Caustic detergents generally produce little or no foam, which is beneficial for maintaining efficient pump performance and preventing cavitation within the CIP system.
Because caustic is highly reactive, it is important to monitor concentration and temperature throughout each wash. Elevated temperatures can increase soil removal efficiency but will also increase energy consumption, so settings must be balanced carefully. Regular testing ensures that the solution retains its cleaning strength and is replenished when needed.
Acids
Acid-based CIP chemicals are typically used after a caustic wash to remove mineral deposits, restore pH balance and brighten stainless steel surfaces. The most common choice is nitric acid, often used at around 0.5 per cent concentration. Nitric acid is effective for removing scale, calcium deposits and milk stone, particularly in dairy and high-acid food processing environments. It also assists in dissolving calcified mineral films that accumulate on vessel walls and within pipework.
Phosphoric acid is sometimes used for similar purposes, although it is generally less common than nitric acid. Acids must always be used with caution as they can damage elastomers, gaskets, valve seats and other system components if the materials are not compatible. For this reason, operators should always verify material compatibility before introducing acid into any CIP cycle.
It is also important to maintain the correct wash sequence. Applying an acid wash before a caustic wash in systems where milk deposits are present can cause proteins to coagulate, making the residue more difficult to remove.
Sanitiser and Disinfectants
Sanitisers reduce microorganisms to a level considered safe for food handling and public health. Hypochlorite solutions are widely used and are available in potassium, sodium or calcium forms. Their active ingredient is chlorine, which provides effective sanitising capability at relatively low cost. Hypochlorite solutions work well in systems handling dairy products and other materials prone to bacterial growth.
However, chlorine-based sanitisers must be handled cautiously. They can cause corrosion, staining and pitting on stainless steel if not thoroughly rinsed away. When discharged into wastewater systems, they may also harm beneficial microorganisms used in biological treatment processes.
Chlorine dioxide is an alternative sanitising agent often used in applications with heavier organic loads. It offers stronger oxidising power than bleach and produces fewer corrosive effects, making it a more equipment-friendly option.
Peracetic acid, or PAA, has become increasingly popular as a sanitising agent. It is effective at low temperatures, rinses away cleanly and leaves minimal residue that could damage stainless steel. PAA acts against a wide spectrum of microorganisms including pathogens and bacterial spores and is considered more environmentally favourable. PAA does have a strong odour and must be used in well-ventilated areas but remains one of the most versatile CIP sanitisers available.
Operators must always ensure that sanitising agents are rinsed away thoroughly to prevent chemical reactions. Mixing residual chlorine with acid, for example, can create dangerous gases within the system.
Sterilisers
Sterilisation refers to the complete elimination of all living microorganisms, not just the reduction of their numbers. While chemical sterilants exist, steam remains the most common method in industrial settings. High-pressure steam at approximately 250 degrees Fahrenheit for around 30 minutes provides reliable sterilisation for systems that require aseptic or extended shelf life processing.
Food, beverage and dairy plants generally do not require sterilisation as part of their CIP cycle, but pharmaceutical, biotechnology and ESL product facilities often depend on it as a standard sanitising stage.
Selecting the Right Chemical Regimen for Your CIP System
Selecting the correct combination of CIP chemicals begins with identifying the types of soil present on equipment surfaces. Fats, proteins, sugars, minerals and microbial contaminants all respond differently to various detergents and sanitisers. A successful cleaning programme must also consider the materials used within the system. Some elastomers or non-metallic components may be unsuitable for certain acid or high pH chemicals.
Temperature, concentration and contact time are equally important. Higher temperatures increase molecular movement, improving soil removal efficiency, while higher concentrations often shorten cleaning time. Longer exposure periods can break down stubborn soils but must be balanced against production schedules.
Automation plays a key role in modern CIP systems. Automated dosing, concentration monitoring and cycle control help ensure consistent chemical usage, reduce human error and improve operational safety. Effective automation also minimises water and energy consumption, lowering total operating costs while maintaining a reliable hygienic standard.
Summary and Best Practices
Achieving reliable Clean-in-Place performance depends on using the correct chemical in the appropriate sequence and concentration. Caustic detergents remove organic soils, acids manage mineral deposits, sanitisers control microbial contamination and steam provides sterilisation for specialised applications. Over-compensating with excessive chemical dosing can lead to unnecessary costs and potential corrosion issues, especially in manual or semi-automated systems.
Best practice involves monitoring wash solutions, following the correct wash order, validating temperatures and exposure times and ensuring that all sanitising agents are rinsed thoroughly before returning the system to service. Consistency, repeatability and control are essential for protecting product integrity and equipment longevity.
At ALLMECH ENGINEERING LTD, we support hygienic processing facilities with equipment and guidance designed to make CIP systems dependable, efficient and safe.
Frequently Asked Questions
What determines which CIP chemicals I should use
The choice depends on the type of residue present, the processing environment and the materials within your equipment. Fats require caustic solutions, minerals require acids and microbial risks require sanitisers.
Can sanitisers be reused
Generally no. Sanitisers reduce microbial growth but do not eliminate all pathogens. Reusing them risks spreading contamination.
Is peracetic acid safe for stainless steel
Yes, PAA is widely used because it rinses cleanly and leaves minimal residue that could corrode stainless steel surfaces.
Do I always need steam sterilisation
Only certain industries, such as pharmaceutical and ESL production, require complete sterilisation. Most food and beverage plants use sanitisers instead.
How often should CIP solution strength be checked
Daily checks are recommended, especially for caustic and acid solutions, as concentrations can weaken over time.
