Technical guide for preventive and corrective maintenance of heat exchangers

Heat exchangers play a fundamental role in various industrial systems by facilitating heat transfer between two fluids, or between a fluid and a gas or vapour, such as water vapour. They are widely used in power plants, chemical plants, refineries, HVAC systems and many other applications. As they are essential components for the efficient operation of industrial systems, effective preventive maintenance of heat exchangers is essential to ensure they work optimally.

The primary purpose of a heat exchanger is to efficiently transfer heat from one fluid to another. The two fluids involved in the heat transfer process are often separated by a solid barrier or a series of tubes. This barrier prevents the fluids from mixing while allowing heat to pass through.

Heat exchangers are designed to optimise heat transfer by maximising the surface area available for contact between the two fluids. This is achieved through various configurations, such as shell-and-tube, plate-and-frame, or finned-tube designs (where fins are placed on the tubes to increase the surface area and improve heat transfer). The choice of design depends on factors such as temperature and pressure requirements, fluid properties, and overall system constraints.

Preventive maintenance of heat exchangers is essential for safe and efficient operation. Over time, deposits, dirt, and scale can accumulate on heat transfer surfaces, reducing efficiency and increasing pressure drop. Regular cleaning is necessary to remove these deposits and maintain optimal performance.

There are several effective industrial cleaning methods, including mechanical cleaning, chemical cleaning, and high-pressure water jetting. The selection of the cleaning method depends on the type of dirt, the compatibility of the materials, and the specific requirements of the heat exchanger.

In addition to cleaning, routine inspection and maintenance are important. This includes checking for leaks, corrosion, and other deterioration, as well as ensuring proper fluid flow and overall structural integrity.

Proper preventive maintenance of heat exchangers is essential not only for efficient heat transfer, but also for safety. Failures in heat exchangers can lead to severe consequences, such as fires, explosions, or equipment damage. Therefore, carrying out recommended maintenance practices and scheduling regular inspections is essential to ensure safe and reliable operation.

The importance of cleaning and preventive maintenance of heat exchangers

Heat exchangers are essential components in a wide range of industrial systems, playing a vital role in heat management. They enable heat transfer from one fluid to another, using separate fluid circuits and a barrier to prevent mixing. By facilitating heat transfer, heat exchangers help maintain desired temperature and pressure levels within these systems.

Efficient heat transfer is achieved by maximising thermal conductivity between the two fluids, while minimising pressure drop and ensuring high overall efficiency. Proper preventive maintenance of heat exchangers is of utmost importance due to the potential risks that failure can cause, such as fire and explosion hazards. Therefore, cleaning and proper maintenance are important to ensure optimal and safe operation.

To ensure the efficient and safe operation of industrial and commercial systems, it is important to prioritise the cleaning and maintenance of heat exchangers. Let us look at the main reasons why these services are of utmost importance:

1. Improved efficiency: Dirty or poorly maintained heat exchangers experience a reduction in heat transfer efficiency, resulting in higher energy consumption and increased costs. Regular cleaning and maintenance can restore and improve efficiency, leading to lower energy use and cost savings.

2. Extended service life: The accumulation of dirt, debris, corrosion, and other damaging factors can shorten the service life of a heat exchanger. By implementing proper preventive maintenance of heat exchangers, potential damage can be prevented or minimised, thereby extending the service life of the equipment and reducing the need for costly replacements.

3. Improved safety: Malfunctioning or clogged heat exchangers can create safety hazards, such as overheating or leaks of hazardous substances. Through regular cleaning and maintenance, these problems can be mitigated, ensuring safe operation and minimising risks to personnel and the surrounding environment.

4. Regulatory compliance: Many industries have specific regulations and standards that require regular cleaning and maintenance of heat exchangers. Complying with these regulations is essential not only for safety, but also to avoid penalties and other legal consequences.

5. Optimal performance: Clean, well-maintained heat exchangers operate at peak efficiency, resulting in improved system performance and reliable operation. By scheduling regular cleaning and preventive maintenance of heat exchangers, you can minimise downtime and reduce the need for costly emergency repairs.

By becoming aware of the importance of cleaning and preventive maintenance of heat exchangers, industrial and commercial systems can achieve improved efficiency, extended equipment life, increased safety, regulatory compliance, and optimal performance.

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Types of preventive maintenance for heat exchangers

There are different methods available for cleaning and preventive maintenance of heat exchangers, depending on factors such as tube configuration, level and type of dirt, and cost considerations. Heat exchanger cleaning is typically performed offline (when not in operation), and the three main types of cleaning methods are mechanical, chemical, and high-pressure water cleaning.

Chemical cleaning

Chemical solutions are commonly used for cleaning heat exchangers and have proven effective in removing a wide range of deposit types. However, chemical cleaning has certain drawbacks, such as the need for proper disposal of chemicals, potential environmental risks, and the requirement for additional mechanical cleaning to ensure optimal results.

Mechanical cleaning

Mechanical cleaning involves the use of tools selected based on the type of deposit to be removed. Moulded plastic cleaners are effective for light sediment, while brushes can be used for microbial deposits and sediment. Brushes can be adapted to clean pipes with various surface enhancements, such as fins, spirals, metal inserts, or epoxy coatings. Metal cleaners are designed for harder deposits and come in different designs to match the deposit and tube diameter. If you are unsure which industrial cleaning or preventive maintenance service your heat exchanger equipment needs, you can rely on experienced companies such as Western Alpha to advise you.

High-pressure water cleaning

High-pressure water cleaning has become increasingly popular for cleaning heat exchangers due to its effectiveness. It can efficiently remove mineral deposits, scale, biological matter, and other debris. High-pressure water systems also facilitate easy collection of the removed deposits, allowing for better monitoring of accumulation levels over time and establishing a more regulated inspection and cleaning cycle.

Other cleaning systems and processes, such as combined air and water systems or compressed air systems, may also be available, each with its own specific practices and effectiveness depending on the characteristics of the tube and tank. Regardless of the method used, it is essential to rely on a highly trained heat exchanger cleaning team.

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Steps for preventive maintenance of heat exchangers

The cleaning and preventive maintenance of heat exchangers is a complex, multi-stage process involving many steps. In addition, proper cleaning must be performed by a certified technician to ensure that all steps are completed thoroughly and that all regulations are followed. Some of the tasks performed by a heat exchanger technician include:

1. Multiple inspections: From initial inspections documenting the condition of the heat exchanger when the technician arrives, to post-flushing and post-job inspections, the heat exchanger technician will carefully inspect and document the condition of the heat exchanger throughout the maintenance process. This helps managers and maintenance staff understand the condition of their equipment, better predict when preventive heat exchanger maintenance will be necessary, and develop an overall picture of the status of their heat exchange systems.

2. Complete cleaning and coating of tubes: The tubes in the exchanger are essential for all heat exchangers, and they must remain clean and properly coated to ensure that heat exchange is carried out efficiently. Therefore, technicians will thoroughly clean and coat all exchanger tubes, using only industry-certified techniques and materials.

3. Renovation, cleaning, inspection, replacement, and plugging of pipe covers: Pipe covers must be clean to ensure that there are no breaks in the containment seals. Therefore, heat exchanger preventive maintenance professionals will conduct a thorough review of all aspects of the covers, cleaning them and repairing or replacing them as necessary.

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When should heat exchangers be cleaned and undergo preventive maintenance?

Heat exchangers should be inspected at least once a year, with more frequent inspections recommended for those operating in dirty or corrosive environments. The frequency of cleaning and maintenance of heat exchangers depends on several factors, including:

1. Heat exchanger type: Different types of heat exchangers have different cleaning and maintenance requirements. For example, shell-and-tube heat exchangers may require more frequent cleaning than plate heat exchangers.

2. Operating conditions: The operating conditions of the heat exchanger, such as temperature, pressure, and fluid flow rate, can influence the rate of dirt and debris accumulation and the need for cleaning.

3. Environmental conditions: The environment in which the heat exchanger operates, such as the presence of corrosive or abrasive substances, may affect the need for cleaning and maintenance.

4. Industry regulations: Some industries have regulations and standards that dictate the frequency of cleaning and preventive maintenance for heat exchangers.

Safety when performing preventive maintenance on heat exchangers heat exchangers

The safety of heat exchangers is important to ensure that their operation does not cause harm to people or other systems. Here are some safety tips to consider to ensure that your heat exchanger operates as expected:

Irrelevant temperature: Extreme temperature conditions can affect heat exchangers both inside and outside the system. While some fluids, such as refrigerants, remain very cold, process fluids are often heated to high temperatures. Depending on the environment and location of the installation, certain heat exchangers that are outdoors are subject to extreme temperatures.

Phase change: To avoid harmful phase change, it is important to keep the temperature within acceptable ranges. Many heat exchangers are not designed with phase change in mind, but some are compatible with it. For example, pressure will rise rapidly if the temperature rises to the point where the cooling water boils and turns into steam. If the system is not designed to withstand these high pressures, the effects can be dangerous.

Pressure change: Pressure change can detect high pressure variations, but flow meters on the inlet and outlet sides of the heat exchanger can also detect pressure. It is important to check the pressure drop across the heat exchanger under normal conditions, because if it increases, the flow may be restricted, and it will not be safe for workers.

Corrosion and fouling: When planning preventive maintenance for heat exchangers, it is important to bear in mind that surfaces can corrode when process fluids come into contact with them, leading to the accumulation of rust or scale that can reduce the diameter of the tubes and impede flow. In addition, low-velocity regions of the heat exchanger may experience a build-up of dirt and contaminants in the process fluid. For example, a small amount of sand and leaves, or even a small amount of resin that is more solid and less viscous, can accumulate in water pumped from a nearby lake.

How to choose a preventive maintenance company for heat exchangers

When selecting a service company to perform preventive maintenance on heat exchangers, you will want to rely on highly experienced personnel who are knowledgeable in the use of the best tools and techniques. Upgrades and modern technology should be utilised to help you save money by requiring less downtime.

A thorough understanding of corrosion, fouling agents, and coatings is highly recommended. This ensures that the best methods and safety measures are employed in conjunction with an understanding of the heat exchanger design. The end result will be maximised equipment life cycles and fluid flow, along with minimised costs and operational risks.

Choosing a heat exchanger preventive maintenance company can help you determine whether your system requires maintenance.

Conclusion on preventive maintenance of heat exchangers

In conclusion, preventive maintenance of heat exchangers is very important to ensure their optimal performance and extend their service life. Throughout this guide, we have highlighted the importance of conducting regular inspections, implementing effective cleaning practices, and addressing any operational issues in a timely manner.

Preventive maintenance not only helps improve energy efficiency and reduce operating costs, but also minimises the risk of unexpected failures that can result in system interruptions and costly damage. On the other hand, corrective maintenance allows specific problems to be addressed and normal equipment operation to be restored, ensuring continuity of operations.

By adopting a comprehensive and systematic approach to preventive maintenance of heat exchangers, companies can optimise the performance of their systems, comply with industry regulations, and ensure the safety of personnel and the environment. It is essential to have trained and experienced personnel to carry out these tasks, as well as to use the most advanced tools and technologies to obtain the best results.

Remember that implementing a well-structured and regular maintenance programme is a strategic investment that contributes significantly to the operational efficiency and long-term sustainability of any industrial facility. By following the recommendations in this guide, operators can ensure that their heat exchangers operate efficiently, safely and reliably at all times.