The engines of ships need to be cooled, just like with any other type of engine, although they usually use the water that they are navigating through in order to keep the engine cool. This means that ships and boats need to be properly equipped to prevent water leaking into the interior of the ship. If any cracks or leaks arise, it is possible for water to seep into the air system or the water system. The result can be that the boat or ship fills with water creating a sink hazard. Additionally, salts and minerals, and other debris can clog the cooling system. This includes aquatic plant and animal life, garbage, and mollusks. It can be extremely difficult to clean the heat exchanger tubes on a large ship. It’s not a task for a novice. It takes high level expertise and the correct heat exchanger cleaning equipment. Therefore, it is best to stay on a rigid maintenance schedule of heat exchanger cleaning.

In order to clean air to water heat exchangers, a high level of expertise is required because it is a labor intensive job that requires the technician to get access to the heat exchanger tubes and use a variety of heat exchanger cleaning equipment, which will include metal and plastic scrapers, chemical solutions, brushes, water jets. Before the job even begins, the heat exchanger tubes must be inspected to determine what equipment and manpower will be needed.

There are all sizes of heat exchangers because they are used in all sizes of boats and ships, from small recreational craft, to large tankers and aircraft carriers. Logically, the size of the heat exchanger tubes are relative to the size and needs of the boat. Some tubes are even less than one inch in diameter, while others are large enough for a adult male to fit clear inside. They can be hundreds of feet long too. The heat exchanger tubes that is, not the adult males. The tubes can also be constructed from a variety of different metals, which will be part of assessing the best cleaning method. It will also be considered as to whether there is a need to recoat the tubes. These are all variables that need to be taken into consideration before planning the best heat exchanger cleaning equipment for the job.

Old School Tube Cleaning Vs. New Techniques

With the older heat exchanger tube cleaning technologies, tube cleaning was not always very good, and refouling of the tubes would often happen very soon after cleaning because of the inefficiency of the cleaning. This is because the main method was water jetting. This method pushes water through the tubes in a single direction, and as a result, it was possible for the build up that was being cleared out. This method also created an increased need to recoat the surface, because it left some of the contamination on the sides of the tubes, leaving the tubes prone to corrosion. Some of the recoating was just putting a new surface right over top of the contaminants. This is like painting over a rust spot on your car. If you don’t remove all the rust, the new paint won’t take very well. The result was a high likelihood of refouling of the tubes.

New methods use a much higher pressure and employ the use of a rotating head, which clears the inner walls more completely because the head is in constant rotation. Therefore, the recoating takes better because it is on a much more effectively cleaned surface. In many cases the tube is nearly like new after the recoating has been completed.

There is also an environmental benefit to this method, as it only uses water to clean the heat exchanger tubes. There are no toxic chemicals used which is both eco-friendly, and more cost effective than using expensive and harmful chemicals. Our oceans and seas are the foundation for life on this planet, so this is a very important consideration. This method can be used for all metals, whether it is a soft brass or hard titanium, and it will not harm the metals used.

After a thorough heat exchanger cleaning, it is important to perform a extensive inspection. This is the time to detect leaks that were not noticed prior to cleaning. It is also an opportunity for the boat owner to see if the cleaning company has done their job well. This inspection is most often done with tiny robotic cameras. Other types of inspection include manual underwater inspections of the outer areas of the heat exchanger. The inspection allows the ship to be cleared as confirmed that the heat exchanger has been properly maintained, and the ship is seaworthy.

Heat exchanger tube cleaning is an essential part of the maintenance and service schedule of a boat or ship that ensures proper functioning of the ships engine. There have been many advances in heat exchanger cleaning equipment that have greatly increased the efficiency of heat exchanger tube cleaning, and simultaneously decreased the cost and reduced it’s environmental impact. Whether it is a small recreational craft, or a large military or industrial ship, it needs this important service on a regular basis in order to stay operational.

Heat exchangers often go so long without being properly cleaned and maintained that by the time there is a heat exchanger cleaning, the original specs and records have been lost or misplaced. This creates an additional problem, because without the original specs, no one knows what kind of performance the heat exchanger is supposed to have.

Once the heat exchanger finally is opened up for cleaning, it’s common to find that it has become so fouled that the heat exchanger cleaning takes significantly longer than it would have if it had been regularly maintained and cleaned. Ultimately, the lack of regular maintenance and cleaning results in a higher cost, longer cleaning duration, and greater loss of production.

This might sound like some sort of a rare, worst case scenario, but it’s entirely routine for the specialis cleaning companies. When cleaning is done, it’s often done without any real knowledge of what kind of performance benefit there will be, and how long this increased efficiency will last.

One of the most used heat exchanger configurations in industrial use is the straight of hairpin shell-and-tube-exchanger. This has bundles of hundreds or thousands of small-bore tubes. Even a moderate amount of scaling can take considerable cleaning and effort to return the heat exchanger back to optimal performance. If the outside of the bundle has heavy scaling, it’s exponentially more difficult to adequately clean the heat exchanger.

Advancements in design would be able to make heat exchanger cleaning faster, safer, and result in better waste containment. This would result in less time spent offline, and better performance.

Currently, heat exchangers are generally designed to have the capacity to operate even when they are significanly fouled. They are designed to operate with about 30% or 40% excess capacity. This is what industrial facilities want. They prioritize continued functionality over ease of maintenance and cleaning. Heat exchangers are designed and installed to use one of 3 methods of cleaning: mechanical, chemical, or pressure-jetting. This has been the standard for over 50 years.

Refineries, like other industries, use a 21 say shutdown process during which maintenance, including heat exchanger cleaning is done. This is the way it has been done for decades. Industry continues to use the same methods for heat exchanger cleaning that it has always used. The primary method is pressure washing with water.

It’s normal for a company to have their heat exchangers designed to continue running, even if not at optimal performance, instead of having them designed for efficiency, or ease of cleaning. This could require more frequent cleaning, but it would be easier, safer, and more cost effective, resulting in a more efficiently performing heat exchanger. BP (British Petroleum) was able to cut cleaning time of a shell and tube heat exchanger down to 3 hours by changing their heat exchanger cleaning method. Prior to that, cleaning would take 3 days.

If a company designs their heat exchangers for ease of cleaning and maintenance, the plant can remain at near full production capacity throughout the duration of the cleaning process. Banks of heat exchangers can be taken offline, while the rest remain on line. Heat exchangers designed to allow the header to be removed allows for heat exchanger cleaning with alternate methods to the usual high pressure water jet. This can cut heat exchanger cleaning time down to just a few hours, instead of a few days.

More frequent cleaning can also reduce the occurrence of heat exchanger fouling, and also minimizes the amount of time that the tubes are exposed to open air during cleaning. This results in a reduction of corrosion of the heat exchanger tubes.

Cleaner, smoother heat exchanger surfaces allow for more efficient heat transfer. When fouling does occur, it is easier and less time consuming to do the heat exchanger cleaning, and also allows for a wider variety of cleaning methods.

Generally, plants have heat exchanger cleaning intervals of 3 or 4 years. Unfortunately, spreading out the time period between cleanings winds up with a greater cost, not a lesser one. In the short term, it seems like a good idea to stay fully operational, but when the time for maintenance finally does come, down time, lost productivity, and cost is significantly higher than the shorter down times of a quicker maintenance schedule would be. Long maintenance schedules result in a much bigger job.

Big picture thinking, and better design can ultimately be a huge advantage in minimizing the cost of heat exchanger cleaning.