Understanding the Heat Exchanger Tubes

A heat exchanger is a mechanism that transfers heat to a solid object and a fluid or among two or more fluids. These fluids are separated by a wall so that they do not get mixed, on the other hand, they might also be in direct contact. Heat exchangers play a vital role in the working of many systems and processes. For instance, the heat exchanger is used in the boiler of the hot water, the freezer. In the former cases heat is transferred to the boiler and in the latter, the heat is transferred away so the freezer remains cool.

In industries, they are used in different processes. For example, in the power industry, water has to be heated into steam to run the turbines. The steam is superheated so as to avoid any moisture as it may damage the turbines and can cost millions to the company. So it is essential to keep the heat exchangers in top condition.

There are many types of heat exchangers. The double pipe heat exchangers are very simple in mechanism and are used in industries. They are cheaper in maintenance and design. On the contrary, they have low efficiency and occupy a huge space. Because of this reason modern industries use more efficient heat exchangers called the shell and tube or plate.

The heat exchanger has several tubes. These are available in a wide variety of materials including duplex stainless steels, austenitic stainless steels, nickel alloys, zirconium and titanium that are suitable for all types of heat exchangers like condensers, seawater coolers, heaters, evaporators, and re-heaters.

The heat exchanger tubes are finned, plain, internal or external. Normal heat exchanger units make use of plain tubes while the finned tubes provide a high heat transfer surface. Another kind of tube is the duplex tube which is fitted within a tube by drawing the tube which is out into the inner tube.

The diameter of the tubes varies from 6mm up to 40mm. The thickness depends on the construction materials and its diameters. The tube length varies from 0.5 to 6m. They lay either on a square or an equilateral triangular pitch.

 If the heat exchanger tube breaks, it can be fixed by expanding the ends of the tube in the tube sheet holes by expanding and rotating tool.

Applications and Uses

 
The heat exchanger tubes are used for the different purposes such as heating or re-heating, cooling of gases, fluids or air in many industries like the chemical, hydrocarbon processing, oil refining, and aerospace.

It is also used in Power generation i.e. Nuclear, Solar and Thermal Power Plants, Oil and Gas, Refinery and Petrochemical, Process Industries, Chemical and Fertilizer, Atomic energy, Defense and Aerospace, Pulp and Paper Industries etc.

The Heat Exchanger Tubes are Available in Two Types – a) Straight b) U- Bent

 

a)    Straight tubes:

 
The two ends of the tube are fixed to the tube sheets. One fluid goes to the tube and the other to the shell. They have excellent high fouling qualities. They are used where there is frequent high-temperature cross. The straight tubes heat exchanger can be cleaned easily.

b)    U- bend tubes:

 
U – bend tubes consists of a U – shaped tube fixed to a tube sheet and is supported by tube baffles. These are of superior quality. U – bend tubes can be customised as per the client’s needs. These tubes are cut with specific leg lengths, its ends are deburred and the bores are cleaned properly with a dry air.

While Manufacturing Heat Exchanger Tubes There Are Several Factors to be Considered:

 

Dimensional Tolerances for Diameter

 
The dimensional tolerances for diameter are crucial in ensuring that the tubes fit perfectly into the heat exchanger. The diameter of the tube should be within a specified range, which varies depending on the application. Manufacturers use specialized machines and equipment to ensure that the diameter is accurate and consistent throughout the length of the tube. The design or engineering drawings usually specify the tolerance range, and the manufacturing process must adhere to these requirements.

Eccentricity

 
Eccentricity refers to the distance between the center of the heat exchanger tube and its outer surface. This distance should be uniform throughout the length of the tube, and any deviation can affect the efficiency of the heat exchanger. The manufacturing process should ensure that the eccentricity is within the specified tolerance range and the tube is symmetrical.

Wall Thickness

 
The wall thickness of the heat exchanger tube is another crucial factor that affects its performance. The thickness of the wall should be uniform, and any deviation can lead to uneven heat transfer, affecting the efficiency of the system. The wall thickness is usually specified in the design or engineering drawings, and the manufacturing process should ensure that the tube complies with these requirements.

Length

 
The length of the heat exchanger tube is also essential, and any deviation from the specified length can affect its efficiency. The manufacturing process should ensure that the length of the tube is accurate and consistent.

Mechanical Properties

 
The mechanical properties of the heat exchanger tube are crucial in ensuring its durability and longevity. The tube should be able to withstand the pressure and temperature variations during the operation of the system without deformation or damage. The mechanical properties that must be considered include tensile strength, yield strength, elongation, and hardness. The manufacturing process should ensure that the tube meets the required mechanical properties, and specialized testing and inspection methods are employed to verify the properties

Corrosion Resistance

 
Heat exchanger tubes are subjected to various corrosive environments during their operation, and the tube’s resistance to corrosion is essential to ensure its longevity. The manufacturing process should ensure that the tube is made of materials resistant to corrosion and can withstand the corrosive environment. The choice of materials depends on the specific application and the corrosive environment to which the tube will be exposed.

Surface Finish

 
The surface finish of the heat exchanger tube is also an essential factor that affects its performance. A smooth surface finish is crucial to ensure efficient heat transfer, and any irregularities or roughness on the surface can lead to decreased efficiency. The manufacturing process should ensure the surface finish is smooth and defects-free; specialized equipment and techniques are used to achieve this.

In addition to the above factors, several other considerations must be taken into account during the manufacturing process of heat exchanger tubes. These include the selection of the appropriate welding method, the control of residual stresses, the prevention of contamination, and the application of coatings to enhance corrosion resistance and improve heat transfer.

The manufacturing process of heat exchanger tubes is a complex and specialized process that requires expertise and experience. Manufacturers must adhere to strict quality control procedures and use specialized equipment and techniques to ensure the tubes meet the necessary specifications and requirements. The tubes must undergo rigorous testing and inspection to verify their mechanical properties, corrosion resistance, and surface finish, among other factors.

Frequently Asked Questions About Heat Exchanger Tubes

 

What materials are used to make heat exchanger tubes?

 
Heat exchanger tubes can be made from a wide range of materials, depending on the specific application and the corrosive environment to which the tube will be exposed. Common materials used to make heat exchanger tubes include stainless steel, copper alloys, nickel alloys, titanium, and carbon steel.

How are heat exchanger tubes cleaned and maintained?

 
Regular cleaning and maintenance are necessary to maintain the efficiency and longevity of heat exchanger tubes. The cleaning method will depend on the type of heat exchanger and the specific application. Common cleaning methods include chemical cleaning, mechanical cleaning, and high-pressure water cleaning. Regular maintenance should also be performed to check for any signs of corrosion, wear, or damage.

How do I select the right heat exchanger tube for my application?

 
Selecting the right heat exchanger tube for your application requires a thorough understanding of the specific requirements and conditions of the system. Factors to consider include the operating temperature and pressure, the corrosive environment, the flow rate, and the material compatibility. It is recommended to consult with a qualified engineer or heat exchanger specialist to determine the best tube material, size, and design for your application.

How are heat exchanger tubes tested and inspected?

 
Heat exchanger tubes undergo rigorous testing and inspection to meet the necessary specifications and requirements. Testing methods include hydrostatic, eddy current, ultrasonic, and X-ray testing. Inspection methods include visual inspection, surface inspection, and dimensional inspection. These tests and inspections help verify the mechanical properties, corrosion resistance, surface finish, and other critical factors of the heat exchanger tube.

Anand Seamless Manufactures High-Quality Heat Exchanger Tubes

 
At Anand Seamless Ltd, we are committed to manufacturing high-quality heat exchanger tubes that meet the specific needs of our customers. Our team of experts has extensive experience in designing, manufacturing, and testing heat exchanger tubes, and we are always available to answer any questions you may have.

If you are looking to improve the performance and reliability of your heat exchanger system, then it is essential to have a good understanding of the various types of tubes available, their materials, and how they work.

Visit our website to learn more about our heat exchanger tubes, carbon steel and alloy steel seamless tubes and pipes, finned tubes and pipes, and how they can benefit your business. We also offer a range of customized solutions to meet your specific requirements. Contact us today to discuss your needs, and let us help you find the perfect heat exchanger tube solution for your application.