In this guide, you will find all information you’re looking for about tube bundles.
Whether you want to know the cost, designs, applications or quality tests, all that information is available right here.
Keep reading to learn more.
- What is a Tube Bundle?
- How does Tube Heat Exchanger Work?
- Are Tube Bundles Customizable?
- What is the Cost of Tube Bundles?
- What are the available Tube Bundle Configurations?
- How do you Clean Tube Bundles?
- What are Tube Bundles used for?
- What is the Material used to make a Tube Bundle?
- What are the Different Types of Tube Bundles?
- Are there Size Limitations to Tube Bundles?
- What are the Disadvantages of Tube Bundles?
- What are the Applications of Tube Bundles?
- Are Tube Bundles Replaceable?
- What are the Components of a Tube Bundle?
- How many Passes does a Tube Bundle have?
- What Quality Certifications should Tube Bundles have?
- What are the Quality Tests and Inspection Requirements for Tube Bundles?
- What are the Capabilities of Tube Bundles?
- When should you Replace a Tube Bundle?
- What Heat Exchange Forms do Tube Bundle offer?
- What are the Advantages of Stainless-steel Tube Bundles?
What is a Tube Bundle?
A tube bundle is a well packed collection of pipes you can use as a radiation core in heat exchanger device.
They give a compact way to cool or exchange heat via a nest of tubes.
Tube bundles are often housed in outer casing or a tubular shell with a constant flow of fluids moving through it.
There are tube bundles that allow liquid to liquid heat exchange as well as steam to liquid heat exchange.
How does Tube Heat Exchanger Work?
With an increase in recipient surface area and combined radiation, the heat transfer process becomes efficient.
This specific principle forms the basis of operation for the tube heat exchanger.
The tube bundle has large number of tubes that offer wide contact surfaces.
This enables efficient and quick heat transfer.
You have to calculate the layout of the pipes of the tube bundle carefully.
The pipes move through many bulkheads or baffles which maintain the spacing relationship all through tube bundle length.
Besides, the fluid exit and entry configurations of the bundle are determined by which of the two tube bundles are used.
The heating source/fluid goes via the tube and heat is exchanged as the two areas make contact.
Are Tube Bundles Customizable?
Of course, yes.
Tube bundles are customizable.
You can customize aspects such as physical dimensions, materials and configuration depending on the intended application.
You can also customize replacement tube bundles for your existing heat exchanger device.
The customized tube bundle pieces meet all of the industry standards/specifications such as TEMA, ASME requirements as well as complying with sections I, IV, VIII & Div. 1.
What is the Cost of Tube Bundles?
Tube bundles are cost-efficient.
The price of a replacement tube bundle for 4 pass heat exchangers is $1,041.18.
Similarly, a single piece of tube bundle can cost US$80.00 – US$100.00.
The price of a tube bundle depends on dimensions such as the weight, size, design, type, thickness or diameter of this component.
The cost of a tube bundle includes the design, raw materials, fabrication, manufacture, installation, maintenance and price of the tube bundle.
Since they are made using high quality steel materials and other alternatives, they have a longer service life and quality.
You may only perform limited maintenance on the tube bundles.
What are the available Tube Bundle Configurations?
There are two types of tube bundle configuration.
This is the arrangement/layout of the component in a heat exchange device.
i. U-tube Layout
U Tube bundle layout
This configuration features both entry and exit points on the same side of the shell on the cap of a tube shell separated into two sealed chambers.
The tubes in the bundle leave the entry chamber and move to the other end of the shell where they make a U-bend and get in the opposite direction to the exit chamber.
Some of the advantages of this configuration are:
- They accommodate high-temperature differentials well
- Ease most contraction stresses and thermal expansion in the bundle
- It is easy to dissemble for maintenance with the bundle being slid out as a modular unit
ii. Straight Tube Arrangement
Straight tube bundle
This configuration consists of straight tubes often open on either end of bundle into exit or entry chambers which make the shell’s end caps.
A hot fluid is pumped through the bundle in a straight line from one end of the outer casing to the other.
To determine the number of tubes in this tube bundle, simply count the tubes manually.
This configuration is often popular because it involves lower installation costs.
How do you Clean Tube Bundles?
Tube bundles are easy to clean.
To clean tube bundles, you must remove them from inside the heat exchanger system.
You then clean the inside and exterior surface using suitable fluids before returning them back the device.
Cleaning of the tube bundles is possible if done chemically.
You can flash the chemical cleaning agent at high pressures directly into the inner walls of the tube bundles.
It removes any residues which could have stuck to the component.
Following this, you rinse the tubes very well so that it is clean before operation reconvenes.
In the event that there are leftover residues, the damage can be destructive to the material of construction as well as potentially contaminate the fluid/product.
Similarly, you can clean the insides of the tube bundles mechanically.
Since the outside of the tube bundles is welded, it makes it difficult to clean the part mechanically.
You, therefore, clean the outside of the tubes chemically.
You can reach the tubes without difficulty making it easy to clean the insides of the tubes without necessarily removing the pipes.
U-tubes are a bit difficult to clean because of the U curve.
This curve makes it difficult clean the bend mechanically; it becomes cumbersome for the cleaner to have to reach these bends contrary to cleaning a straight tube.
Chemical cleaning of U-tubes is not advised because it is not possible for some types of fouling.
Scaling is a type of fouling that hardens to the sides of tubes making it hard to clean unless there is use of physical force.
When scales form at the point of bend in the U- tube bundles, physical force has to be applied to eliminate the fouling.
The only solution in this case is using clean fluids on u-curves.
What are Tube Bundles used for?
Tube bundles aid in heat transfer within the device offering larger heat transfer surface area.
They are used for the following purposes:
- HVAC applications
- Compressor cooling
- Industrial applications
- Power generation
- Spas, water baths, and swimming pools
What is the Material used to make a Tube Bundle?
Tube bundles are often manufactured to meet a customer’s requirements.
They can be made with a variety of materials depending on the temperatures the tube bundle will manage to handle as well as the needs of application.
However, some of the materials used to make this device include:
- Stainless Steel 316
- Carbon steel tubes
- Admiralty brass
- Carpenter 20
What are the Different Types of Tube Bundles?
There are two main types of tube bundles:
· Replacement Tube Bundles
You can use replacement tube bundles in the boiler water, steam, and high-temperature hot water bundles.
They act primarily as replacements if the tube bundle in the device completely fails.
· Fixed Tube Bundles
The tubes in this device cannot be removed. They are securely attached to shell of the heat exchanger.
· U-tube Bundles
This type of tube bundle is also fixed to the device such that you cannot easily remove it when cleaning or doing repairs.
To count the number of tubes in this bundle, simply count the number of full Us.
It has a U curve at one corner of the tube.
Note: the pipes in the tube bundles are often made of copper or steel material depending on the intended application.
Are there Size Limitations to Tube Bundles?
No, tube bundles come in different dimensions depending on the intended application.
The diameter and length of the piping affects the functioning/operation of the heater they are installed in.
As such, the tube bundles come in different sizes ranging from small to large sizes for wide applications.
What are the Disadvantages of Tube Bundles?
While tube bundles are often highly effective and useful components in a heat exchanger device, they also have some weaknesses.
Some of these disadvantages include:
- Risk of corrosion as the tubes are made using steel material
- Fouling is highly likely to occur considering that the U-tube has a bend that is hard to reach.
- Tube vibration occurs because of the smooth inner surface of the tubes
- Lower heat transfer efficiency due to smooth walls of the tubes
What are the Applications of Tube Bundles?
Tube bundles are highly flexible and versatile.
They can be applied in devices that are exposed to high temperatures and pressures.
Some of the applications of tube bundles include:
- Food and beverage
- Oil & gas
- Metals & mining
- Pulp & paper
- Petrochemical processing & refining
Are Tube Bundles Replaceable?
Of course, yes.
Manufacturers can build replacement tube bundles that can be used as replacement in existing heat exchangers.
After a while, tube bundles deteriorate due to pressure, corrosion, and high temperatures.
As such, you have to replace the faulty tube bundles with new ones.
If your heat exchanger still has a good service life but a failed tube bundle, you can replace the tube bundle to extend its service life.
You can buy a replacement tube bundle or another type of tube bundle which is compatible with the device you intend to use in your applications.
What are the Components of a Tube Bundle?
There are several parts that go into a tube bundle.
Some of the components that you have to manufacture for the tube bundle are:
Baffles; they direct the flow of fluid across the heat exchanger, as it moves over and around the tube bundle.
It is imperative to know the number of baffles, the spacing between them and the type of baffle to properly regulate the flow.
Baffles have to fit perfectly within the shell to avoid loss of performance from fluid bypass around the baffles.
Instead of the shell, baffles are attached to the tube bundles can be easily removed for maintenance.
Bolt holes are optional in a tube sheet.
The majority of bolts that pass through the shell and head of an exchanger often pass through the tubesheet.
Tubesheet diameter must be larger than the tube bundle diameter.
Due to this, tubesheet can be properly fitted and still hold all the tubes in the bundle.
The thickness of your tubesheet will depend on the volume and use of tube bundle.
The thickness varies between 5/8” to 3”.
The overall length of the tube includes the full length of the tubesheet as well as the last bend of the tubes.
“D” bundle diameter is the hole diameter required for a tube bundle to fit inside a tank or shell.
It includes tube supports and baffles.
You can measure it by taking the circumference of the shell and dividing by 3.14.
Tube supports; aid in anchoring of the tube sheet in the tube bundle.
How many Passes does a Tube Bundle have?
To determine the number of passes through the tube bundle simply look at the tube sheet.
Tube bundles have four main passes.
- 2 pass
The majority of tube bundles have 2 passes.
It shows that there are two routes that the fluids can pass through as they allow fluid flow through the tube bundle.
These below passes often have lower tube counts.
Tube counts are based on the 1 5/8″ triangular pitch for 1 1/2″ O.D. tubes and the 15/16″ triangular pitch for 3/4″ O.D. tubes.
- 4 pass
- 6 pass
- 8 pass
The number of passes selected for a tube bundle depend on customer specifications as well as the availability of tube bundle passes.
What Quality Certifications should Tube Bundles have?
For a tube bundle to be traded in different markets across the world, they must have some of the quality certifications shown below:
- ASME Certifications
These certifications assure the users and customers of high quality and durable tube bundles.
What are the Quality Tests and Inspection Requirements for Tube Bundles?
In testing the tube bundles, you prove that the properties of the tubes are consistent with the relevant standards, requirements of the order and customer specifications.
Some of the tests are according to customer specifications, mandatory or optional.
· Eddy Current Testing
This is the best and most effective way of evaluating the lifespan and condition of the tubes.
It is applied to detect pitting, corrosion, erosion, cracks and other possible changes to the exterior and interior surface of the tubes.
It involves using electromagnetic induction to determine defects in tubing.
You insert a probe into the tube and push through the whole length of the tube.
The electromagnetic coils in the probe generate eddy currents and are then monitored by through measuring probe electrical impedance.
The results you collect from this process detail the tube defects. With this test, you can detect defects instantly making it a convenient test.
This process however requires specialist equipment and expertise as it is highly specialized.
You can perform this test through coatings and pain.
It is suitable for tube bundles made of stainless steel, titanium, or copper.
· Mechanical Properties Test
This test emphasizes the impact bend, hardness and tensile properties of the tube bundles.
Through the test, it shows that the tube bundle has the right properties to withstand the pressures and temperatures of the fluids/application.
· Technological Tests
It focuses on the aspects of flaring, flattening, bending, flanging, or ring test of tube bundles.
· Tube Hydraulic Test
This test helps in detecting any potential leaks in the tube bundle.
It involves exposing the tube bundle to a set amount of pressure, if it does not burst then the device has high integrity.
· Tube Hydrostatic Test
Once the tubes have been manufactured, they are subjected to hydrostatic testing.
The total amount of pressure applied on the tubes is based on the value set in the approved drawing.
No pressure drop or leak can be observed while the device is under pressure.
· Tube Bundle Inspection
It involves inspecting the bundle dimension based on the drawing that was approved at the design stage.
The diameter of the baffle as well as the distance between them is controlled and also meets the acceptance tolerances indicated in the drawing.
You also have to control the tightness of the stay spacers and bolts.
The cleanliness of the shell must also be verified and the insides of the tube are well and fully welded according to the drawings in the design.
· Tube Inspection
Before building a tube bundle, you have to check the ovality, thickness, inside and outside diameter of the tubes.
While doing the inspection, one should refer to the ASME section II to retrieve the acceptable tolerances.
For instance, if the material for your tube is SA 179, you must look to SA 179 which refers to the SA 450 for acceptance tolerance.
This is the specification for the general requirements for Ferritic Alloy, Carbon, and Austenitic Alloy Steel Tubes.
Also, make sure that the values and measurements fall within the acceptance range.
· Tube Rolling Inspection
This aspect of the tube bundle undergoes checking based on customer specification.
After rolling, there is a reduction of the walls, and depth of roll is measured and will meet the specifications of the customers.
Any wall reduction should not be less than 5% and not more than 8% of the wall thickness of the tube.
What are the Capabilities of Tube Bundles?
Some of the capabilities of tube bundles are below but they are not limited to:
- Double wall vented tube bundles
- ASME stamping is available
- Nozzles and tank collars
- Specialty and standard alloys
- Fuel oil heater tube bundles
- Tank heater tube bundles
- Straight or U-tube (enhanced tube, Lo-Fin, Low-Fin, Intergral Tube Bundles)
- Floating or Fixed tubesheet (In Straight or U-Tube)
When should you Replace a Tube Bundle?
You can obviously replace your tube bundles when they are rendered useless/non-functional.
Replacements of tube bundles occur when they have leaks that arise from corrosion.
Often these leaks appear years after the operation.
Fluid corrosion leaks occur on the lower half diameter of the tube.
To spot them, look for pinholes on the device.
However, replacing the U tube or straight tube bundles can be a serious problem.
They are often mounted deep inside shell far from the service personnel.
When repairing a bundle, you have to remove it and this is the time when you measure it for a new tube bundle.
You then place the repaired one back into the device unit.
Following this, you place the repaired one back to the device’s unit.
The very first leaks are often a precursor for more future leaks.
What Heat Exchange Forms do Tube Bundle offer?
Usually, tube bundles have a large combined surface area that enables efficient heat transfer of heat or cooling of fluids within the tubes.
Thus, hot gases or liquids are circulated within the tube bundles.
Tube bundles offer two main heat exchange forms:
· Liquid to Liquid
This heat exchange process involves an entry fluid in liquid form transferring its heat to the exit fluid.
Similarly, it can be entry fluid cooling the exit fluid before it leaves the heat exchanger device.
· Steam to Liquid
Steam to liquid heat exchange form involves an entry fluid (steam) transferring heat to the exit fluid (liquid) or vice-versa.
What are the Advantages of Stainless-steel Tube Bundles?
Are economical; typically, under the same heat exchange area, stainless steel tube cost is around 80% that of copper tube cost.
Hence can be changed to replace the tube bundle.
You have to heat exchange a tube bundle in a protective gas to 1050 ℃ high-temperature heat treatment to relieve the welding stress.
The performance of the heat exchange process is good.
Good anti-fouling performance: It occurs due to the thinning of the thickness of the bottom layer of its boundary layer and smoothness of the inner wall of the tube.
Efficient heat transfer also occurs due to the mechanical properties of the grade of the stainless-steel material chosen.
Since the development of tube bundles involves the use of high-quality stainless-steel material, the tube pipes develop a strong hardness.
As such, the tube bundle has a strong anti-vibration performance and impact the performance of high-temperature steam.
The heat transfer performance is good as the tubes use thin walls which improve the overall heat transfer performance.
Under a similar heat transfer area, the general heat transfer coefficient is 2.124 and 8.408% more than that of copper.
They attract low maintenance costs, and this is because the device often has a longer service life.
With the information in this guide, am sure you can choose the best tube bundle in the market.
In case you have any question about tube bundles, feel free to contact FilSon Filters team.