Understanding your choice of tube sheets options
Tube sheets play a crucial role in the performance and efficiency of heat exchangers and boilers. These components are essential for maintaining the integrity of the tube-to-tube sheet connection, ensuring optimal heat transfer and preventing leakage. At Guanxin, we will delve into the different tube sheet options available, their benefits, and the factors to consider when selecting the ideal tube sheet material and design for your application.
What are tube sheets?
The tube sheet is a round steel plate drilled with holes slightly larger than the outer diameter of the pipe. It is used to fix the pipe and seal the medium in the heat exchanger. An accessory that penetrates, welds, and fixes a pipe to serve this purpose.
The accuracy of tubesheet processing, especially the tolerance of tube hole spacing and diameter, perpendicularity, and finish, greatly affects the assembly and use performance of the chemical equipment listed above.
The Importance of Quality Tube Sheets
Tube sheets are subjected to high pressure and temperature differentials, which can cause mechanical and thermal stresses. These stresses can result in tube sheet failure, leading to equipment shutdowns, safety hazards, and costly repairs.
To prevent these issues, it is crucial to use high-quality tube sheets that are designed to withstand the demands of industrial applications. Quality tube sheets are made from materials that can resist corrosion, erosion, and thermal fatigue. They are also manufactured to precise specifications, ensuring that they fit snugly into the heat exchanger and provide a secure connection for the tubes.
Factors Affecting Tube Sheet Performance
While adherence to standards is crucial for ensuring the quality of tube sheets, there are several other factors that can affect their performance. These factors include:
- Material selection – Tube sheets can be made from various materials, such as carbon steel, stainless steel, and titanium. The material selected must be compatible with the fluids being processed and should be able to withstand the temperature and pressure differentials.
- Design – The design of the tube sheet should consider the number of tubes, their diameter, and their pitch. The design should also allow for easy cleaning and maintenance.
- Fabrication – The fabrication process should ensure that the tube sheet meets the required specifications for dimensions, tolerances, and surface finish. Fabrication techniques such as welding, drilling, and machining should be performed to high standards to avoid defects that could compromise the tube sheet’s performance.
- Inspection – The tube sheet should undergo thorough inspection to ensure that it meets the required standards for quality and performance. Inspection techniques such as ultrasonic testing, radiography, and dye penetrant testing can be used to detect defects such as cracks, porosity, and inclusions.
Advantages of Tube Sheets
Tube sheets come in different thicknesses and dimensions to suit specific heat exchanger designs. Some of the essential features of tube sheets include:
Robust Construction: Tube sheets are designed to withstand extreme temperatures and pressures, making them suitable for various industrial processes.
Corrosion Resistance: The choice of material for tube sheets determines their resistance to corrosion, which is crucial in maintaining their structural integrity and ensuring a longer lifespan.
Customizability: Tube sheets can be tailored to specific heat exchanger designs, making them versatile components that cater to a wide range of applications.
Enhanced Heat Transfer Efficiency: Tube sheets are designed to maximize heat transfer between fluids, providing a more efficient heat exchange process. They enable the optimal arrangement of tubes in a heat exchanger, ensuring that heat is transferred evenly across the entire surface area. This results in lower energy consumption and operating costs, making tube sheets essential in energy-efficient heat exchanger designs.
Ease of Maintenance and Cleaning: The design of tube sheets allows for easy access to tubes, making maintenance and cleaning processes more straightforward. The tube sheet can be easily disassembled, allowing technicians to inspect, clean, and replace tubes. This ensures that heat exchangers maintain peak performance and reduces the likelihood of costly downtime due to equipment failure.
Improved Structural Integrity: Tube sheets are the backbone for heat exchanger designs, providing a sturdy base that supports the tubes and other components. This structural integrity is crucial for maintaining heat exchangers’ overall stability and durability, ensuring they can withstand harsh operating conditions and extreme temperatures without succumbing to damage or failure.
Types of tube sheets
Here are some common types of tube sheets:
Fixed Tube Sheet:
In this type, the tube sheet is welded directly to the shell, and the tubes are attached. This design provides a simple and cost-effective solution. Still, it could be more suitable for applications with large temperature differences between the shell and tube sides, as thermal expansion could lead to stress and potential failure.
Floating Tube Sheet:
A floating tube sheet is not directly attached to the shell, allowing for thermal expansion without causing stress. It is used in applications with significant temperature differences between the shell and tube sides. A floating head or backing device maintains the tube bundle’s position within the shell and ensures proper sealing.
In a U-tube heat exchanger, tubes are bent into a U-shape, with both ends connected to the same tube sheet. This design allows differential thermal expansion without causing stress on the tube sheet or tubes. U-tube heat exchangers are often more compact and can handle higher thermal loads compared to other designs.
Double Tube Sheet:
Double tube sheets are used in applications where cross-contamination between the shell and tube sides must be avoided, such as in the pharmaceutical and food industries. This design features two separate tube sheets, creating an additional barrier to prevent fluid leakage between the two sides.
Clad Tube Sheet:
A clad tube sheet is made by bonding two dissimilar materials: carbon steel and stainless steel or other corrosion-resistant alloys. This design provides a cost-effective solution for applications requiring corrosion resistance while maintaining the strength and durability of the base material.
Removable Bundle Tube Sheet:
The tube bundle can be removed from the shell for maintenance, cleaning, or inspection in this design. This tube sheet type is often used in heat exchangers with a removable channel or bonnet, making it easier to access the tube bundle.
Divided Flow Tube Sheet:
In a divided flow heat exchanger, the tube sheet is designed with partitions to separate the tube side fluid into different flow paths. This design allows more precise control over the heat transfer process and enables the exchanger to handle multiple fluid streams or different operating conditions.
Perforated Tube Sheet:
A perforated tube sheet features holes or slots cut into it, allowing for specific flow patterns or increased turbulence within the shell side. This design can improve heat transfer efficiency by creating more contact between the shell-side fluid and the tubes.
Baffle-Supported Tube Sheet:
In some heat exchanger designs, tube sheets can be supported by baffles spaced along the shell’s length. These baffles help maintain the tube bundle’s position and direct the flow of the shell-side fluid to enhance heat transfer efficiency.
Tapered Tube Sheet:
A tapered tube sheet has varying thicknesses to accommodate stress levels and thermal expansion requirements. Thicker areas provide additional strength and rigidity, while thinner areas allow for more flexibility in response to thermal expansion. This design can benefit applications with significant temperature differences between the shell and tube sides.
Laminated Tube Sheet:
A laminated tube sheet is made by layering multiple thin sheets of material and bonding them together, often using an adhesive or a diffusion bonding process. This design can help reduce stress concentrations and improve resistance to fatigue and corrosion, making it suitable for high-pressure or corrosive applications.
According to the connection structure between the tube plate, the tube box, and the shell, the tube plate can be divided into:
a) The Extension Serving as a Fixed Tube Plate for the Tube Sheet: In this type of connection, the extension serves as a fixed tube plate, which also functions as a tube sheet. This design allows for easy assembly and disassembly of the heat exchanger, making it suitable for applications requiring regular maintenance and cleaning.
b) A Fixed Tubesheet That Is Not Concurrently Used as a Tube Sheet and Is Welded Together with the Shell Side and Tube Side Cylinders: This design features a welded fixed tubesheet to both the shell side and tube side cylinders. It does not function as a tube sheet, providing a more robust and leak-free connection. This type of tubesheet is best suited for applications where pressure and temperature conditions are more demanding.
The tube plate’s use function or purpose further categorizes it into several types:
a) A Fixed Tubesheet of a Fixed Tubesheet Heat Exchanger: This type of tube plate is found in heat exchangers with a fixed tubesheet design. The fixed tubesheet is securely attached to both the shell and tube sides of the heat exchanger, offering a compact and rigid structure. This design is most suitable for applications with moderate temperature and pressure variations.
b) Fixed Tube Sheets and Floating Tube Sheets of Floating Head Heat Exchangers: In floating head heat exchangers, there are two types of tube plates: fixed tube sheets and floating tube sheets. The fixed tube sheet is attached to the shell side, while the floating tube sheet is free to move axially, allowing for thermal expansion and contraction. This design is ideal for applications with significant temperature differences between the shell side and tube side fluids.
c) A Fixed Tubesheet of a U-shaped Tubular Heat Exchanger: In U-shaped tubular heat exchangers, the fixed tubesheet connects the U-shaped tubes to the shell side. This design allows easy cleaning and maintenance since the tube bundle can be removed without dismantling the shell. This type of heat exchanger is suitable for applications with fouling or scaling tendencies.
d) A Double Tubesheet of a Double Tubesheet Heat Exchanger: A double tubesheet heat exchanger features two tubesheets, providing additional safety and protection against leaks. This design is particularly suitable for applications where the process fluids are hazardous or toxic and must be contained to prevent cross-contamination.
e) Thin Tube Plate: A thin tube plate is a lightweight and cost-effective solution for heat exchangers with low-pressure applications. The reduced thickness of the tube plate makes it more susceptible to deformation under pressure, limiting its use in low-pressure environments.
Each of these tube sheet designs has advantages and disadvantages. The most suitable design will depend on the application’s specific requirements, such as temperature, pressure, fluid properties, and maintenance needs.
Standard for tube sheets
At Guanxin, we understand the importance of tube sheets in various industrial applications. Tube sheets are essential components that connect tubes to heat exchangers, boilers, and condensers. These sheets are responsible for ensuring that tubes are held in place, and they serve as a barrier between the tube and shell sides of a heat exchanger.
Given their critical role, tube sheets must meet specific standards to ensure quality and durability.
Several industry standards guide the design and manufacturing process:
- ASME (American Society of Mechanical Engineers) Section VIII: This standard provides guidelines for designing and fabricating pressure vessels, including heat exchangers. It outlines the essential requirements for material selection, thickness calculations, and fabrication methods.
- TEMA (Tubular Exchanger Manufacturers Association) Standards: Focusing specifically on heat exchangers, these standards cover various aspects of design, materials, fabrication, and testing. TEMA Standards provide a comprehensive framework for ensuring optimal heat exchanger performance.
- EN 13445 (European Standard for Unfired Pressure Vessels): This standard applies to pressure vessels, including heat exchangers, used in European markets. It encompasses essential design, material, and fabrication requirements to ensure safety and performance.
Materials of tube sheets
Depending on the specific application requirements, tube sheets are made from a variety of metal materials, including:
|Titanium tube sheet||ASTM B381 / ASME SB381, Titanium Gr. 1, Titanium Gr. 2, Titanium Gr. 4, Titanium Gr. 5, Titanium Gr. 7, ASTM R50250/GR.1| R50400/GR.2 | R50550/GR.3 | R50700/GR.4 | GR.6 |R52400/GR.7 | R53400/GR.12 | R56320/GR.9 |R56400/GR.5|
|Copper tube sheet||T1, T2, C10100, C10200, C10300, C10400, C10500, C10700, C10800, C10910,C10920, TP1, TP2, C10930, C11000, C11300, C11400, C11500, C11600, C12000,C12200, C12300, TU1, TU2, C12500, C14200, C14420, C14500, C14510, C14520, C14530, C17200, C19200, C21000, C23000, C26000, C27000, C27400, C28000, C33000, C33200, C37000, C44300, C44400, C44500, C60800, C63020, C68700, C70400, C70600, C70620, C71000, C71500, C71520, C71640, etc|
|Copper Nickel tube sheet||ASTM / ASME SB 61 / 62 / 151 / 152, Copper Nickel 90/10 (C70600 ), Cupro Nickel 70/30 (C71500), UNS C71640|
|Carbon Steel tube sheet||ASTM/ASME A/SA105 A/SA105N & A/SA216-WCB, DIN 1.0402, DIN 1.0460, DIN 1.0619, Die Steel, ASTM A105 / ASME SA105, A105N, ASTM A350 LF2 / ASME SA350, High Yield CS ASTM A694 / A694 (F52 F56 F60 F65 F70 F80)|
|Stainless Steel tube sheet||ASTM/ASME A/SA182 F304, F304L, F316, F316L, ASTM/ASME A/SA351 CF8, CF3, CF8M, CF3M, DIN 1.4301, DIN 1.4306, DIN 1.4401, DIN 1.4404, DIN 1.4308, DIN 1.4408, DIN 1.4306, DIN 1.4409|
|Alloy Steel tube sheet||ASTM A182 / ASME SA182 F5, F9, F11, F12, F22, F91|
|Hastelloy tube sheet||ASTM B564 / ASME SB564, Hastelloy C276 (UNS N10276), C22 (UNS N06022), C4, C2000, B2, B3, X Tube Sheets|
|Brass tube sheet||3602 / 2604 / H59 / H62 / etc.|
|Inconel tube sheet||ASTM B564 / ASME SB564, Inconel 600, 601, 625, 718, 783, 690, x750 Tube Sheets|
|Monel tube sheet||ASTM B564 / ASME SB564, Monel 400 (UNS No. N04400), Monel 500 (UNS No. N05500)|
|Duplex tube sheet||S31803 / S32205 A182 Gr F51 / F52 / F53 / F54 / F55 / F57 / F59 / F60 / F61|
|Super Duplex tube sheet||S32750 / S32760 A182 Gr F51 / F52 / F53 / F54 / F55 / F57 / F59 / F60 / F61|
|Alloy 20 tube sheet||ASTM B462 / ASME SB462, Carpenter 20 Alloy, Alloy 20Cb-3|
|Aluminium tube sheet||5052 /6061/ 6063 / 2017 / 7075 / etc.|
|Nickel tube sheet||ASTM B564 / ASME SB564, Nickel 200, Nickel 201, Nickel 205, Nickel 205LC|
|Nimonic tube sheet||Nimonic 75, Nimonic 80A, Nimonic 90|
|Other tube sheet material||Tin bronze, Alumunum bronze, Lead bronze|
|Incoloy tube sheet||ASTM B564 / ASME SB564, Incoloy 800, 800H, 800HT (UNS N08800), 825 (UNS N08825), 925 Tube Sheets|
|254 Smo tube sheet||ASTM A182 / ASME SA182, SMO 254/6Mo, UNS S31254, DIN 1.4547|
Selecting the right tube sheet material
- Material selection is crucial when choosing tube sheets for your piping system. Factors to consider include corrosion resistance, temperature, and pressure requirements. Common materials used for tube sheets include:
- Carbon Steel: Offers excellent strength and durability, making it suitable for high-pressure applications.
- Stainless Steel: Provides outstanding corrosion resistance, making it ideal for use in harsh environments or applications where chemical compatibility is essential.
- Alloy Steel: Delivers enhanced resistance to heat and corrosion, making it suitable for high-temperature and high-pressure environments.
- Nickel Alloys: Offer superior corrosion and heat resistance, as well as excellent mechanical properties, making them suitable for use in demanding applications such as aerospace, power generation, and petrochemical industries.
Dimensions of tube sheets
The dimensions of tube sheets, including tube pitch, tube diameter, tube sheet thickness, and hole pattern, play a crucial role in determining shell and tube heat exchangers’ performance, efficiency, and safety. By carefully considering these dimensions, designers can optimize heat transfer efficiency, minimize pressure drop, and ensure the structural integrity and leak prevention of their heat exchanger designs. A thorough understanding of these dimensions is essential for engineers and technicians involved in designing, operating, and maintaining shell and tube heat exchangers.
Tube Pitch – Maximizing Heat Transfer Efficiency
Tube pitch, also known as tube spacing, is the distance between the centerlines of adjacent tubes in a tube sheet. It plays a vital role in determining the heat transfer efficiency and pressure drop across the heat exchanger. A larger tube pitch can increase heat transfer efficiency by allowing more space for the shell-side fluid to flow around the tubes. However, it may also lead to a larger shell diameter and a higher pressure drop. On the other hand, a smaller tube pitch can reduce the pressure drop but may decrease heat transfer efficiency due to the reduced flow area. It is essential to balance these factors when selecting the optimal tube pitch for a specific application.
Tube Diameter – Balancing Heat Transfer and Pressure Drop
The tube diameter is another critical dimension in designing a tube sheet. It directly affects the heat transfer area, the fluid velocity inside the tubes, and the pressure drop across the heat exchanger. A larger tube diameter provides a greater heat transfer area, leading to higher heat transfer efficiency. However, it may also increase the pressure drop and the overall size of the heat exchanger. Conversely, a smaller tube diameter reduces the pressure drop but may compromise heat transfer efficiency. Designers must carefully consider the trade-offs between heat transfer efficiency and pressure drop when selecting an appropriate tube diameter for their applications.
Tube Sheet Thickness – Ensuring Structural Integrity and Leak Prevention
Tube sheet thickness is crucial for maintaining the structural integrity of the heat exchanger and preventing leaks between the shell-side and tube-side fluids. A thicker tube sheet can withstand higher pressure and provide better support for the tubes, ensuring a secure and leak-free connection. However, a thicker tube sheet also increases the weight and cost of the heat exchanger. Designers must consider the operating pressure, tube diameter, and tube pitch when determining the appropriate tube sheet thickness to ensure the reliability and cost-effectiveness of their designs.
Hole Pattern – Optimizing Tube Layout and Flow Distribution
The hole pattern on a tube sheet refers to the arrangement of tubes and the shape of the holes drilled through the tube sheet. Common hole patterns include square, triangular, and rotated square layouts. The hole pattern influences the flow distribution of the shell-side fluid, the heat transfer efficiency, and the pressure drop across the heat exchanger. A well-designed hole pattern ensures uniform flow distribution, minimizing the risk of localized hotspots and uneven heat transfer. It also maximizes the number of tubes fitted into the shell, enhancing heat transfer efficiency. Designers must carefully select the appropriate hole pattern to optimize the performance of their heat exchangers.
Manufacturing process of tube sheets
At Guanxin, we are committed to providing high-quality tube sheets that meet and exceed industry standards. We use state-of-the-art manufacturing processes and inspection techniques to ensure that our tube sheets are of the highest quality and can withstand the demands of industrial applications. Our tube sheets are made from a wide range of materials and are designed to meet the specific requirements of our customers’ applications.
Tube Sheets can be produced by forging, casting. We mainly produce tube sheets by forging, cutting and rolling processes. We will take you through the step-by-step process of manufacturing tube sheets, from the materials used to the final product.
Here is an example of low alloy steel steam generator tube plate forgings recently produced by our company. The steam generator tube plate forgings are low-alloy steel forgings (18MND5) tempered and heat-treated, with a pie-shaped structure and a final forming size of Φ3540mm×845mm, which is the thickest among nuclear capacitor forgings. The manufacturing capability is typical of nuclear capacitor forgings, such as head, top cover, receiver and other forgings. The main manufacturing process of steam generator tube plate forgings is as follows:
Step 1: Raw Material Selection and Preparation
The first step in the manufacturing process of tube sheets is selecting the appropriate raw materials. Tube sheets are typically made of high-quality metals such as carbon steel, stainless steel, and titanium. The selection of the material depends on the specific application and the operating conditions of the equipment.
Once the metal material is selected, it needs to be prepared for further processing. The raw material needs to be inspected for any defects such as cracks, inclusions, or voids. These defects can negatively affect the performance and durability of the tube sheets. Any defective material should be discarded or repaired before the manufacturing process begins.
The raw material is then cut into the desired size and shape using a saw or other cutting tools. The dimensions of the tube sheet should be precise to ensure proper fit and alignment with the tubes. The cut pieces are then cleaned and prepared for the next step in the manufacturing process.
Step 2: Cutting and Shaping the Raw Material
After the raw material is prepared, the next step is to cut and shape it into the desired form. The cutting and shaping process can be done through various methods such as flame cutting, plasma cutting, or water jet cutting. The method used depends on the thickness and type of material being used.
Once the raw material is cut to size, it is shaped to create the necessary contours and holes for the tubes. This can be done through various techniques such as drilling, milling, or punching. The shaping process needs to be precise to ensure proper alignment and fit of the tubes.
Step 3: Forging Process for Tube Sheets
The weight of forging ingot is about 140,000kg, and the forging billet is made by free forging in the way of 10,000 tons hydraulic press, the axis of forging billet is parallel to the axis of ingot, the starting forging temperature is ≤1270℃, the final forging temperature is ≥800℃, the cutting head rate of ingot is ≥22%, the cutting tail rate is ≥9%, the total forging ratio is ≥22, according to RCC-M M380, the calculated total forging ratio must be more than 3. As the maximum wall thickness of the forging billet reaches 900-1000mm, in order to ensure the compaction effect of the center of the plate, the forging process should ensure sufficient deformation, and use a special V-shaped taper plate to ensure the compaction effect of the center of the plate, control the forging pressure and deformation rate, in order to achieve the purpose of uniform refinement of the grain, so as to ensure that the late plate forgings have good ultrasonic penetration.
The forging process is divided into 5 fires in total. In the first fire, the ingot body is drawn to Φ2200mm×3730mm, and the water spout is removed, and a clamp handle is pressed at the end of the spout for easy clamping by the operator, with the size of Φ950mm×1000mm, and the excess is removed. In the 3rd fire, the ingot body is upset to Φ2950mm×2000mm, then it is drawn to Φ1850mm×5100mm by KD method, and the 550mm (including the cutter) is removed from the water mouth end, and then it is discharged to Φ1850mm×3900mm; in the 4th fire, it is upset to Φ2700mm×1800mm; in the 5th fire, it is firstly upset by V-shaped cone plate, then it is rolled to the outer circle. The size of taper plate upsetting and final forging are shown below.
Sketch maps of sizes for upsetting (a) and final forging (b) of V-shape cone plate
Step 4: Heat Treatment of Tube Sheets
After the forging of the tube sheet is completed, it is necessary to carry out a preparatory heat treatment to improve the internal organization and grain size of the forging, eliminate internal stress and prepare for the subsequent performance heat treatment. The normalizing + tempering process is used for the preparatory heat treatment. The normalizing temperature is selected in the range of 900-950°C, followed by air cooling. After normalizing, tempering is carried out at a holding temperature between 620-680°C, followed by air cooling.
After the preparatory heat treatment, the performance heat treatment is carried out. The normalizing + quenching + tempering process is used for the performance heat treatment, and the normalizing holding temperature is selected in the range of 850-950°C, followed by accelerated cooling. Quenching austenitizing heating temperature range of 850-950 ℃, forging from the furnace to enter the quenching and cooling tank time should be controlled within 5min, forging cooling uniform, the final cooling temperature of the forging surface should be less than 80 ℃. Tempering temperature control between 635-665 ℃, followed by air cooling. It should be emphasized that the temperatures mentioned above in the heat treatment process are the forging body temperature, not the furnace chamber temperature, and at least 2 thermocouples are used to contact the forging body, 1 on each of the upper and lower surfaces. The temperature deviation of different parts of the forging in the heat treatment process should be controlled within ±10℃.
After the performance heat treatment of the tube plate forgings, for the mechanical properties of the test material with simulated post-weld heat treatment requirements, should also be a separate simulation of stress relief heat treatment. Simulation of stress relief heat treatment should pay attention to the following points:
- (1) Insulation temperature of 595-625 ℃, insulation time of not less than 16h.
- (2) Temperature above 300 ℃ heating and cooling rate of not more than 55 ℃ – h-1.
- (3) The maximum deviation of holding temperature is ±5℃.
Step 5: Machining the Forged Tube Sheets
After the forging and heat treatment process, the tube sheets are machined to achieve the final dimensions and surface finish. Machining involves using various cutting tools such as drills, lathes, and milling machines to remove excess material and create the necessary contours and holes for the tubes.The machining process of tube sheet forging is mainly divided into roughing, semi-finishing and finishing. The rough machining is mainly for the preparation of the corresponding non-destructive inspection and subsequent heat treatment in the process, and the subsequent semi-finishing and finishing processes after the heat treatment and sampling process. The tube plate profile has a tab structure, and the machining process is mainly a floor boring and milling process. The accuracy of the machining procedure is determined in advance through 3D modeling, shaped surface programming and program trajectory simulation.
Process 1: Roughing, Semi-finishing, and Finishing of the End Face of the Tube Sheet
In this process, the tube sheet’s end face undergoes three stages: roughing, semi-finishing, and finishing. Roughing involves removing excess material to shape the tube sheet. This step is followed by semi-finishing, which further refines the tube sheet’s surface to prepare it for the final stage. Finally, the finishing process ensures a smooth, clean, and accurate surface that meets the required specifications.
The machined tube sheets receive surface treatments to enhance their appearance, corrosion resistance, and performance. Common surface treatments include electroplating, passivation, and painting. The choice of treatment depends on the tube sheet material and the application requirements. After the surface treatment, the tube sheets are cleaned and inspected.
The surface finish of tube sheets is critical in ensuring proper sealing and maintaining the integrity of the connection. The following guidelines should be observed:
- The tube sheet face must be free of defects, such as burrs, scratches, and pits.
- The surface finish of the tube sheet contact face should be in accordance with ASME B46.1, with a maximum roughness average (Ra) of 3.2 μm (125 μin) for raised face tube sheets and 6.3 μm (250 μin) for flat face tube sheets.
Process 2: Drilling of the Tube Sheet
The drilling process involves creating precise holes in the tube sheet according to predetermined measurements and specifications. These holes will accommodate the tubes that will be fitted into the tube sheet. To ensure accuracy and efficiency, the drilling process may be performed using CNC machines, which can drill multiple holes simultaneously and maintain precise spacing between them.
Typical Hole Patterns: The most common types of holes experienced in tube sheet drilling are triangular, rotated triangular, square and rotated square. Each hole pattern presents its own drilling challenges. See typical pattern types below.
Sequence 3: Milling of the Inner Hole Slot of the Tube Sheet
In this sequence, the inner hole slot of the tube sheet is milled to create a groove or channel where the tubes will be seated. This milling operation ensures that the tubes are securely positioned and aligned within the tube sheet. The milling process can be carried out using various milling machines, such as horizontal or vertical milling machines, with the appropriate milling cutters to achieve the desired slot shape and dimensions.
Process 4: Chamfering of the Tube Sheet
The final process involves chamfering the tube sheet, which means creating a beveled edge at the intersection of the holes and the tube sheet’s surface. This step is essential to eliminate sharp edges and facilitate the smooth insertion of tubes into the holes. Chamfering also prevents potential damage to the tubes during installation and ensures a tight seal between the tubes and the tube sheet. This process can be done using chamfering tools or machines, which create a uniform and clean chamfer around each hole.
Process 5: Deburring of the Tube Sheet
Once the chamfering process is complete, it is crucial to remove any remaining burrs or sharp edges from the tube sheet. This process, known as deburring, helps ensure that the tube sheet has a smooth and clean surface, reducing the risk of injury during handling and further processing. Deburring can be performed using manual methods, such as using deburring tools, or automated methods, like utilizing deburring machines or robotic systems.
Step 6: Quality Control and Inspection
Throughout production, the tube sheets undergo rigorous quality control and inspection procedures to ensure they meet the required specifications and industry standards. This includes dimensional checks, non-destructive testing (radiographic, ultrasonic, or magnetic particle testing), and destructive testing (such as tensile, impact, or hardness) to verify the tube sheets’ mechanical properties and integrity. In addition, a visual inspection is performed to assess surface finish, cleanliness, and overall artistry.
Tube plate forgings should be the corresponding nondestructive inspection to determine whether the forgings internal and surface defects, the inspection items are mainly visual inspection, ultrasonic inspection, magnetic particle inspection. The tube plate forgings should be intact, there should be no hairline, crack, cut marks or other harmful defects. After finishing the forgings, 100% full-volume ultrasonic inspection should be carried out in accordance with the requirements of RCC-M M2115, magnetic particle inspection on the non-overlay surface of the tube plate, and penetration inspection on the overlay surface, in order to find out whether there are oversize defects inside and on the surface of the forgings. Pipe plate forgings belong to large wall thickness forgings, ultrasonic testing process in the forgings propagation of ultrasonic waves in the long range, attenuation, therefore, in the selection of ultrasonic inspection equipment, it is appropriate to use high-power ultrasonic flaw detector and the corresponding probe with the use to improve the signal-to-noise ratio.
In the physical and chemical inspection, pipe plate forgings should be room temperature tensile, 350 ℃ high temperature tensile, KV impact test, drop hammer test, chemical analysis and metallurgical inspection (including microstructure observation, grain size and non-metallic inclusions), etc.. Should be in the performance heat treatment, performance heat treatment + simulation of post-weld heat treatment after cutting specimens, respectively. Forging mechanical properties results should meet the requirements. Mechanical properties test results failed in accordance with RCC-M M2115 section 4.4 of the provisions of the heat treatment again.
Metallographic inspection of the tube plate simulations, including grain size and non-metallic inclusions test. Among them, the grain size test should be in the performance heat treatment and simulation of post-weld heat treatment, in accordance with the requirements of RCC-M M2115 section 3.5, grain size shall not be less than 5. Non-metallic inclusions according to GB/T10561-2005 A method of assessment, the results meet the requirements. In addition, should also be in accordance with the RCC-M M2115 Appendix 1 test method for the drop hammer test to determine the material without plastic transformation temperature RTNDT ≤ -20 ℃.
The defects of the tube plate forgings are not allowed to be excavated and patched, but the defects can be removed by grinding, and the dimensions of the forgings are still within the specified tolerance after grinding before acceptance, and the magnetic particle inspection shall be carried out according to the provisions of RCC-M MC5000 after repair.
The forging process must ensure sufficient deformation and the total forging ratio calculated according to RCC-M M380 must be greater than 3. The actual total forging ratio of this production must be greater than 22 due to the thickness of the forging billet to ensure the forging effect of the center of the tube plate forging, the use of special V-shaped vertebrae to ensure the deformation of the center of the tube plate, and at the same time to control the forging pressure and deformation rate to achieve uniform refinement of grain. Purpose. After forging, initial heat treatment and performance heat treatment should be carried out for the mechanical properties of the test material with the requirements of the simulated post-welding heat treatment; there should also be a separate simulation of stress relief heat treatment. After finishing the forging, 100% full-volume ultrasonic inspection should be performed by the requirements of RCC-M M2115, magnetic particle inspection on the non-overlay surface of the tube plate, and penetration inspection on the overlay surface to find out whether there are oversize defects inside and on the surface of the forging. In addition, it should also be by RCC-M M2115 and the requirements of GB/T10561-2005 room temperature tensile, 350 ℃ high temperature tensile, KV impact test, drop hammer test, chemical analysis and metallurgical testing, and other physical and chemical tests, should be in the performance heat treatment and performance heat treatment + simulation of post-weld heat treatment after cutting specimens, respectively. When the mechanical performance test results fail, the heat treatment can be repeated by the provisions of section 4.4 of RCC-M M2115. The steam generator tube plate forgings with various indexes meeting the relevant standards and technical conditions are successfully manufactured by controlling the manufacturing points of each critical process link above.
Step 7: Marking
The marking of tube sheets is essential to their manufacture and use. The marking aims to provide information about the tubesheet’s material, size, pressure rating, and other relevant details.
The required information typically includes the following:
- Manufacturers trademark or name;
- Material Designation;
- Rating Designation;
- Size Designation;
- Product Heat Numbers ;
- Tube sheet design model.
The standard also specifies the location of the marking on the tube sheet. Typically, the marking is placed on the raised face of the tube sheet near the bolt holes. In some cases, the marking may be located on the tube sheet hub or the plate itself.
Step 8: Packaging
Packaging is an important step in the manufacturing process of tube sheets. Proper packaging helps to protect the tube sheets from damage during transportation and storage.
The tube sheets are carefully packaged using materials such as bubble wrap, foam, or cardboard to prevent any damage during transportation. The packaging process also includes securing the tube sheets to prevent any movement or shifting during transportation.
Step 9: Transportation
Transportation is the final step in the manufacturing process of tube sheets. The tube sheets are transported to the customer or to a storage facility for later use.
The transportation process needs to be carefully planned to ensure that the tube sheets are delivered on time and in good condition. The tube sheets are typically transported using trucks, ships, or planes, depending on the distance and location of the customer.
The manufacturing process of tube sheets is a complex process that requires precise techniques and high-quality materials to ensure optimal performance and durability. The Complete Guide to Manufacturing Tube Sheets provides a comprehensive resource for engineers, manufacturers, and technicians involved in the production of tube sheets.
In this book, we have covered every aspect of the tube sheet manufacturing process, from raw material selection and preparation to transportation. By following the guidelines provided in this book, you can ensure that your tube sheets are of the highest quality and meet industry standards.
Assembly and Integration Tube Sheet
Once the tube sheet has passed inspection and received any necessary surface treatments, it is ready to be assembled and integrated into the heat exchanger or pressure vessel. This process involves inserting the tubes into the holes of the tube sheet and securing them using various methods, such as expansion, welding, or brazing. The tube sheet, along with the tubes, is then assembled with other components of the heat exchanger or pressure vessel, ensuring proper alignment and sealing to prevent leaks and maintain optimal performance.
By following these processes, the tube sheet is fabricated, inspected, and integrated into the heat exchanger or pressure vessel, contributing to the overall efficiency and reliability of the system.
Application of tube sheets
Tube plate is widely used in column tube heat exchanger, boiler, pressure vessel, turbine, large central air conditioning, and other industries.
This tube sheet is used in various industries:
Tube Sheets used in Oil and Gas Pipelines;
Tube Sheets used in Chemical Industry;
Tube Sheets used in Plumbing;
Tube Sheets used in Heating;
Tube Sheets used in Water Supply Systems;
Tube Sheets used in Power Plants;
Tube Sheets used in the Paper & Pulp Industry;
Tube Sheet uses in General Purpose Applications;
Tube Sheets used in Fabrication Industry;
Tube Sheet uses in Food Processing Industry;
Tube Sheets Use in Structural Pipe.
How to purchase the correct tube sheets?
- Flat face (FF): This type of tube sheet face has a flat, smooth surface that is perpendicular to the axis of the pipe. It is typically used for low-pressure applications and when the sealing is achieved by a gasket.
- Raised face (RF): This type of tube sheet face has a raised ring on the surface that surrounds the bolt holes. The ring provides a surface for the gasket to rest on, which helps to create a better seal. It is commonly used in applications with moderate pressure.
- Ring joint face (RTJ): This type of tube sheet face has a specially designed groove to accommodate a metallic ring gasket. The groove is cut into the surface of the tube sheet, and the gasket sits in the groove to create a tight seal. This type of tube sheet face is typically used in high-pressure applications.
Once you have identified the material and tube sheet type, the next step is to determine the size and pressure class of the tube sheet. tube sheets are available in various sizes and pressure ratings, and it’s crucial to select the correct size and pressure class to ensure that the tube sheet can withstand the intended operating conditions. You should consult the system specifications and design to determine the appropriate size and pressure class.
The tube sheet face’s surface finish directly impacts the seal’s quality between the tube sheets. Common surface finishes include smooth, serrated, and grooved. Consult with the gasket manufacturer and consider the specific requirements of your application to select the most appropriate surface finish for your tube sheets.
How to select tube sheets manufacturer?
Choosing the right tube sheets manufacturer is essential to ensure you get high-quality products that meet your needs. Look for a manufacturer with quality certifications, experience, a good reputation, customization capabilities, and a competitive price. By following these tips, you will be able to find the right manufacturer for your tube sheet needs.
Why Choose Guanxin to Be Your Tube Sheet Supplier?
Guanxin is a well-established and reputable manufacturer and supplier of tube sheets that has been providing high-quality products to customers worldwide for many years. Here are some reasons why you might choose Guanxin to be your tube sheet supplier:
- High-quality products: Guanxin is committed to providing high-quality tube sheets made from the best materials and manufactured to the highest standards. The company has strict quality control procedures in place to ensure that each product meets or exceeds customer expectations.
- Competitive pricing: Guanxin offers competitive pricing on its products, which means you can get high-quality tube sheets at an affordable price.
- Wide range of products: Guanxin offers a wide range of tube sheets, including ANSI, DIN, JIS, EN, and other international standards. This means you can find the right product to meet your specific needs.
- Excellent customer service: Guanxin is committed to providing excellent customer service and support to all of its customers. The company has a team of experienced professionals who are available to answer any questions or concerns you may have.
- Fast delivery: Guanxin understands the importance of timely delivery and works hard to ensure that all orders are shipped out quickly and efficiently.
Export Country For Tube Sheets
|MIDDLE EAST||AFRICA||NORTH AMERICA||EUROPE||ASIA||SOUTH AMERICA|
|Oman||Sudan||Trinidad And Tobago||Spain||South Korea||Ecuador|
|Turkey||The Republic Of Congo||Bahamas||Netherland||Sri Lanka||Paraguay|
5. Structural forms of connection between heat exchanger tubes and tubes plates
Tube and tube plate connection, in the design of shell and tube heat exchanger, is a relatively important part of the structure. It is not only a large processing workload, and must make each connection in the operation of the equipment, to ensure that the medium without leakage and the ability to withstand media pressure.
For the tube and tube plate connection structure form, there are three main: (1) expansion, (2) welding, (3) expansion welding combination. These forms in addition to the characteristics inherent in the structure itself, in the processing, production conditions, operating techniques have a certain relationship.
1. Expansion joint
Used in the case of leakage of media between the tube and shell will not cause adverse consequences, expansion of the structure is simple, easy to repair the tube. Due to the plastic deformation of the expansion joint at the end of the expansion joint, there is a residual stress, as the temperature rises, the residual stress gradually disappears, so that the end of the tube to reduce the role of sealing and bonding. So this expansion structure, subject to certain restrictions on pressure and temperature. Generally applicable pressure P0 ≤ 4MPa, the limit of residual stress disappearance at the end of the tube temperature varies with the material, carbon steel, low alloy steel when the operating pressure is not high, the operating temperature can be up to 300 ℃. In order to improve the quality of the expansion, the hardness of the tube plate material requires higher than the hardness of the tube end, so as to ensure the strength and tightness of the expansion joint.
For the roughness of the bonding surface, the size of the pore between the tube hole and the tube, the quality of the expanded tube also has a certain impact, such as the bonding surface rough, can produce greater friction, expansion is not easy to pull off, if too smooth is easy to pull off, but not easy to produce leakage, the general roughness requirements for Ra12.5. In order to ensure that the bonding surface does not produce leakage phenomenon, in the bonding surface does not allow the existence of longitudinal groove marks.
Pipe hole with light hole and ring groove hole, the form of the hole and expansion strength, the expansion of the mouth by the pull-off force is small, can be used in the light hole, in the pull-off force is larger when the structure with ring groove.
Light hole structure for the material properties of the heat exchanger, the expansion depth of the tube plate thickness minus 3mm, when the thickness of the tube plate is greater than 50mm, the expansion depth e generally take 50mm, tube end extension length of 2-3mm.
When the expansion joint, the tube end will be expanded into a conical shape, due to the role of the flap, can make the tube and tube plate combined more firmly, higher resistance to pull off the force. When the tube bundle is subjected to compressive stress, the structural form of flanging is not used.
The purpose of slotting the pipe hole is similar to that of flanging the pipe mouth, mainly to improve the resistance to pull-off force and enhance the sealing. The structural form is to open a small circular slot in the pipe hole, the depth of the slot is generally 0.4-0.5mm, when the expansion, the pipe material is squeezed into the slot, so the medium is not easy to leak. The number of slots in the pipe hole depends on the thickness of the pipe plate, when the plate is less than 30mm, open a slot, the thickness of the plate ≥ 30mm, open two slots.
The expansion depth is decided by full expansion type and non-expansion type, for the tube plate using not full expansion type, when the thickness of the tube plate is greater than 50mm, the expansion depth is still 50mm.
The tube plate is composite steel plate, slotting position is divided into two cases, when the cladding is thin, slotting position are on the grass-roots level, such as thicker cladding, then a slot can be opened on the compound layer, but not allowed to slot between the cladding and the grass-roots level.
The welding of pipe and pipe plate is widely used at present, because the pipe hole does not need to be slotted, and the roughness of the pipe hole is not required, and the pipe end does not need to be annealed and polished, so it is easy to manufacture and process. Welded structure of high strength, strong resistance to pull off, when the welded part of the leakage, you can make up the welding, such as the need to exchange the tube, you can use a special tool to disassemble the welded leaky tube, but more convenient than the disassembly of the expansion tube.
Tube and tube plate welding, the shear section of the weld should be no less than 1.25 times the section of the tube.
Stainless steel tube and tube plate, generally using a welded structure, regardless of its pressure and temperature. In order to avoid fluid stagnation on the tube plate after parking, and to compensate for the special situation of pressure loss at the entrance of the tube, reduce the resistance of the orifice, the tube can be shrunk in a certain position inside the tube plate hole, but this structure welding technology requirements are high, generally need to use automatic argon arc welding machine, the quality can be guaranteed, the orifice is easy to block in the welding process, especially for small diameter tubes, in welding should draw attention to. Sometimes in order to reduce the welding stress, you can process a concave groove surface down at the orifice of the tube plate, the structure is generally used for stainless steel and tube plate welding. Grooves around the pipe hole, processing trouble, workload, in the current construction has been groove leather.
3. Expansion welding combination
For high pressure, strong permeability, or corrosive media on one side, in order to ensure that no leakage after contamination of the other side of the material, which requires absolute non-leakage of the connection between the tube and the tube plate, or in order to avoid the impact of vibration on the weld during shipment and operation, or to avoid the possibility of seam corrosion, etc.
The structure of the expansion and welding combination, from the process of processing, there are several forms of expansion and then welding, welding and then expansion, welding and then expansion and paste expansion.
Expand first and then weld, expand the tube before welding, can improve the performance of the weld fatigue resistance, because the expansion of the tube to avoid tightly on the tube plate hole wall, can prevent cracks in the welding. But in the expansion of the tube due to the use of lubricating oil and into the gap of the joint, the presence of these residual oil and air in the gap heat expansion and vaporization, in the process of welding the joint under the action of high temperature to generate gas, escaping from the welding surface, resulting in the weld pores, seriously affecting the quality of the weld, so these residual oil must be cleaned off before welding.
First weld after expansion: the use of first weld after expansion can eliminate the above phenomenon, but the use of first weld after expansion may make the weld cracking during expansion. In order to prevent this phenomenon, in addition to the expansion of the operation is carefully controlled properly, in the end of the tube, that is, in the first slot from the surface of the tube plate distance to be considered larger, about 16mm, in the range of 10-12mm from the surface of the tube plate is not expanded to avoid damage to the weld when expanding the tube. The advantage of first welding and then expanding is that it is not necessary to clean up the oil residue after expansion, but the requirements for the location of the expanded pipe after welding are high, and it must be ensured that no expansion is carried out within the range of 10-12mm, otherwise the weld is easily damaged.
First expansion after welding or first welding after expansion, for the welding part: there is a difference between sealing welding and strength welding two forms of welding, for the expansion part, there is a difference between strength expansion and paste expansion. Such as expansion and sealing welding combined with the structure, is to expand the joint to withstand the force, and sealing welding to ensure the sealing. Seal welding height is generally 1-2mm, so as not to affect the strength of the expansion joint, but in the welding must be cleaned at the joint of oil. Strength welding and expansion (paste expansion) combined with the structure, is to weld to withstand the force, while the purpose of paste expansion is only to eliminate the gap between the tube and the tube plate, in order to prevent the gap from having corrosive media erosion.
After welding expansion and paste expansion: After welding expansion and paste expansion is generally used in higher pressure heat transfer equipment, the welding part of the strengthening seal welding, welding waist height using 2.8mm, expansion part of the force, when the expansion failure, strengthening seal welding can play a role in bearing the force, paste expansion part of the gap to eliminate corrosion.
Weld expansion of the structure in what conditions, using the first weld after expansion or expansion after welding, there is no uniform provisions, but generally tend to first weld after expansion is appropriate. At present, because of the manufacturing plant plus process, equipment conditions are different, are accustomed to the plant’s production methods.
4. Bore welding
Inner hole welding is the tube hole in the shell process side of the formation is butt structure, heat exchanger tube with its butt welding, need special welding equipment. Inner hole welding is the tube plate after processing and heat exchanger tube to form a butt weld form, to have special equipment, the welding gun from the tube plate side of the tube hole deep into the welding seam for welding (from the original cross-joint into a butt joint), optimize the stress state of the heat exchanger tube and tube plate connection, greatly reducing the edge stress. It is very practical for heat exchangers with stress corrosion, or interstitial corrosion media.
However, bore welding requires a high and difficult level of welding technology, and the appearance of welding defects cannot be repaired, which can lead to the scrapping of the entire heat exchanger. To ensure that the welding qualified, you need to strictly follow the construction process parameters for welding, testing, etc.
5. Explosive expansion joint
Tube and tube plate connection using explosive expansion method has been used in foreign countries, which is a new process developed in recent years, due to the use of explosive expansion plus sealing welding or strength welding method, not only the connection strength is high, and expansion efficiency has been greatly improved. Explosive expansion without lubricating oil, no oil at the end of the pipe exists, there are great benefits to welding after expansion.
Explosive expansion is the use of explosives, in a very short period of time, the tube in the role of high-pressure gas shock wave, deformation, so that the tube avoid firm tightly on the tube plate hole. Explosive expansion joint is suitable for thin-walled tubes, thick-walled small diameter tubes and large thickness of the expansion of the pipe plate. The advantage of the explosion expansion joint is the resistance to pull off the force, the tube axial elongation and deformation is small, when the tube end of the tube leakage, in can not be repaired with mechanical expansion, the use of explosive expansion joint for repair effect is very good.