Understanding your choice of baffle plates options
When optimizing industrial processes, there are many factors to consider. One of the most critical aspects is the design of the equipment, especially the baffle plate. Baffles are important components that help promote efficient mixing and heat transfer in various industrial applications.
Choosing the right baffle plate for your needs is an important decision that will significantly impact your equipment’s performance. By understanding the different types of baffles and their advantages and disadvantages, you can make an informed choice based on your specific needs.
There are several factors to consider when selecting a baffle plate for your application. These include the vessel’s or pipe’s size and shape, desired flow and heat transfer rates, and any specific operational requirements or challenges.
At Guanxin, we work closely with our customers to understand their unique needs and recommend the best baffle plate option for their application. Our team of experts has years of industry experience and can provide customized solutions to meet the most challenging requirements.
What is a baffle plate?
A baffle plate, as the name implies, is used to change the fluid flow direction of the plate, commonly used in shell and tube heat exchanger design shell process media flow path, according to the nature of the media and flow and heat exchanger size to determine the number of the baffle plate.
Function of baffle plate
The function of the baffle plate is to increase the flow rate and turbulence of the fluid in the shell side, improve heat transfer efficiency, increase the heat transfer coefficient of the fluid in the shell side, reduce fouling, and support the heat exchange tube. They serve to:
Maximize heat transfer: By strategically directing the fluid flow, baffle plates enhance contact with heat transfer surfaces, increasing overall efficiency.
Minimize pressure drop: Properly designed baffle plates reduce pressure loss, resulting in lower energy consumption and operating costs.
Prevent vibration and tube wear: Baffle plates provide structural support to the tubes and minimize vibration, thus extending equipment lifespan and reducing maintenance costs.
The Importance of Baffle Plates
Shell and tube heat exchanger performance are good; the folded plate is very important.
Shell and tube heat exchangers consist of a shell, heat transfer tube bundle, tube plate, baffle plate (baffle) and tube box, and other components. Among them, the baffle plate on the heat transfer efficiency and performance of the heat exchanger has a significant impact, and the baffle plate is diverse; each has its advantages, their form, height, and spacing are different, and the overall performance of the heat exchanger is different, the following shell and tube heat exchanger manufacturer for you to explain specifically:
1. The impact of the height of the baffle plate gap
The bow-shaped baffle plate is the most widely used structure; the notch chord height should be 0.20 – 0.45 times the inner diameter of the shell process cylinder. The notch height of the baffle plate will change the flow state of the fluid, which in turn affects the heat transfer efficiency.
It is found that: the pressure drops and heat transfer coefficient of the shell process decrease with the increase of the height of the notch of the baffle plate. Folded plate vertical notch heat exchanger shell heat transfer coefficient is the largest, horizontal notch heat transfer coefficient is the smallest; 45 ° notch shell pressure drop is the largest, vertical notch shell pressure drop is the smallest.
2. The impact of the baffle plate spacing
The minimum spacing of the baffle plate should be not less than 1/5 of the inner diameter of the shell and not less than 50 mm; the baffle plate at both ends of the bundle should be arranged as far as possible in the shell process inlet and outlet receiver, other baffle plates should be arranged at equal intervals.
The smaller the baffle plate spacing, the greater the self-vibration frequency of the heat exchanger tube, the greater the pressure drop in the shell process, and the higher the heat transfer efficiency.
It is found that the pressure loss of a spiral baffle plate is less than that of a bow-shaped baffle plate structure, the flow rate increases, and the heat transfer coefficient of the spiral baffle plate and bow-shaped baffle plate structure increases. The larger the spacing of the baffle plate shell process heat transfer coefficient is smaller, the smaller the pressure drop.
3. Influence of baffle plate structure form
Common baffle plate structure form bow-shaped baffle plates, spiral baffle plates, disc-ring-shaped baffle plates, and fan-shaped baffle plates. Different baffle plate structures, heat exchanger flow, and heat transfer performances are also different.
Research has found that: the shell process heat transfer coefficient and all-around performance of the spiral plate heat exchanger is higher than the bow-shaped plate heat exchanger, and bow-shaped plate heat exchanger shell process pressure loss is greater than the spiral plate heat exchanger. The spiral plate heat exchanger in the shell process velocity distribution is more uniform.
Under the same conditions, the fan-shaped baffle plate heat exchanger in the most reasonable pressure distribution, disc-circular baffle plate heat exchanger speed distribution is more uniform, which is conducive to slowing down the equipment vibration wear, and bow-shaped baffle plate heat exchanger temperature range changes.
4. Baffle plate material selection and manufacturing
Although the baffle plate generally does not consider the corrosion margin, the selection of inappropriate materials will also affect the use of heat exchangers. For example, the baffle plate material in the low-temperature environment of the toughness and brittle change, the baffle plate material creep at high temperatures, and the baffle plate, media, and heat exchanger tube electrochemical corrosion between the baffle plate can cause damage.
Baffle plate processing and manufacturing, to prevent damage to the outer surface of the heat exchanger tube, baffle plate holes are required to chamfer and grind burrs. To facilitate the penetration of the tube to ensure concentricity, the folded plate, support plate, tie rod holes, etc., should be drilled together. At the same time, the drilling direction should be consistent with the direction of the penetration of the tube.
Types of baffle plates
Different types of baffle plates are used depending on the application and the type of equipment. We will examine the different types of baffle plates, their functions, and their applications.
Segmental Baffles: Maximizing Heat Transfer Efficiency
Segmental baffles are one of the most commonly used types of baffle plates in shell and tube heat exchangers. They are designed to increase fluid flow turbulence, resulting in a higher heat transfer coefficient. They are typically installed staggered, creating a zig-zag flow pattern that promotes effective heat exchange. Single-segmental and double-segmental baffles are both popular variations of this type.
Single-Segmental Baffles: Optimal Performance for Smaller Heat Exchangers
Single-segmental baffles are a widely used type of segmental baffle, consisting of a single cut segment positioned on either side of the shell. These baffles are ideal for smaller heat exchangers, where space limitations require a compact design. Using single-segmental baffles reduces pressure drop and maintains good heat transfer efficiency, making them a popular choice in various industries.
Double-Segmental Baffles: Enhanced Heat Transfer for Larger Applications
Double-segmental baffles are another variation of segmental baffles, featuring two cut segments on each side of the shell. This design offers increased heat transfer efficiency and reduced pressure drop, making them ideal for larger heat exchangers. Their enhanced performance is particularly well-suited for applications with high fluid velocities or requiring greater heat transfer rates.
Orifice Baffles: Controlling Fluid Flow and Pressure
Orifice baffles are designed to control fluid flow and pressure within the heat exchanger. They consist of a series of orifices, or openings, in the baffle plate, which allow the fluid to pass through at a controlled rate. By adjusting the size and number of orifices, engineers can fine-tune the fluid flow and pressure within the exchanger to optimize performance.
Rod Baffles: An Alternative to Traditional Baffle Designs
Rod baffles are a unique alternative to traditional baffle plates, consisting of a series of parallel rods that run the length of the shell. This design promotes a more uniform fluid flow across the tubes, improving heat transfer efficiency and reducing pressure drop. Rod baffles are particularly well-suited for applications with high fluid velocities or where fouling is a concern.
Helical Baffles: A Continuous Flow Solution
Helical baffles are designed to create a continuous, spiral fluid flow through the heat exchanger. This flow pattern increases the turbulence and heat transfer efficiency while reducing pressure drop and fouling. Helical baffles are ideal for applications where continuous flow is required or where a compact design is necessary.
Grid Baffles: Enhancing Heat Transfer in Cross-Flow Exchangers
Grid baffles are an innovative solution for cross-flow heat exchangers, where fluid flows perpendicular to the tube bundle. These baffles have a grid-like structure that promotes turbulence and enhances heat transfer efficiency. Grid baffles are often used in applications with limited space, or a compact, high-performance design is required.
Longitudinal Flow Baffles: Improved Performance for Long Tube Exchangers
Longitudinal flow baffles are designed to promote fluid flow parallel to the tube bundle in shell and tube heat exchangers. This arrangement minimizes pressure drop and reduces the risk of tube vibration, making it ideal for heat exchangers with long tubes or high fluid velocities. Longitudinal flow baffles are commonly used in the petrochemical and power generation industries.
Impingement Baffles: Protecting Tubes from Erosion and Vibration
Impingement baffles are designed to protect tubes from erosion and vibration caused by high fluid velocities. They consist of a perforated plate or a series of rods that intercept the fluid flow, reducing the impact of the fluid on the tubes. This design helps extend the tubes’ life and maintain the heat exchanger’s overall performance.
Support/Blanking Baffles: Reinforcing and Redirecting Fluid Flow
Support baffles, also known as blanking baffles, reinforce the tube bundle structure and redirect fluid flow in shell and tube heat exchangers. They consist of a solid plate with no cutouts, ensuring the tubes are well-supported and the fluid is effectively redirected. Support baffles are typically installed at the inlet and outlet of the heat exchanger or in between segmental baffles for added stability.
Deresonating (Detuning) Baffles: Reducing Tube Vibration and Noise
Deresonating baffles, also known as detuning baffles, are designed to reduce tube vibration and noise in shell and tube heat exchangers. They work by altering the natural frequency of the tubes, preventing resonance and subsequent vibration. This reduces the risk of tube failure and minimizes noise levels, making deresonating baffles a valuable addition to heat exchangers in sensitive environments.
Disk and Doughnut Baffles: Versatile Solutions for a Range of Applications
Disk and doughnut baffles are versatile baffle designs that can be used in various heat exchanger applications. Disk baffles consist of a solid, circular plate with a central hole, while doughnut baffles feature a ring-shaped design with an open center. Both baffles effectively promote turbulence and enhance heat transfer efficiency, with the choice between the two largely dependent on the application’s specific requirements.
Spiral baffle plate
The idea of a spiral baffle is based on the idea that by changing the arrangement of the baffle on the shell side, the fluid on the shell side can flow in a continuous spiral shape. Therefore, the ideal arrangement of the baffle plate should be a continuous spiral surface. However, the spiral surface is difficult to process, and it is also difficult to realize the cooperation between the heat exchanger tube and the baffle plate. Considering the convenience of processing, a series of fan-shaped flat plates (called spiral baffle plates) are used instead of curved surfaces to form an approximate spiral surface on the shell side so that the fluid on the shell side produces an approximate continuous spiral flow. Generally speaking, for processing reasons, a pitch of 24 baffle plates, adjacent baffle plates between the continuous lap and staggered lap two ways, according to the flow channel, can be divided into a single spiral and double spiral, two kinds of structure.
Single Spiral Baffle Plate
A single spiral baffle plate consists of a continuous, helical-shaped plate that runs the length of the heat exchanger shell. It is designed to create a single flow path for the fluid, which flows in a spiral pattern from one end of the heat exchanger to the other.
Double Spiral Baffle Plate
Double spiral baffle plates are separate, helical-shaped plates installed parallel within the heat exchanger shell. They create two independent flow paths for the fluid, which flow in opposite directions.
The basic principle of the spiral baffle plate
The most common application of the traditional heat exchanger is the bow-shaped baffle plate; due to the existence of resistance to flow and pressure drop, there is a flow hysteresis zone, easy to scale, the average temperature difference between the heat transfer is small, vibration conditions prone to failure and other defects, in recent years, gradually replaced by the spiral baffle plate. The ideal spiral folded plate should have a continuous spiral surface. Because of the processing difficulties, the baffle plate, generally by several 1/4 of the fan-shaped flat plate instead of the surface connected, forms an approximate spiral surface. The fluid is in the approximate spiral flow state in the folded flow. Compared with the bowed baffle plate, such a baffle plate (known as a discontinuous spiral baffle plate) can reduce the pressure drop by about 45% under the same conditions. At the same time, the total heat transfer coefficient can be increased by 20%-30%, and the heat exchanger size can be greatly reduced under the same heat load.
Understanding the different types of baffle plates and their respective applications is essential for optimizing the performance of shell and tube heat exchangers. From segmental baffles to deresonating baffles, each design offers unique benefits that can be tailored to suit the needs of a wide range of industries and applications. By selecting the appropriate baffle plate type, engineers can ensure efficient and reliable heat transfer performance in their heat exchanger systems.
Notch of the baffle plate
Baffle platee bow notch height should make the fluid through the gap and lateral flow through the tube bundle flow rate is similar, generally take the notch height h for the nominal diameter of the shell 0.2-0.45, often taken h = 0.2Di. Baffle platee should generally be arranged at equal intervals, the tube bundle at both ends of the folded plate should be as close as possible to the shell process inlet, outlet receiver, the minimum spacing of the folded plate should not be less than 1/5 of the inner diameter of the cylinder, and not less than 50mm, the maximum spacing should not be greater than the cylinder diameter
Bow-shaped baffle plate arrangement is also important in the horizontal heat exchanger, the baffle plate gap should be up and down the horizontal arrangement, if the shell fluid for the gas, and contains a small amount of liquid, the gap should be opened at the lowest point of the baffle plate in order to discharge the liquid, as shown in the figure below (a); if the shell fluid for the liquid, and which contains a small amount of gas, the gap should be opened at the highest point of the baffle plate venting, as shown in the figure below (b). (b) shown below; when the shell process medium for gas, liquid coexistence or liquid containing solid materials, the baffle plate should be left, right vertical distribution, and open the liquid port at the lowest part of the baffle plate, as shown in the figure (c) below.
Gap arrangement of baffle plate
Standard for baffle plates
Different industries have unique requirements for baffle plates, and as such, there are several industry-specific standards to ensure optimal performance:
- ASME (American Society of Mechanical Engineers): ASME is a widely recognized standard in the engineering and manufacturing sectors, providing guidelines for baffle plate design, materials, and fabrication.
- TEMA (Tubular Exchanger Manufacturers Association): TEMA standards are specifically tailored to heat exchanger baffle plates, covering essential aspects such as design, manufacturing, and inspection.
- API (American Petroleum Institute): The API standards cater to the oil and gas industry, addressing critical factors such as corrosion resistance, pressure ratings, and performance in extreme conditions.
Benefits of Adhering to Baffle Plate Standards
Implementing and adhering to baffle plate standards come with numerous benefits, including:
Improved performance: By following industry standards, baffle plates can optimize heat transfer efficiency and reduce pressure drop, leading to better overall performance.
Extended equipment lifespan: High-quality baffle plates reduce wear and tear on tubes, preventing premature failure and extending the life of your equipment.
Reduced maintenance costs: With enhanced durability and performance, baffle plates that adhere to standards require less maintenance, saving both time and resources.
Enhanced safety: By ensuring that baffle plates meet stringent industry standards, the risk of equipment failure, leaks, and accidents is significantly reduced, promoting a safer work environment.
Materials of baffle plates
Depending on the specific application requirements, baffle plates are made from a variety of metal materials, including:
|Titanium baffle plate||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 baffle plate||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 baffle plate||ASTM / ASME SB 61 / 62 / 151 / 152, Copper Nickel 90/10 (C70600 ), Cupro Nickel 70/30 (C71500), UNS C71640|
|Carbon Steel baffle plate||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 baffle plate||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 baffle plate||ASTM A182 / ASME SA182 F5, F9, F11, F12, F22, F91|
|Hastelloy baffle plate||ASTM B564 / ASME SB564, Hastelloy C276 (UNS N10276), C22 (UNS N06022), C4, C2000, B2, B3, X Baffle Plates|
|Brass baffle plate||3602 / 2604 / H59 / H62 / etc.|
|Inconel baffle plate||ASTM B564 / ASME SB564, Inconel 600, 601, 625, 718, 783, 690, x750 Baffle Plates|
|Monel baffle plate||ASTM B564 / ASME SB564, Monel 400 (UNS No. N04400), Monel 500 (UNS No. N05500)|
|Duplex baffle plate||S31803 / S32205 A182 Gr F51 / F52 / F53 / F54 / F55 / F57 / F59 / F60 / F61|
|Super Duplex baffle plate||S32750 / S32760 A182 Gr F51 / F52 / F53 / F54 / F55 / F57 / F59 / F60 / F61|
|Alloy 20 baffle plate||ASTM B462 / ASME SB462, Carpenter 20 Alloy, Alloy 20Cb-3|
|Aluminium baffle plate||5052 /6061/ 6063 / 2017 / 7075 / etc.|
|Nickel baffle plate||ASTM B564 / ASME SB564, Nickel 200, Nickel 201, Nickel 205, Nickel 205LC|
|Nimonic baffle plate||Nimonic 75, Nimonic 80A, Nimonic 90|
|Other baffle plate material||Tin bronze, Alumunum bronze, Lead bronze|
|Incoloy baffle plate||ASTM B564 / ASME SB564, Incoloy 800, 800H, 800HT (UNS N08800), 825 (UNS N08825), 925 Baffle Plates|
|254 Smo baffle plate||ASTM A182 / ASME SA182, SMO 254/6Mo, UNS S31254, DIN 1.4547|
Selecting the right baffle plate material
- Material selection is crucial when choosing baffle plates for your piping system. Factors to consider include corrosion resistance, temperature, and pressure requirements. Common materials used for baffle plates 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 baffle plates
The dimensions of baffle plates, including tube pitch, tube diameter, baffle plate 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 baffle plate. 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 baffle plate. 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.
Baffle Plate Thickness – Ensuring Structural Integrity and Leak Prevention
Baffle Plate 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 baffle plate can withstand higher pressure and provide better support for the tubes, ensuring a secure and leak-free connection. However, a thicker baffle plate 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 baffle plate thickness to ensure the reliability and cost-effectiveness of their designs.
Hole Pattern – Optimizing Tube Layout and Flow Distribution
The hole pattern on a baffle plate refers to the arrangement of tubes and the shape of the holes drilled through the baffle plate. 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 baffle plates
At Guanxin, we are committed to providing high-quality baffle plates that meet and exceed industry standards. We use state-of-the-art manufacturing processes and inspection techniques to ensure that our baffle plates are of the highest quality and can withstand the demands of industrial applications. Our baffle plates are made from a wide range of materials and are designed to meet the specific requirements of our customers’ applications.
Baffle Plates can be produced by forging, casting. We mainly produce baffle plates by forging, cutting and rolling processes. We will take you through the step-by-step process of manufacturing baffle plates, from the materials used to the final product.
Here is an example of low alloy steel steam generator baffle plate forgings recently produced by our company. The steam generator baffle 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 baffle plate forgings is as follows:
Step 1: Raw Material Selection and Preparation
The first step in the manufacturing process of baffle plates is selecting the appropriate raw materials. Baffle Plates 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 baffle plates. 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 baffle plate 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 Baffle Plates
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 Baffle Plates
After the forging of the baffle plate 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 baffle 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 Baffle Plates
After the forging and heat treatment process, the baffle plates 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 baffle plate 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 baffle 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 Baffle Plate
In this process, the baffle plate’s end face undergoes three stages: roughing, semi-finishing, and finishing. Roughing involves removing excess material to shape the baffle plate. This step is followed by semi-finishing, which further refines the baffle plate’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 baffle plates 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 baffle plate material and the application requirements. After the surface treatment, the baffle plates are cleaned and inspected.
The surface finish of baffle plates is critical in ensuring proper sealing and maintaining the integrity of the connection. The following guidelines should be observed:
- The baffle plate face must be free of defects, such as burrs, scratches, and pits.
- The surface finish of the baffle plate 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 baffle plates and 6.3 μm (250 μin) for flat face baffle plates.
Process 2: Drilling of the Baffle Plate
The drilling process involves creating precise holes in the baffle plate according to predetermined measurements and specifications. These holes will accommodate the tubes that will be fitted into the baffle plate. 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 baffle plate 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 Baffle Plate
In this sequence, the inner hole slot of the baffle plate 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 baffle plate. 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 Baffle Plate
The final process involves chamfering the baffle plate, which means creating a beveled edge at the intersection of the holes and the baffle plate’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 baffle plate. 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 Baffle Plate
Once the chamfering process is complete, it is crucial to remove any remaining burrs or sharp edges from the baffle plate. This process, known as deburring, helps ensure that the baffle plate 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 baffle plates 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 baffle plates’ mechanical properties and integrity. In addition, a visual inspection is performed to assess surface finish, cleanliness, and overall artistry.
Baffle 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 baffle 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 baffle 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 baffle 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 baffle 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 baffle plate forging, the use of special V-shaped vertebrae to ensure the deformation of the center of the baffle 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 baffle 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 baffle 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 baffle plates is essential to their manufacture and use. The marking aims to provide information about the baffle plate’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 ;
- Baffle Plate design model.
The standard also specifies the location of the marking on the baffle plate. Typically, the marking is placed on the raised face of the baffle plate near the bolt holes. In some cases, the marking may be located on the baffle plate hub or the plate itself.
Step 8: Packaging
Packaging is an important step in the manufacturing process of baffle plates. Proper packaging helps to protect the baffle plates from damage during transportation and storage.
The baffle plates 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 baffle plates to prevent any movement or shifting during transportation.
Step 9: Transportation
Transportation is the final step in the manufacturing process of baffle plates. The baffle plates 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 baffle plates are delivered on time and in good condition. The baffle plates are typically transported using trucks, ships, or planes, depending on the distance and location of the customer.
The manufacturing process of baffle plates is a complex process that requires precise techniques and high-quality materials to ensure optimal performance and durability. The Complete Guide to Manufacturing Baffle Plates provides a comprehensive resource for engineers, manufacturers, and technicians involved in the production of baffle plates.
In this book, we have covered every aspect of the baffle plate manufacturing process, from raw material selection and preparation to transportation. By following the guidelines provided in this book, you can ensure that your baffle plates are of the highest quality and meet industry standards.
Assembly and Integration Baffle Plate
Once the baffle plate 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 baffle plate and securing them using various methods, such as expansion, welding, or brazing. The baffle plate, 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 baffle plate is fabricated, inspected, and integrated into the heat exchanger or pressure vessel, contributing to the overall efficiency and reliability of the system.
What principles should be followed in the arrangement of the baffle plate?
In the shell and tube heat exchanger, the principles of the arrangement of the baffle plate are
The arrangement of the baffle plate must meet the requirements of the process design conditions. In particular, the form of the baffle plate, the spacing of the baffle plate, near the shell material import and export of the baffle plate position must meet the process design conditions as far as possible;
In the case of process design conditions without special requirements, the baffle plate should generally be laid out at equal intervals, the baffle plate at both ends of the tube bundle as close as possible to the shell process inlet and outlet receiver;
Horizontal heat exchanger shell process for single-phase clean fluid, the baffle plate gap should be arranged horizontally up and down; if the gas contains a small amount of liquid, then the gap should be opened in the lowest part of the baffle plate open liquid port; if the liquid contains a small amount of gas, then the gap should be opened in the highest part of the baffle plate down the vent;
Horizontal heat exchanger, condenser, and reboiler shell process medium for the coexistence of gas and liquid phase or liquid containing solid materials, the baffle plate gap should be arranged vertically around and open the liquid port at the lowest part of the baffle plate.
What is the minimum and maximum spacing for setting the baffle plate?
In the shell and tube heat exchanger, the minimum distance between the baffle plate is generally not less than one-fifth of the inner diameter of the cylinder and not less than 50 mm; in special cases, a smaller distance is also desirable. Small spacing will increase the flow rate; considering the heat transfer and the balance of pressure drops, the general baffle plate spacing should be at least 30% of the shell’s inner diameter. The maximum spacing can be equal to the inner diameter of the shell; if further increase makes the heat transfer efficiency decline, in addition to no support span too large will induce vibration.
Application of baffle plates
Baffle Plate is widely used in column tube heat exchanger, boiler, pressure vessel, turbine, large central air conditioning, and other industries.
This baffle plate is used in various industries:
Baffle Plates used in Oil and Gas Pipelines;
Baffle Plates used in Chemical Industry;
Baffle Plates used in Plumbing;
Baffle Plates used in Heating;
Baffle Plates used in Water Supply Systems;
Baffle Plates used in Power Plants;
Baffle Plates used in the Paper & Pulp Industry;
Baffle Plate uses in General Purpose Applications;
Baffle Plates used in Fabrication Industry;
Baffle Plate uses in Food Processing Industry;
Baffle Plates Use in Structural Pipe.
How to purchase the correct baffle plates?
- Flat face (FF): This type of baffle plate 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 baffle plate 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 baffle plate face has a specially designed groove to accommodate a metallic ring gasket. The groove is cut into the surface of the baffle plate, and the gasket sits in the groove to create a tight seal. This type of baffle plate face is typically used in high-pressure applications.
Once you have identified the material and baffle plate type, the next step is to determine the size and pressure class of the baffle plate. baffle plates are available in various sizes and pressure ratings, and it’s crucial to select the correct size and pressure class to ensure that the baffle plate can withstand the intended operating conditions. You should consult the system specifications and design to determine the appropriate size and pressure class.
The baffle plate face’s surface finish directly impacts the seal’s quality between the baffle plates. 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 baffle plates.
How to select baffle plates manufacturer?
Choosing the right baffle plates 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 baffle plate needs.
Why Choose Guanxin to Be Your Baffle Plate Supplier?
Guanxin is a well-established and reputable manufacturer and supplier of baffle plates 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 baffle plate supplier:
- High-quality products: Guanxin is committed to providing high-quality baffle plates 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 baffle plates at an affordable price.
- Wide range of products: Guanxin offers a wide range of baffle plates, 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 Baffle Plates
|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 baffle plates
Tube and baffle 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 baffle 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 baffle 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 baffle plate thickness minus 3mm, when the thickness of the baffle 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 baffle 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 baffle plate using not full expansion type, when the thickness of the baffle plate is greater than 50mm, the expansion depth is still 50mm.
The baffle 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 baffle 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 baffle plate, generally using a welded structure, regardless of its pressure and temperature. In order to avoid fluid stagnation on the baffle 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 baffle 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 baffle plate, the structure is generally used for stainless steel and baffle 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 baffle 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 baffle 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 baffle plate distance to be considered larger, about 16mm, in the range of 10-12mm from the surface of the baffle 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 baffle 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 baffle plate after processing and heat exchanger tube to form a butt weld form, to have special equipment, the welding gun from the baffle 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 baffle 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 baffle 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 baffle 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.