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904L alloy steel has the following characteristics: 904L is a highly alloyed austenitic stainless steel with low carbon content. This steel is designed for environments with harsh corrosion conditions. Initially, this alloy was developed for corrosion resistance in dilute sulfuric acid. This feature has been proven to be very successful through years of practical application. 904L has been standardized in many countries and has been approved for use in the manufacture of pressure vessels. 904L alloy, like other commonly used CrNi austenitic steels, has good resistance to pitting and crevice corrosion, high resistance to stress corrosion cracking, good resistance to intergranular corrosion, good processability, and weldability. The maximum heating temperature during hot forging can reach 1180 degrees Celsius, and the minimum stop forging temperature is not less than 900 degrees Celsius. This steel can be hot formed at 1000-1150 degrees Celsius. The heat treatment process of this steel is 1100-1150 degrees Celsius, and it is rapidly cooled after heating. Although this steel can be welded using universal welding processes, the most appropriate welding methods are manual arc welding and tungsten inert gas arc welding. When using manual arc welding to weld plates with a diameter not exceeding 6mm, the diameter of the welding rod shall not exceed 2.5mm; When the plate thickness is greater than 6 millimeters, the diameter of the welding rod is less than 3.2 millimeters. When heat treatment is required after welding, it can be done by heating at 1075-1125 degrees Celsius and then rapidly cooling. When using tungsten inert gas arc welding, the filler metal can be used with the same welding rod. After welding, the weld seam must be pickled and passivated.     904L metallographic structure 904L is a completely austenitic structure, and compared to austenitic stainless steels with high molybdenum content, 904L is not sensitive to the precipitation of ferrite and alpha phase.     Corrosion resistance of 904L Due to the low carbon content of 904L (maximum 0.020%), there will be no carbide precipitation under general heat treatment and welding conditions. This eliminates the risk of intergranular corrosion that occurs after general heat treatment and welding. Due to its high chromium nickel molybdenum content and the addition of copper, 904L can be passivated even in reducing environments such as sulfuric acid and formic acid. The high nickel content results in a lower corrosion rate even in the active state. In pure sulfuric acid with a concentration range of 0-98%, the usage temperature of 904L can reach up to 40 degrees Celsius. In pure phosphoric acid with a concentration range of 0-85%, its corrosion resistance is very good. Impurities have a strong impact on the corrosion resistance of industrial phosphoric acid produced by wet process technology. Among all types of phosphoric acid, 904L has better corrosion resistance than ordinary stainless steel. In highly oxidizing nitric acid, 904L has lower corrosion resistance compared to high alloyed steel grades without molybdenum. In hydrochloric acid, the use of 904L is limited to lower concentrations of 1-2%. Within this concentration range. The corrosion resistance of 904L is better than that of conventional stainless steel. 904L steel has high resistance to pitting corrosion. Its resistance to crevice corrosion is also very good in chloride solutions. The high nickel content of 904L reduces the corrosion rate in pits and crevices. Ordinary austenitic stainless steel may be sensitive to stress corrosion in an environment rich in chloride at temperatures above 60 degrees Celsius. By increasing the nickel content of the stainless steel, this sensitization can be reduced. Due to its high nickel content, 904L exhibits high resistance to stress corrosion cracking in chloride solutions, concentrated hydroxide solutions, and environments rich in hydrogen sulfide.     904L Tube sheet  A 904L tube sheet is a component used in various industrial applications particularly in heat exchangers and condensers. The 904L stainless steel tube sheet is specifically chosen for its superior resistance to aggressive environments, such as those containing sulfuric acid, phosphoric acid, and chloride solutions. It offers exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking, making it highly suitable for applications in the chemical, petrochemical, and offshore industries. The use of 904L stainless steel tube sheets ensures the long-term reliability and performance of heat transfer equipment. Its corrosion resistance properties allow for extended service life and reduced maintenance requirements, resulting in cost savings and enhanced operational efficiency. Choose 904L tube sheets for superior corrosion resistance and reliable performance in demanding environments. Experience the benefits of this high-quality stainless steel alloy for your heat exchangers and condensers.     904L flange 904L flanges are commonly used in industries such as chemical processing, petrochemical, pharmaceutical, and offshore applications. Their resistance to corrosion makes them suitable for handling corrosive fluids and gases. Additionally, 904L flanges offer excellent strength, durability, and weldability, making them a reliable choice for critical applications. The use of 904L flanges can help ensure the integrity and longevity of piping systems by providing a robust and corrosion-resistant connection. They are available in various types, including slip-on, weld neck, blind, and threaded flanges, to suit different installation requirements. In summary, 904L flanges are specifically made from 904L stainless steel, which offers superior corrosion resistance in demanding environments. Their use can enhance the reliability and performance of piping systems, making them ideal for applications where corrosion resistance is paramount.   904L application areas: 904L alloy is a versatile material that can be applied in many industrial fields: 1. Petroleum and petrochemical equipment, such as reactors in petrochemical equipment. 2. Storage and transportation equipment for sulfuric acid, such as heat exchangers. 3. The flue gas desulfurization device in power plants is mainly used in the tower body, flue, door panels, internal components, spray systems, etc. of the absorption tower. 4. Scrubbers and fans in organic acid treatment systems.     Similar grades GB/T UNS AISI/ASTM ID W.Nr 00Cr20Ni25Mo4.5Cu N08904 904L F904L 1.4539     904L chemical composition C Si Mn P S Cr Ni Mo Cu Fe 0.02 1 2 0.045 0.035 19-23 23-28 4-5 1-2       Mechanical properties Tensile strength Yield Strength Elongation Density Melting point RmN/mm Rp0.2N/mm A5％ 8.0g/cm3 1300-1390℃       Wuxi Changrun has provided high-quality tube sheets, nozzles, flanges, and customized forgings for heat exchangers, boilers, pressure vessels, etc. to many well-known petrochemical enterprises at home and abroad. Our customers include PetroChina, Sinopec, Chevron, Bayer, Shell, BASF, etc. Send your drawings to sales@wuxichangrun.com We will provide you with the best quotation and the highest quality products.  

Structural design The structural design of low-temperature pressure vessels should consider sufficient flexibility, and the main requirements are as follows: ① The structure should be as simple as possible to reduce the constraints between welded components; ② Structural design should avoid generating excessive temperature gradients; ③ Sharp changes in the cross-section should be avoided as much as possible to reduce local stress concentration. The inner end of the plug-in nozzle should be polished into a rounded corner to ensure a smooth transition; ④ The connection welds of attachments should not be discontinuous or spot welded; ⑤ The saddle, manifold lug, support leg (excluding spherical tanks) or skirt of the container should be equipped with a pad or connecting plate to avoid direct welding with the container shell. The pad or connecting plate should be considered based on low-temperature materials; ⑥ The reinforcement of takeover should be carried out as much as possible using integral reinforcement or thick walled pipe reinforcement. If reinforcement pads are used, the weld seam should have a smooth transition; ⑦ For containers that cannot undergo overall heat treatment, if the welded components need to be stress relieved, consideration should be given to the individual heat treatment of the components.       Opening for connecting pipes The opening of the connecting pipe for low-temperature pressure vessels should be avoided as much as possible from the main weld seam and its surrounding area. If it is necessary to open a hole in the weld seam area, it should comply with the requirements of relevant standards. The connecting pipes on low-temperature pressure vessels should meet the following requirements: ① The wall thickness of the section welded to the shell should not be less than 5mm. For pipes with a diameter of DN ≤ 50mm, thick walled pipes should be used, and the extended part should be made of ordinary seamless steel pipes with a wall thickness; ② Bends made by simmering or pressing should be used at bends, and straight pipe welding (shrimp elbows) should not be used; ③ For plug-in nozzles, the sharp corners of the inner pipe end of the shell wall need to be turned or polished to a rounded corner of R ≥ 3mm; ④ The longitudinal weld seam and the circumferential weld seam between pipe sections when using coiled pipes for takeover should adopt a fully welded structure; ⑤ For hazardous media that are extremely flammable or highly toxic, or when the pressure is ≥ 1.6 MPa, The T-shaped joint should adopt a seamless extruded tee or a structure with thickened pipe openings and welding.     Flange Butt welded flanges should be used for flanges that meet the following conditions: ① Container flanges with a design pressure of ≥ 1.60MPa and containing highly flammable or toxic media, or connecting flanges with significant external loads; ② Vessel flanges and connecting flanges with a design pressure of ≥ 2.50MPa. Butt welded flanges should be produced using seamless forging or rolling processes, and it is not allowed to use thick steel plates for cutting; It is allowed to use structural steel or steel plates bent or welded, but post weld heat treatment is required. If steel plate bending is used, the steel plate should be cut into strips along the rolling direction. When bending, the surface of the steel plate should be parallel to the centerline of the flange, and ultrasonic testing must also be performed on the steel plate.     Fasteners The main requirements are as follows: ①The bolts, stud, and other fasteners used for flanges of low-temperature pressure vessels shall not use general ferrite commodity fasteners matched with nuts. General commodity nuts are allowed to be used, but the operating temperature should not be lower than -40 ℃; ② Recommend using elastic bolts and studs with a core diameter not exceeding 0.9 times the thread root diameter and no thread in the middle; ③ For ferritic steel vessels with a design temperature not lower than -100 ℃, ferritic steel fasteners (studs, bolts, nuts, washers) should be used. For austenitic steel vessels with a design temperature lower than -100 ℃, austenitic steel fasteners should be used; ④ A2 grade austenitic steel commercial fasteners in accordance with GB 3098.6 "Mechanical Properties of Fasteners - Stainless Steel Bolts, Screws, and Studs" can be used in low-temperature pressure vessels not lower than -196 ℃; ⑤ For stress reducing conditions, when the adjusted impact test temperature is equal to or higher than -20 ℃, general ferrite commodity fasteners can be used.     Sealing gasket The commonly used sealing gaskets for low-temperature pressure vessels include gaskets made of metal materials (including semi metal gaskets) and non-metallic materials. The conditions and requirements are as follows. ① Metal materials used for sealing gaskets with temperatures below -40 ℃ should be austenitic stainless steel, copper, aluminum, and other metal materials that have no obvious transformation characteristics at low temperatures, including the metal strip of spiral wound gaskets, the shell of metal wrapped gaskets, and hollow or solid metal gaskets. ② Non metallic sealing gaskets should be made of materials that exhibit good elasticity at low temperatures, such as asbestos, flexible (expanded) graphite, polytetrafluoroethylene, etc. The usage conditions are as follows: The flange sealing gasket with a temperature not lower than -40 ℃ and a pressure not higher than 2.5MPa is allowed to use high-quality asbestos rubber sheets, asbestos free rubber sheets, flexible (expanded) graphite sheets, polyethylene sheets, etc; High quality asbestos rubber sheets soaked in paraffin are allowed for flange gaskets with a temperature not lower than -120 ℃ and a pressure not higher than 1.6MPa.     Welding The main requirements are as follows. ① For A B. All C-class welds should adopt a fully penetrated structure. For Class D welds, except for the welding between the flange and the container wall, the welding between small diameter nozzles (DN ≤ 50mm) and thicker heads or cover plates, and the connection between pipe joints with internal threads and the container wall, which can be in accordance with the relevant provisions of HG 20582, full penetration structures should also be used. ② Before welding low-temperature pressure vessels, welding process evaluation should be carried out, with a focus on the low-temperature Charpy (V-notch) impact test of the weld seam and heat affected zone. The qualification index should be determined according to the requirements of the base material and should not be lower than the performance of the base material. ③ During the welding process, the welding wire energy should be strictly controlled within the range specified in the process evaluation. It is advisable to choose a smaller welding wire energy for multi pass welding. ④ The butt weld must be fully welded, and the excess height of the weld should be minimized as much as possible, not exceeding 10% of the thickness of the welded part, and not exceeding 3mm. The fillet weld should be smooth and not allowed to protrude outward. The surface of the weld seam should not have defects such as cracks, pores, and undercuts, and there should be no sharp shape changes. All transitions should be smooth. ⑤ Arc ignition is not allowed in non welding areas. Arc ignition should be carried out using arc plates or within the groove. ⑥ Welding attachments, fixtures, braces, etc. must use the same welding materials and welding processes as the shell material, and be welded by qualified formal welders. The length of the weld bead must not be less than 50mm. ⑦ Surface damage to containers caused by mechanical processing, welding, or assembly, such as scratches, welding scars, arc pits, and other defects, should be repaired and ground. The wall thickness after grinding shall not be less than the calculated thickness of the container plus corrosion allowance, and the grinding depth shall not exceed 5% of the nominal thickness of the container and shall not exceed 2mm. ⑧ Discontinuous or spot welded joints are not allowed.     Wuxi Changrun has provided high-quality tube sheets, nozzles, flanges, and customized forgings for heat exchangers, boilers, pressure vessels, etc. to many well-known petrochemical enterprises at home and abroad. Our customers include PetroChina, Sinopec, Chevron, Bayer, Shell, BASF, etc. Send your drawings to sales@wuxichangrun.com We will provide you with the best quotation and the highest quality products.

1. Theoretical basis for tube sheet calculation   The structure of shell and tube heat exchangers is complex, and there are many factors that affect the strength of the tube sheet. In particular, the tube sheet of fixed tube sheet heat exchangers is subjected to the most complex force. The design specifications of various countries basically consider the tube sheet as a circular flat plate that bears uniformly distributed loads, is placed on an elastic foundation, and is uniformly weakened by the tube holes (Figure 1).   Due to the many factors that affect the strength of the tube sheet, it is difficult and complex to accurately analyze the strength of the tube sheet. Therefore, various countries simplify and assume the formula for calculating the thickness of the tube sheet to obtain an approximate formula.   The loads that cause stress on the tube sheet include pressure (tube side pressure Pt, shell side pressure Ps), thermal expansion difference between the tube and shell, and flange torque. The mechanical model of the calculation method for the tube sheet of the heat exchanger is shown in Figure 2.   1.1 The design specifications of various countries consider the following factors to varying degrees for the tube sheets: 1) Simplifying the actual tube sheet into a homogeneous equivalent circular flat plate based on equivalent elasticity weakened by regular arrangement of tube holes and reinforced by tubes has been adopted by most countries' tube plate specifications today. 2) The narrow non piping area around the tube sheet is simplified as a circular solid plate based on its area. 3) The edge of the tube sheet can have various types of connection structures, which may include shell side cylinders, channel cylinders, flanges, bolts, gaskets, and other components. Calculate according to the actual elastic constraint conditions of each component on the edge of the tube sheet. 4) Consider the effect of flange torque on the tube sheet. 5) Consider the temperature difference stress caused by the thermal expansion difference between the heat exchange tube and the shell side cylinder, as well as the temperature stress caused by the temperature difference at various points on the tube sheet. 6)Calculate various equivalent elastic constants and strength parameters converted from porous plates with heat exchange tubes to equivalent solid plates.     1.2 Theoretical basis for GB151 tube sheet calculation The mechanical model considers the tube plate as an axial symmetry structure and assumes that the tubesheets at both ends of the heat exchanger have the same material and thickness. For fixed tube sheet heat exchangers, the two tube sheets should also have the same boundary support conditions.   1) The supporting effect of tube bundle on tube sheet Consider the tube sheet as an equivalent circular flat plate uniformly weakened and placed on an elastic foundation. This is because in the structure of shell and tube heat exchangers, the diameter of the majority of tubes is relatively small compared to the diameter of the tube sheet, and the number of tubes is sufficient. It is assumed that they are uniformly distributed on the tube sheet, so the support effect of each discrete heat exchange tube on the tube sheet can be considered uniform and continuous, and the load borne by the tube sheet is also considered uniformly distributed.   The tube bundle has a restraining effect on the deflection and rotation angle of the tube sheet under external loads. The restraining effect of the tube bundle can reduce the deflection of the tube sheet and lower the stress in the tube sheet. The tube bundle has a restraining effect on the angle of the tube sheet. Through analysis and calculation of actual parameters, it was found that the restraining effect of the tube bundle on the angle of the tube sheet has a very small impact on the strength of the tube sheet and can be completely ignored. Therefore, this   The specification does not consider the constraint effect of tube bundles on the corner of the tube sheet, but only considers the constraint effect of tube bundles on the deflection of the tube sheet. For fixed tube sheet heat exchangers, the tube reinforcement coefficient K is used to represent the tube sheet.   The bending stiffness of the perforated tube plate is η D The elastic foundation coefficient N of the tube bundle represents the pressure load required to be applied on the surface of the tube plate to cause unit length deformation (elongation or shortening) of the tube bundle in the axial direction.   the pipe reinforcement coefficient K and substitute it into the expressions D and N, so that ν P=0.3: This coefficient indicates the strength of the elastic foundation relative to the tube plate's inherent bending stiffness, reflecting the enhanced load-bearing capacity of the tube bundle on the plate. It is a crucial parameter that characterizes the strengthening effect of the tube bundle on the plate. If the elastic foundation of the plate is weak, the enhancing effect of the heat exchange tubes is minimal, resulting in a small K value. Consequently, the plate's deflection and bending moment distribution resemble those of ordinary circular plates lacking an elastic foundation. Specifically, when K equals zero, the plate becomes an ordinary circular plate. Based on the theory of elastic foundation circular plates, the plate's deflection is not solely determined by the tube's strengthening coefficient K, but also by its peripheral support and additional loads, quantitatively represented by the total bending moment coefficient m.   When the periphery of the tube sheet is simply supported, MR=0, then m=0; When the periphery of the tube sheet is fixed, the corner of the edge of the tube sheet φ R=0, from which a specific value of m can be obtained (the expression is omitted); When the periphery of the tube plate only bears the action of bending moment, i.e. VR=0, then m=∞. Under certain boundary support conditions, as the K value gradually increases, the deflection and bending moment of the tubesheet exhibit a attenuation and wavy distribution from the periphery to the center. The larger the K value, the faster the attenuation and the more wave numbers. During the process of increasing K value, when passing through a certain boundary K value, new waves will appear in the distribution curve. At the center of the plate, the curve changes from concave (or concave) to concave (or concave). Solving the derivative equation of the distribution curve can obtain the K boundary value of the curve with an increase in wave number.   Taking the simple support around the tube sheet as an example, as the strengthening coefficient K of the tube increases, the radial bending moment distribution curve and the boundary K value when new waves appear are shown in Figure 31. At the same time, it can be seen that the radial extreme value also moves away from the center of the tube sheet towards the periphery as the K value increases.   For the elastic foundation plate with peripheral fixed support, the radial bending moment distribution shows a similar trend with the change of K value, as shown in Figure 3. The difference from a simply supported boundary is that the maximum radial bending moment of the elastic foundation plate supported by a fixed boundary is always located around the circular plate, while the extreme point of the second radial bending moment moves away from the center of the plate and towards the periphery as K increases.   For floating head and filled box heat exchanger tube sheets, the modulus K of the tube bundle is similar to the elastic foundation coefficient N of the fixed tube sheet, which also reflects the strengthening effect of the tube bundle as an elastic foundation on the tube sheet.   2) The weakening effect of tube holes on tube sheets The tube sheet is densely covered with dispersed tube holes, so the tube holes have a weakening effect on the tube sheet. The weakening effect of tube holes on the tube sheet has two aspects:   The overall weakening effect on the tube sheet reduces both the stiffness and strength of the tube sheet, and there is local stress concentration at the edge of the tube hole, only considering peak stress.   This specification only considers the weakening effect of openings on the overall tube sheet, calculates the average equivalent stress as the basic design stress, that is, approximately considers the tube sheet as a uniformly and continuously weakened equivalent circular flat plate. For local stress concentration at the edge of the tube hole, only peak stress is considered. But it should be considered in fatigue design.   The tube hole has a weakening effect on the tube sheet, but also considers the strengthening effect of the pipe wall, so the stiffness weakening coefficient is used η And strength weakening coefficient μ。 According to elastic theory analysis and experiments, this specification stipulates η and μ＝ 0.4.   3) Equivalent diameter of tube sheet layout area The calculation of the reinforcement coefficient for fixed tube sheets assumes that all pipes are uniformly distributed within the diameter range of the cylinder. In fact, under normal circumstances, there is a narrow non pipe area around the tube sheet, which reduces the stress at the edge of the tube sheet.   The tube layout area is generally an irregular polygon, and now the equivalent circular pipe layout area is used instead of the polygonal pipe layout area. The value of the equivalent diameter Dt should make the supporting area of the tube on the tube sheet equal. The diameter size directly affects the stress magnitude and distribution of the tube plate. In the stress calculation of the fixed tube sheet in GB151, the stress located at the junction of the annular plate and the pipe layout area is approximately taken as the stress of the full pipe layout tube plate at a radius of Dt/2. Therefore, the standard limits this calculation method to only be applicable to situations where the non pipe layout area around the tube plate is narrow, that is, when the non dimensional width k of the non pipe layout area around the tube sheet is small, k=K (1)- ρ t) ≤ 1.   Whether it is a fixed tube sheet heat exchanger, or a floating head or filled box heat exchanger, when calculating the area of the tube layout area, it is assumed that the tubes are uniformly covered within the range of the tube layout area.   Assuming there are n heat exchange tubes with a spacing of S. For a triangular arrangement of tube holes, the supporting effect of each tube on the tube sheet is the hexagonal area centered on the center of the tube hole and with S as its inner tangent diameter, i.e;   For tubes with square arrangement of tube holes, the supporting area of each tube on the tube sheet is a square area centered on the center of the tube hole and with S as the side length, i.e. S2.   The tube sheet layout area is the area enclosed by connecting the supporting area of the outermost tube of the tube sheet, including the supporting area of the outermost tube itself.   For a single pass heat exchanger tube sheet with uniformly distributed heat exchange tubes, the supporting area of all n heat exchange tubes on the tube sheet is the area of the tube layout area.   4) Consider the bending effect of the tube sheet, as well as the tensile effect of the tube sheet and flange along their central plane.   5) Assuming that when the flange deforms, the shape of its cross-section remains unchanged, but only the rotation and radial displacement of the center of gravity around the ring section. Due to this rotation and radial displacement, the radial displacement at the connection point between the flange and the center surface of the tube sheet should be coordinated and consistent with the radial displacement along the center surface of the tube sheet itself.   6) Due to temperature expansion difference γ The axial displacement of the shell wall caused by the shell side pressure ps and the tube side pressure pt should be coordinated and consistent with the axial displacement of the tube bundle and tube sheet system around the tube sheet.   7) The corner of the tube sheet edge is constrained by the shell, flange, channel, bolt, and gasket system, and its corner should be coordinated and consistent at the connection part.   8) When the tube sheet is also used as a flange, the influence of flange torque on the stress of the tube sheet is considered. In order to ensure sealing, it is stipulated that the flange stress needs to be checked for the extended part of the tube sheet that also serves as a flange. At this time, when calculating the flange torque, it is considered that the tube sheet and flange jointly bear the external force moment, so the ground force moment borne by the flange will be reduced.     About us Wuxi Changrun has provided high-quality tube sheets, nozzles, flanges, and customized forgings for heat exchangers, boilers, pressure vessels, etc. to many well-known petrochemical enterprises at home and abroad. Our customers include PetroChina, Sinopec, Chevron, Bayer, Shell, BASF, etc. Send your drawings to sales@wuxichangrun.com We will provide you with the best quotation and the highest quality products.  

Reinforcement structure Pressure vessel connection reinforcement usually adopts three reinforcement structures: reinforcement pad, thick walled pipe reinforcement, and integral forging reinforcement, as shown in the following figure.   Reinforcement pad As shown in the above figure (a), the reinforcing pad is welded to the connection between the shell and the connecting pipe, with a simple structure and convenient manufacturing. However, the reinforcing pad cannot fully adhere to the metal of the shell, resulting in poor heat transfer effect. When used above medium temperature, there is a significant thermal expansion difference between the two, which causes significant thermal stress in the local area of the reinforcing pad; In addition, the reinforcing pad is connected to the shell by overlapping, which makes it difficult to form a complete structure with the shell, resulting in poor fatigue resistance. Generally used in normal temperature, static load, medium and low pressure situations. Generally, an M10 threaded hole is required on the reinforcing pad for the passage of compressed air to check the tightness of the weld seam.     Thick walled pipe reinforcement Weld a thick walled connecting pipe at the opening, as shown in (b) above. Due to the thickened part of the takeover being within the maximum stress zone, it is more effective in reducing the stress concentration factor than the reinforcing pad. The structure is simple, there are few welds, and the welding quality is easy to inspect, so the reinforcement effect is good. High strength low alloy steel pressure vessels generally adopt this structure due to their high sensitivity to material notches, but it is necessary to ensure full penetration of the weld seam.     Reinforcement of integral forgings As shown in the above figure (c), the connecting pipe and part of the shell, along with the reinforcement part, are made into a complete forging, and then welded with the shell and connecting pipe. The reinforcement metal is concentrated in the area with the highest stress in the opening, which can effectively reduce the stress concentration coefficient; Butt welds can be used, and the weld and its heat affected zone can be moved away from the maximum stress point, with good fatigue resistance. But the supply of forgings is difficult, and the manufacturing cost is high. So it is only applied in important pressure vessels.   Wuxi Changrun manufactures various Nozzles for integral reinforcement, include Q-Lip Nozzles, integrally reinforced nozzles, self reinforced nozzles, flat barrel nozzles, contoured barrel nozzles, stub end nozzles and customized nozzles. Materials include Carbon Steel & Alloy Steel, Stainless Steel & Duplex Steel, Nickel & Nickel Alloys, Titanium & Titanium Alloys. Send your drawings to sales@wuxichangrun.com We will provide you with the best quotation and the highest quality products.

Forging ratio is an indicator used to indicate the degree of metal deformation during the forging process, usually defined as the ratio of the cross-sectional area of the metal before and after forging.   The calculation method for forging ratio can be the elongation forging ratio or the upsetting forging ratio. The elongation forging ratio refers to the ratio of the cross-sectional area of the steel ingot or billet before elongation to the cross-sectional area after elongation. The upsetting forging ratio, also known as the upsetting ratio or compression ratio, refers to the ratio of the cross-sectional area of the steel ingot or billet after upsetting to the cross-sectional area before upsetting. The selection of forging ratio is crucial for ensuring the quality and performance of forgings, and factors such as different metal materials, forging performance requirements, process types, and the shape and size of forgings need to be considered. For example, alloy structural steel ingots typically require a larger forging ratio, while electroslag steel ingots have better quality and require a smaller forging ratio.   The size of the forging ratio directly affects the mechanical properties and forging quality of the metal. Increasing the forging ratio is beneficial for improving the structure and properties of the metal, but excessive forging ratios may also lead to unnecessary waste and increased workload. Therefore, while ensuring the quality of forgings, it is advisable to choose a smaller forging ratio as much as possible.     1. Basic definition of forging ratio The ratio of the cross-sectional area of a metal billet before and after forging is called the forging ratio. It represents the magnitude of forging deformation, and the forging ratio can be calculated using the following formula:     2. Calculation methods of forging ratio Note: (1) The forging ratio of chamfered steel ingots is not included in the total forging ratio; (2) When continuously elongating or upsetting, the total forging ratio is equal to the product of the sub forging ratios; (3) When there is elongation between two upsets and when there is elongation between two upsets, the total forging ratio is equal to the sum of the two sub forging ratios, and it is required that each sub forging ratio is not less than 2.     About us: Wuxi Changrun has provided high-quality tube sheets, nozzles, flanges, and customized forgings for heat exchangers, boilers, pressure vessels, etc. to many well-known petrochemical enterprises at home and abroad. Our customers include PetroChina, Sinopec, Chevron, Bayer, Shell, BASF, etc. Send your drawings to sales@wuxichangrun.com We will provide you with the best quotation and the highest quality products.     Our company has 27 international and domestic first-class brand drilling equipment that have been put into use, including 11 deep hole drills. We have advantages such as large processing specifications (maximum diameter of 8.6m), batch production, mature process plans, and standardized quality control. The processed tube sheet products are widely used in industries such as seawater desalination, heat exchangers, pressure vessels, paper machines, petroleum refining, steam turbines, and nuclear power.  

Shell and tube heat exchangers account for approximately 90% of the total amount of heat exchangers used in industry, making them the most widely used type of heat exchanger.   The typical structural forms of shell and tube heat exchangers include fixed tube sheet heat exchangers, U tube heat exchangers, floating head heat exchangers, stuffing box heat exchanger, kettle reboilers, double tube sheet heat exchangers, brace tube sheet heat exchangers, flexible tube sheet heat exchangers, and Spiral Wounded Heat Exchangers.   1. Fixed tube sheet heat exchanger The fixed tube sheet heat exchanger (Figure 1) is a fixed connection (integral or clamped) between the two end tube sheets and the shell. This is the most widely used type of heat exchanger. The two ends of the heat exchange tube are fixed on the tube sheet, which is welded to the shell.   Fixed tube sheet heat exchangers are suitable for various occasions: 1)In situations where the temperature difference between the metal on the tube and shell side is not very large and the pressure is high. When the temperature difference between the metal on the tube and shell side is large, the pressure cannot be too high because the large temperature difference will inevitably increase the expansion joint, which has poor pressure resistance. 2) Due to the inability of the shell side to be mechanically cleaned, it is required that the shell side medium be clean; Or in situations where scaling may occur but can be removed through chemical cleaning.   Advantages: 1) It has a simple structure, less use of forgings, and low manufacturing cost. 2) The tube side can be divided into various forms of multiple passes, and the shell side can also be divided into two passes. 3) The heat transfer area is 20% to 30% larger than that of a floating head heat exchanger. 4) The bypass leakage is relatively small.   Disadvantages: 1) Not suitable for situations where there is a significant difference in thermal expansion deformation between heat exchange tubes and shell side cylinders, as temperature difference stress can easily occur between the tube sheet and tube end, leading to damage. 2) After the corrosion of the pipe, it leads to the scrapping of the shell, and the lifespan of the shell components is determined by the lifespan of the pipe, so the equipment lifespan is relatively low. 3) The shell cannot be cleaned and inspection is difficult.     2. U-shaped tube heat exchanger The U-shaped tube heat exchanger (Figure 2) is a heat exchange tube with two ends fixed on the same tube plate, which is fixedly connected to the shell (integral or clamped).   U-shaped tube heat exchangers can be used in the following situations 1) The flow in the pipeline is clean fluid. 2) The pressure in the pipeline is particularly high. 3) In situations where there is a large temperature difference between the metal on the tube and shell sides, and fixed tube plate heat exchangers cannot even meet the requirements with expansion joints.   Advantages: 1) The free floating at the end of the U-shaped heat exchange tube solves the temperature difference stress and can be used for two media with large temperature differences. The temperature difference between the metal on the tube and shell side is not limited. 2) The tube bundle can be pulled out to facilitate frequent cleaning of the outer wall of the heat exchange tube. 3) With only one tube plate and a small number of flanges, the structure is simple and there are few leakage points, resulting in a lower cost. 4) It can work under high temperature and high pressure, and is generally suitable for t ≤ 500 ℃ and p ≤ 10MPa. 5) Can be used in situations where shell side scaling is relatively severe.   Disadvantages: 1) When the flow rate in the pipe is too high, it will cause serious erosion on the U-shaped bend section, affecting its service life. Especially for pipes with low R, the flow rate inside the pipe should be controlled. 2) The pipeline is not suitable for situations with heavy scaling. 3) Due to the limitation of u-tube Rmim and wide separation distance, the number of tubes in the fixed tube sheet heat exchanger is slightly less. 4) When the heat exchange tube leaks, except for the outer U-shaped tube, it cannot be replaced and can only be blocked. 5) The central part of the tube bundle has large pores, and the fluid is prone to short circuits, which affects the heat transfer effect. Therefore, partitions should be added to reduce short circuits. 6) Due to the large dead zone, it is only suitable for the inner guide tube. 7) The number of heat exchange tubes arranged on the tube plate is relatively small. 8) The U-shaped bending section of the outermost pipe, due to its large unsupported span, should cause fluid induced vibration problems. 9) When there are requirements for stress corrosion, careful consideration should be given.     3. Floating head heat exchanger The floating head heat exchanger (Figure 3) is a clamped type where one end of the tube sheet is fixedly connected to the shell, while the other end of the floating head tube sheet (including the floating head cover, backing device, etc.) floats freely inside the tube box. Therefore, there is no need to consider temperature difference stress, as there is a large temperature difference between the metal walls of the tube and shell sides.   Advantages: 1) The tube bundle can be pulled out for easy cleaning of the tube and shell side. 2) The shell wall and tube wall are not limited by temperature difference. 3) It can work under high temperature and high pressure, generally t ≤ 450 ℃ and p ≤ 6.4MPa. 4) Can be used in situations with severe scaling. 5) Can be used in pipeline corrosion scenarios.    Disadvantages: 1) It is difficult to take measures when leakage occurs during the operation of the floating head sealing surface inside the shell side medium. 2) Complex structure, high metal material consumption, and high cost. 3) The floating head structure is complex and affects the number of pipes arranged. 4) The pressure test fixture used during pressure testing is complex. 5) Metal materials consume a large amount and have a 20% higher cost.     stuffing box heat exchanger One end of the tube sheet is fixedly connected to the shell (clamp type), while the other end of the tube sheet floats freely inside the packing box.   The tube bundle can be extended and can be used for two media with a large temperature difference. The structure is also simpler than that of a floating head, making it easier to manufacture and more cost-effective than a floating head heat exchanger. Because the tube bundle can be pulled out, it is easy to maintain and clean. Suitable for use in media with severe corrosion.   4.1 Outside packed heat exchanger (Figure 4) Suitable for equipment with a diameter below DN700mm, and the operating pressure and temperature should not be too high. It is generally used in situations where p ≤ 2.0MPa.   4.2 Sliding tube sheet packing box heat exchanger At the sealing point on the inner side of the packing, there will still be a flow phenomenon etween the medium on the tube and shell side, which is not suitable for situations where the medium on the tube and shell side is not allowed to mix.   4.2.1 Single stuffing box heat exchanger (Figure 5) At the sealing point on the inner side of the packing, there will still be a flow phenomenon between the medium on the tube and shell side, which is not suitable for situations where the medium on the tube and shell side is not allowed to mix.   4.2.2 Double stuffing box heat exchanger (Figure 6) The structure is mainly sealed with the inner ring to prevent internal and external leakage, while the outer ring is used as an auxiliary seal to prevent external leakage. A leakage outlet pipe is set between the inner and outer sealing rings to connect with the low-pressure vent main. This structure can be used for medium with moderate harm, explosive and other media.     5. Kettle reboiler  The kettle reboiler (Figure 7) is a fixed connection (clamp type) between one end of the tube sheet and the shell, and the other end is a U-shaped or floating head tube bundle. The shell side is a single (or double) inclined cone shell with evaporation space, so the temperature and pressure on the tube side are higher than those on the shell side. Generally, the shell side medium is heated by the tube side medium. P ≤ 6.4 MPa. Advantages: 1) Suitable for bottom reboilers and side line siphon reboilers. 2) Save over 25% of equipment weight. 3) Good corrosion resistance. 4) It has a self-cleaning effect. In situations where there is a large temperature difference between the tube and shell side. 5) The total heat transfer coefficient has increased by more than 40%. 6) In situations with high vaporization rates (30-80%). 7) In situations where the liquid phase of the reboiled process medium is used as a product or requires high separation requirements. 8) Good corrosion resistance.   Disadvantages: 1) On heavy oil equipment, such as residual oil and crude oil equipment, there is no application history. 2) Not suitable for environments with wet hydrogen sulfide.     6.Double tube sheet heat exchanger The double tube sheet heat exchanger (Figure 8) has two tube sheets on each side, and one end of the heat exchange tube is connected to both tube sheets simultaneously. Mainly used for mixing the medium between the tube side and shell side, which will result in serious consequences. But manufacturing is difficult; High design requirements.   1) Corrosion prevention: Mixing the two media of the tube side and shell side can cause severe corrosion. 2) Labor protection: One route is a highly toxic medium, and infiltration into the other route can cause extensive system pollution. 3) In terms of safety, mixing the medium on the tube side and shell side can cause combustion or explosion. 4) Equipment contamination: Mixing of tube side and shell side media can cause polymerization or the formation of resin like substances. 5) Catalyst poisoning: The addition of another medium can cause changes in catalyst performance or chemical reactions. 6) Reduction reaction: When the medium on the tube side and shell side is mixed, it causes the chemical reaction to terminate or limit. 7) Product impurity: When the medium in the tube and shell is mixed, it can cause product contamination or a decrease in product quality.   6.1 Double tube sheet fixed tube sheet heat exchanger (Figure 9) 6.2 Double tube plate U-tube heat exchanger (Figure 10) 6.3 Double tube U-tube kettle reboiler (Figure 11)     7.Pulling tube sheet heat exchanger The pull-up tube sheet heat exchanger (Figure 12) has a thinner tube plate thickness, usually between 12 and 18mm.   7.1 The structural types include: (1) Face to face (Germany): The tube sheet is welded onto the sealing surface of the equipment flange (Figure 12a). (2) Inlaid type (former Soviet Union) ГОСТ Standard): The tube sheet is welded to the flat surface of the equipment flange sealing surface (Figure 12b). (3) Corner welding (formerly developed by Shanghai Pharmaceutical Design Institute): The tube sheet is welded to the shell (Figure 12c).   7.2 Scope of application: 1) Design pressure: The tube side and shell side shall not exceed 1.0 MPa respectively; 2) Temperature range: The design temperature range for the tube side and shell side is from 0 ℃ to 300 ℃; The average wall temperature difference between the heat exchange tube and the shell shall not exceed 30 ℃; 3) Diameter range: The inner diameter of the shell shall not exceed 1200mm; 4) Heat exchange tube length: not exceeding 6000mm. 5) Heat exchange tubes should be made of light tubes and have a linear expansion coefficient close to that of the shell material (the difference in values between the two should not exceed 10%). 7.3. Expansion joints should not be installed.     8. Flexible tube sheet heat exchanger Suitable for horizontal shell and tube residual (waste) heat boilers with gas as the medium on the tube side and saturated water vapor generated on the shell side. The connection between Type I tube sheet and shell (channel) (see Figure 13a) and the connection between Type II tube sheet and shell (channel) (see Figure 13b).   Applicable scope: 1) The design pressure of the tube side shall not exceed 1.0 MPa, the design pressure of the shell side shall not exceed 5.0 MPa, and the shell side pressure shall be greater than the tube side pressure; (1) Type I is used for pipe design pressure less than or equal to 0.6MPa; (2) Type II is used for piping design pressures less than or equal to 1.0 MPa. 2) The diameter of the shell and the length of the heat exchange tube are 2500mm and 7000mm, respectively.     9. Efficient spiral wounded tube heat exchanger In order to save equipment investment, the maximum heat transfer area of heat exchange tubes is arranged within the limited shell volume of the heat exchanger, and the heat transfer efficiency is improved. Therefore, the shell and tube wound tube heat exchanger (Figure 16) has emerged. This type of heat exchanger is a multi-layer multi head stainless steel small diameter heat exchange tube wound and welded on the core rod, as shown in Figure 16.   10. Austenitic stainless steel corrugated heat exchanger 1) Applicable scope: (1) The design pressure shall not exceed 4.0MPa; (2) The design temperature shall not exceed 300 ℃; (3) The nominal diameter shall not exceed 2000mm; (4) The nominal diameter shall not exceed 4000 times the product of the design pressure. 2) Inappropriate occasions (1) Media with extreme or highly hazardous toxicity; (2) Explosive media; (3) In situations where there is a tendency towards stress corrosion.     Wuxi Changrun has provided high-quality tube sheets, nozzles, flanges, and customized forgings for heat exchangers, boilers, pressure vessels, etc. to many well-known petrochemical enterprises at home and abroad. Our customers include PetroChina, Sinopec, Chevron, Bayer, Shell, BASF, etc. Send your drawings to sales@wuxichangrun.com We will provide you with the best quotation and the highest quality products.

A double tube sheet heat exchanger is a heat exchanger with two tube sheets with a certain gap at one end of the heat exchanger.   At the end of the heat exchange tube, there is a tube sheet called the outer tube sheet, also known as the tube side tube sheet, which serves as an equipment flange and is connected to the heat exchange tube and channel flange. There is also a tube sheet located closer to the end of the heat exchange tube, called the inner tube sheet, which is the shell side tube sheet, connected to the heat exchange tube and the shell side. There is a certain distance between the outer and inner tube sheets, and this space can be separated from the outside by a skirt segment, forming a pressure free isolation chamber; It can also be an open structure.     Application of double tube sheet heat exchanger In practical operation, double tube sheet heat exchangers are generally used in the following two situations: 1.One is to absolutely prevent the mixing of media between the shell and tube sides, for example, in heat exchangers where water flows through the shell side or chlorine or chloride flows through the tube side. If the water in the shell side comes into contact with chlorine or chlorides in the tube side, it will produce highly corrosive hydrochloric acid or hypochlorous acid, which will cause serious corrosion to the material of the tube side.   Adopting a double tube sheet structure can effectively prevent the mixing of two materials, thereby preventing the occurrence of the above-mentioned accidents.   2.Another scenario is when there is a large pressure difference between the medium on the tube and shell side. In this case, a medium is usually added to the cavity between the inner and outer tube sheets to reduce the pressure difference between the medium on the tube and shell side.   When the mixing of heat exchanger tube side and shell side media is strictly prohibited in the following situations, a double tube sheet structure is often used: ① When the two media of the tube side and shell side are mixed, it will cause serious corrosion; ② The infiltration of extremely or highly hazardous media on one side into the other can cause serious consequences; ③ When the medium on the tube side and the medium on the shell side are mixed, the two media will cause combustion or explosion; ④ When one medium mixes with another, it causes catalyst poisoning; ⑤ Mixing the tube side and shell side media can cause polymerization or the formation of resin like substances; ⑥ The mixing of the tube side and shell side media can cause the termination or restriction of chemical reactions; ⑦ The mixing of tube side and shell side media can cause product contamination or a decrease in product quality.     Comparison of double tube sheet and single tube sheet heat exchanger structures The double tube sheet heat exchanger adopts a fixed tube sheet structure, and the tube bundle cannot be extracted for cleaning. The single tube sheet heat exchanger can adopt a variety of structural types, and the tube bundle can be extracted for cleaning. For double tube sheet heat exchangers with large temperature differences, corrugated expansion joints can be installed on the simplified structure; for single tube sheet heat exchangers, in addition to installing corrugated expansion joints on the simplified structure, floating heads or U-shaped tubes are often used to compensate.   There are two design concepts for double tube sheet heat exchangers: one believes that double tube sheet heat exchangers are used to absolutely prevent the mixing of media between the tube and shell sides. A drainage and backflow valve is designed to be installed on the cavity between the inner and outer tube sheets for daily observation and discharge in case of leakage of the inner tube plate, so that the medium on the tube and shell side is effectively isolated by the inner and outer layer tube sheets. This is the main purpose of using a double tube sheet structure.   Another view is that double tube sheet heat exchangers can be used in situations where the pressure difference between the tube and shell side media is large. A medium is designed to be added to the cavity between the inner and outer tube sheets to reduce the pressure difference between the tube and shell side media. This is similar to a typical single tube sheet heat exchanger, and it cannot be absolutely guaranteed that there will be no leakage from the pipe opening on the outer tube sheet.     Comparison of the use of double tube sheet and single tube sheet heat exchangers Single tube sheet heat exchangers are the most common. In addition to frequent leakage of gaskets, bolts, flanges, and joint seals during use, there may also be leakage of pipe openings on the tube sheet, as well as welding cracks. Most of the pipe mouth leaks on the single tube sheet heat exchanger occur at the welding arc end. During welding, the gas was not completely discharged and there were sand holes.   The double tube sheet heat exchanger has inner and outer double tube sheets, and if there is a leakage at the inner tube sheet and tube ends, there is also an outer tube sheet protection.   Welding cracks in single tube plate heat exchangers often occur at the joint between the flange and the shell of the heat exchanger. The main reason for the problem here is that the stress at the junction between the flange and the cylinder is high; The second is the sudden change in geometric size and shape, which makes it easy to bury defects.   The joint between the simplified large flange and the cylinder of the double tube sheet heat exchanger is located on the outer edge of the cavity formed between the inner and outer tube sheets, and there is no medium in the cavity or the medium pressure is very low. The stress condition is better than that of a single tube sheet heat exchanger.   In addition, the pressure test of the double tube plate heat exchanger needs to be conducted 4 times (tube side, shell side between two inner tube plates, and cavity between inner and outer tube plates on both sides), while the pressure test of the single tube plate heat exchanger needs to be conducted 2-3 times (tube side, shell side or tube side, shell side, and small float).     Comparison of Manufacturing Double Tube Sheet and Single Tube Sheet Heat Exchangers ① Costs Compared with a single tube sheet heat exchanger, a double tube sheet heat exchanger adds two outer tube sheets, a cavity between the two inner and outer tube sheets, and heat exchange tubes in the cavity. At present, the price of double tube sheet heat exchangers ordered domestically is about 10-20% higher than that of single tube sheet heat exchangers ordered. If the double tube sheet structure and single tube sheet structure are used as heat exchangers respectively, the weight of the double tube sheet is increased by 10% to 20% compared to the single tube sheet, and the cost is increased by 25% to 37%. Therefore, more attention should be paid to the manufacturing quality of double tube sheet heat exchangers, so that more money can be spent to achieve good results.   ② Expansion joint Usually, there are roughly four forms of connection between heat exchange tubes and tube sheets, namely strength welding (commonly argon arc welding), strength expansion, strength welding+adhesive expansion, and strength expansion+sealing welding. The differences are mainly reflected in whether the tube holes are slotted, the welding groove, and the length of the tube extension. Expansion joints can be divided into non-uniform expansion joints (mechanical ball expansion joints), uniform expansion joints (hydraulic expansion joints, liquid bag expansion joints, rubber expansion joints, explosive expansion joints, etc.).   The design of the double tube sheet heat exchanger requires strength welding and strength expansion, and it is recommended to use the hydraulic expansion method. The general design requirement for single tube sheet heat exchangers is to use strength welding and adhesive expansion, and mechanical or manual expansion can be used.   At present, most domestic manufacturers do not have hydraulic expansion equipment. Even if they do, due to the high cost of purchasing hydraulic expansion heads and high losses (with an average expansion of over 100 pipe openings, a new hydraulic expansion head is required). Hydraulic expansion head is disposable and cannot be repaired.   Therefore, hydraulic expansion tube method is rarely used to manufacture heat exchangers.   Wuxi Changrun has provided high-quality tube sheets, nozzles, flanges, and customized forgings for heat exchangers, boilers, pressure vessels, etc. to many well-known petrochemical enterprises at home and abroad. Our customers include PetroChina, Sinopec, Chevron, Bayer, Shell, BASF, etc. Send your drawings to sales@wuxichangrun.com We will provide you with the best quotation and the highest quality products.  

The characteristics of ASTM A182 F5 flange The ASTM A182 F5 Flange is constructed of chromium molybdenum steel. It is lightweight and has a high rupture resistance. It is also resistant to hydrogen attack and cracking caused by sulfide corrosion. The material Alloy Steel ASTM A182 F5 Flanges is widely used in the petrochemical and power generation industries. These flanges are widely used in a variety of industries such as power generation, gas processing, oil drilling, pharmaceuticals, and seawater equipment.   Slip-on and threaded ASTM A182 F5 Flanges are also available. Flanges made of alloy steel grade F5 and alloy steel grade F9 are suitable for high temperatures and pressure. These flanges are built to withstand high pressures and are made from high-quality raw materials. As a result, they are the preferred option for any industrial project.     ASTM A182 F5 Flanges chemical composition and mechanical properties The ASTM A182 F5 specification covers requirements for F5 alloy steel forgings and forged products such as chemical composition, mechanical properties, heat treatment, and other supplementary requirements.     ASTM A182 F5 flange usage range ASTM A182 F5 Flanges are available in nominal bore sizes ranging from 1/2-inch to 36-inch. They come in a variety of pressure ratings and are typically used in smaller piping systems. They are also used in high-risk environments where welding connections would be hazardous. Look no further than our ASTM A182 F5 Flange if you need high-quality flanges.     ASTM A182 F5 Weld-neck Flanges are used in industrial, high-pressure applications such as condensers, boilers, evaporators, heat exchangers, and so on. Also, Wuxi changrun offer a wide range of Alloy Steel ASTM A182 F5 Flanges such as ASTM A182 F5 Slip On Flanges, Alloy Steel F5 Weld Neck Flanges, F5 Alloy Steel Socket Weld Flanges, A182 F5 Alloy Steel Blind Flanges, Alloy Steel F5 Orifice Flanges, A182 Alloy Steel F5 Spectacle Blind Flanges, A182 F5 Screwed / Threaded Flanges, Alloy Steel F5 Reducing Flanges, ASTM A182 F5 Alloy Steel Ring Type Joint Flanges (RTJ), etc.      Wuxi Changrun has provided high-quality tube sheets, nozzles, flanges, and customized forgings for heat exchangers, boilers, pressure vessels, etc. to many well-known petrochemical enterprises at home and abroad. Our customers include PetroChina, Sinopec, Chevron, Bayer, Shell, BASF, etc. Send your drawings to sales@wuxichangrun.com. We will provide you with the best quotation and the highest quality products.    

What is heat exchanger baffle? A heat exchanger baffle is a plate or barrier that is inserted into a heat exchanger to enhance heat transfer efficiency. The primary function of a baffle is to direct the flow of fluid inside the heat exchanger in a specific pattern, such as cross-flow or counter-flow, to maximize heat transfer.   Baffles are commonly used in shell and tube heat exchangers, which consist of a bundle of tubes enclosed in a shell. The baffles are placed inside the shell, perpendicular to the tube bundle, and divide the shell into several chambers. The fluid flows through the tubes and is directed by the baffles through each chamber, which increases the time the fluid spends in contact with the tube surface, thereby enhancing heat transfer efficiency.       The types of baffle plates The design and placement of baffles in a heat exchanger depend on the specific application requirements, including the type of fluid being heated or cooled, the flow rate, temperature, and pressure, and the desired heat transfer rate. The size, shape, and thickness of the baffles may also vary depending on the application. The baffle plate is installed on the shell side, which can not only improve heat transfer efficiency but also play a role in supporting the tube bundle. There are two types of baffles: arched and disc-shaped. Arched baffles are available in three types: single arched, double arched, and triple arched.     What is the function of a baffle? 1. Extend the flow channel length of the shell side medium, increase the flow velocity between tubes, increase the degree of turbulence, and achieve the goal of improving the heat transfer efficiency of the heat exchanger.   2. Setting baffle plates has a certain supporting effect on the heat exchange tubes of horizontal heat exchangers. When the heat exchange tube is too long and the pressure stress borne by the tube is too high, increasing the number of baffle plates and reducing the spacing between baffle plates while meeting the allowable pressure drop of the heat exchanger tube side can play a certain role in alleviating the stress situation of the heat exchange tube and preventing fluid flow induced vibration.   3. Setting baffle plates is beneficial for the installation of heat exchange tubes.       Heat exchange baffles can be made of various materials, such as stainless steel baffle plates, carbon steel baffle plates, or titanium baffle plates, depending on the corrosive or erosive nature of the fluid being processed. In some cases, baffles may also have holes or slots to allow for more fluid flow and heat transfer.   Wuxi Changrun has provided high-quality baffle plate, tube sheets, nozzles, flanges, and customized forgings for heat exchangers, boilers, pressure vessels, etc. to many well-known petrochemical enterprises at home and abroad. Our customers include PetroChina, Sinopec, Chevron, Bayer, Shell, BASF, etc. Send your drawings to sales@wuxichangrun.com We will provide you with the best quotation and the highest quality products.  

What are the tube sheet inspection and testing methods? Tube sheet inspection and testing methods are used to ensure the integrity and safety of tube sheets, which are components used in heat exchangers and other types of equipment. There are several methods used for tube sheet inspection and testing, including:   Visual Inspection This is the simplest method of tube sheet inspection, which involves a visual examination of the tube sheet surface for any visible cracks, corrosion, erosion or other signs of damage.   Dye Penetrant Test (PT) This method involves applying a dye penetrant to the surface of the tube sheet and then wiping off the excess. The penetrant is then drawn into any cracks or other surface defects by capillary action. A developer is applied, which draws the penetrant out of the cracks and makes them visible.   Magnetic Particle Test (MT) This method involves applying a magnetic field to the tube sheet and then applying ferromagnetic particles to the surface. Any surface cracks or defects will cause the magnetic field to be distorted, making the particles cluster at the location of the defect, which can then be visually detected.   Ultrasonic Testing (UT) This method uses high-frequency sound waves to detect defects in the tube sheet. A probe is placed on the surface of the tube sheet, which emits sound waves that travel through the material. Any defects in the material will cause some of the sound waves to be reflected back to the probe, which can be detected and analyzed.   Eddy Current Testing (ECT) This method involves passing an alternating electrical current through a coil, which induces eddy currents in the tube sheet. Any defects in the material will cause changes in the eddy currents, which can be detected and analyzed.   These methods can be used individually or in combination to provide a comprehensive inspection and testing of tube sheets. The choice of method(s) used will depend on the type of equipment, the material of the tube sheet, and the level of sensitivity required for defect detection.   Wuxi Changrun has provided high-quality tube sheets, nozzles, flanges, and customized forgings for heat exchangers, boilers, pressure vessels, etc. to many well-known petrochemical enterprises at home and abroad. Our customers include PetroChina, Sinopec, Chevron, Bayer, Shell, BASF, etc. Send your drawings to sales@wuxichangrun.com We will provide you with the best quotation and the highest quality products.    

What is double tube sheet? A double tube sheet is a design feature commonly used in shell-and-tube heat exchangers and other similar equipment. In a shell-and-tube heat exchanger, there are two main components: the shell, which is a large outer vessel, and the tubes, which are smaller tubes that run through the shell. The double tube sheet design involves having two separate tube sheets within the shell.     Double tube sheet heat exchangers are generally used in the following two situations: One is to absolutely prevent the mixing of media between the shell and tube sides. For example, for heat exchangers with water passing through the shell side or chlorine gas or chloride passing through the tube side, if the water in the shell side comes into contact with chlorine gas or chloride in the tube side, it will produce highly corrosive hydrochloric acid or hypochlorous acid, which will cause serious corrosion to the material in the tube side. Adopting a double tube sheet structure can effectively prevent the mixing of two materials, thereby preventing the occurrence of the above-mentioned accidents;   Another scenario is when there is a large pressure difference between the medium on the tube and shell side. In this case, a medium is usually added to the cavity between the inner and outer tube sheets to reduce the pressure difference between the medium on the tube and shell side. This series of heat exchangers adopts a double tube plate structure design, which connects the tube side and shell side with their respective tube sheets, breaking the traditional practice of using the same connecting tube plate for both the tube side and shell side of a row tube heat exchanger. This minimizes the risk of cross contamination, facilitates timely detection of leakage hazards, and ensures safe production for users.     How double tube sheet works? 1. Inner Tube Sheet: The first tube sheet is located inside the shell and is usually closer to one end. The tubes are attached to this inner tube sheet, and they pass through it to the other end of the shell.   2. Baffle Space: Between the inner tube sheet and the other end of the shell, there is a space that contains baffles. Baffles are plates or other structures designed to direct the flow of the fluid inside the shell and promote efficient heat transfer.   3. Outer Tube Sheet: The second tube sheet is located at the other end of the shell. The tubes are also attached to this outer tube sheet.     Whats the double tube sheet design advantages? 1. Prevents Cross-Contamination: Because there are two tube sheets, there is a space (the baffle space) between them. This helps to prevent cross-contamination between the two fluids flowing through the tubes, especially when they have different properties.   2. Enhanced Safety: In applications where one fluid is hazardous or toxic, the double tube sheet design provides an extra layer of safety by reducing the risk of leaks.   3. Reduced Risk of Thermal Expansion Issues: The double tube sheet design helps accommodate thermal expansion differences between the tubes and the shell. This is important to avoid problems that may arise from temperature-induced expansion and contraction.   4. Easier Inspection: The space between the tube sheets allows for easier inspection of the tubes and facilitates maintenance activities.     In summary, a double tube sheet design is a configuration used to enhance the safety, efficiency, and ease of maintenance in certain types of heat exchangers, particularly those dealing with potentially hazardous fluids.   Wuxi Changrun has provided high-quality tube sheets, nozzles, flanges, and customized forgings for heat exchangers, boilers, pressure vessels, etc. to many well-known petrochemical enterprises at home and abroad. Our customers include PetroChina, Sinopec, Chevron, Bayer, Shell, BASF, etc. Send your drawings to sales@wuxichangrun.com We will provide you with the best quotation and the highest quality products.    

A shell and tube heat exchanger consists of a shell, heat transfer tube bundle, tube sheet, baffle plate (baffle), and channel. The shell is mostly cylindrical with a tube bundle inside, and the two ends of the tube bundle are fixed on the tubesheet. There are two types of heat transfer fluids: hot fluid and cold fluid. One is the fluid inside the tube, called the tube side fluid; Another type is the fluid outside the pipe, called the shell side fluid.     1. What is Shell? The shell serves as the outer housing of the heat exchanger. It contains one of the fluid streams and is typically constructed from materials such as carbon steel, stainless steel, or other alloys depending on the application and operating conditions.   2. What is Tube Bundle? The tube bundle is the core component of the heat exchanger where heat transfer occurs. It consists of a series of tubes through which one fluid flows while the other fluid flows around the outside of the tubes. The tubes can be straight or bent, and they are usually made of materials such as copper, stainless steel, or titanium.   3. What is Tubesheet? The tubesheet is a thick metal plate located at both ends of the tube bundle. It serves to support and secure the tubes in place, providing a leak-proof seal between the tube bundle and the shell.   4. What are Baffles? Baffles are plates or spacers placed inside the shell to direct the flow of the shell-side fluid. They promote turbulence in the fluid flow, which enhances heat transfer efficiency by increasing the mixing of the fluid. Baffles also help to support the tubes and prevent vibration.   5. What is Baffle Plate? The baffle plate is a large plate attached to the inner wall of the shell. It supports the baffles and helps to guide the flow of the shell-side fluid through the heat exchanger.   6. What is Front Channel and Rear Channel? These are the spaces between the baffles where the shell-side fluid flows around the tube bundle. The front channel is located near the inlet of the shell-side fluid, while the rear channel is located near the outlet.   7. What is Tube Side Connection? These are the inlet and outlet connections for the fluid flowing through the tubes. They allow the tube-side fluid to enter and exit the heat exchanger.   8. What is Shell Side Connection? These are the inlet and outlet connections for the fluid flowing around the outside of the tubes. They allow the shell-side fluid to enter and exit the heat exchanger.   9. What is Vent? The vent is an opening on the shell of the heat exchanger used to remove trapped air or gases during startup or operation. It ensures proper operation and prevents air pockets from interfering with heat transfer.   10. What is Drain? The drain is an opening on the shell or tubesheet used to remove liquid from the heat exchanger. It is typically used for maintenance purposes or for draining the system during shutdowns.   11. What is Expansion Joint? An expansion joint is a flexible element installed in the shell or tube bundle to accommodate thermal expansion and contraction. It prevents damage to the heat exchanger caused by temperature fluctuations.   12. What are Heat Exchanger Legs? Legs are support structures attached to the bottom of the heat exchanger to elevate it above the ground or other surfaces. They provide stability and facilitate installation and maintenance.   13. Lifting Lug? Lifting lugs are welded to the shell of the heat exchanger and used for lifting and handling during installation or maintenance.   14. Reinforcing Pad? Reinforcing pads are additional material welded to the shell or other components to strengthen areas subjected to high stress or pressure, such as nozzle connections.   These components work together to facilitate efficient heat transfer between the two fluid streams while ensuring structural integrity, reliability, and safety of the heat exchanger.    Wuxi Changrun has provided high-quality tube sheets, nozzles, flanges, and customized forgings for heat exchangers, boilers, pressure vessels, etc. to many well-known petrochemical enterprises at home and abroad. Our customers include PetroChina, Sinopec, Chevron, Bayer, Shell, BASF, etc. Send your drawings to sales@wuxichangrun.com We will provide you with the best quotation and the highest quality products.