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What is shot peening? Shot peening is a process that uses a high-speed rotating impeller to shoot the shot out at high speed, hit the workpiece surface, and clean or strengthen the workpiece surface. The materials used for shot peening include steel shot, aluminum shot, glass ball and ceramic shot. Characteristics of shot peening 1) High cleaning efficiency, low cost, few operators, easy to realize mechanization, suitable for mass production; 2) No compressed air is used to accelerate the projectile, so there is no need to set up a high-power air compression station, and the cleaned surface is free of moisture; 3) Poor flexibility, limited by the site, some blindness when cleaning the workpiece, and it is easy to produce dead corners on the workpiece surface that cannot be cleaned; 4) The equipment structure is complex, there are many vulnerable parts, especially the blades and other parts wear fast, there are many maintenance hours and high costs; 5) Generally, light and small projectiles cannot be used. Shot peening process Shot peening is also the name of a mechanical surface treatment process, similar to sand peening and shot peening. Shot peening is a cold treatment process, which is pided into shot peening cleaning and shot peening strengthening. Shot peening cleaning, as the name implies, is to remove surface oxide and other impurities to improve the appearance quality. Shot peening strengthening is to use high-speed motion of the projectile (60-110m/s) flow to continuously impact the surface of the strengthened workpiece. The target surface and surface layer (0.10-0.85mm) are forced to undergo the following changes during cyclic deformation: 1. Modification of microstructure; 2. Non-uniform plasticized outer surface introduces residual compressive stress and inner surface produces residual tensile stress; 3. The outer surface roughness changes (Ra Rz). Impact: it can improve the fatigue fracture resistance of materials/parts, prevent fatigue failure, plastic deformation and brittle fracture, and improve the fatigue life. Structure principle The two disks in the shot peening device are riveted together to form an impeller body. The impeller body is provided with eight blades, and the impeller body and the shot splitting wheel located in the center of the shot peening wheel are mounted on the main shaft driven by an electric motor. The cover is lined with a guard plate, and the cover shell is provided with a directional sleeve and a shot tube. When working, the shot from the shot tube into the shot peening device. The projectile wheel, which rotates synchronously with the blades, gives the projectile its initial velocity. The projectile flies out of the window of the directional sleeve and is thrown to the high-speed rotating blade outside the directional sleeve. After being further accelerated by the blade, it is thrown onto the surface of the cleaned workpiece. Because the synchronous rotation of the shot wheel and the blade ensures the non-vibration transmission of the projectile to the blade, thus reducing the wear of the blade. Peening principle is the body of the motor to drive the impeller rotation (direct drive or use the “V” belt drive), by the effect of centrifugal force, the diameter is about 0.2 ~ 3.0 of the projectile (have pills for cast steel, steel cut wire shot, stainless steel, such as different types) to the surface of the workpiece, the workpiece surface reaches a certain roughness, makes the artifacts become beautiful, Or change the welding tensile stress of the workpiece to compressive stress, improve the service life of the workpiece. By improving the surface finish of the workpiece, the film adhesion of the subsequent painting of the workpiece is also improved. Shot peening is almost used in most fields of machinery, such as shipbuilding, automobile parts, aircraft parts, surface of guns and tanks, Bridges, steel structures, glass, steel plate profiles, pipe internal and external wall corrosion and even road surface and so on. Bring about shot peening machine Shot peening machine is a kind of processing technology which impacts steel sand and steel shot on the surface of material object at high speed by shot peening device. It is faster and more efficient than other surface treatment techniques, and allows for partial retention or stamping after the casting process. Shot peening machine can also be used to remove burrs, diaphragms and rust, shot peening machine can also be directed at a partially coated surface to remove surface contaminants and provide an increase in coating adhesion surface profile, to achieve the purpose of strengthening the workpiece. Shot peening equipment is first applied to the surface of cast steel, cast iron sand and oxide cleaning. Almost all steel castings, gray castings, ductile iron and so on should be shot peening. This is not only to remove the oxide scale and sand on the surface of the casting, but also an indispensable preparation process before the quality inspection of the casting. For example, before the non-destructive inspection of the large gas turbine casing, strict shot peening cleaning must be carried out to ensure the reliability of the inspection results. Casting shot peening In general casting production, shot peening is an essential technological means to find surface defects of castings such as subcutaneous pores, slag holes, sand sticking, cold insulation, peeling, etc. The surface cleaning of non-ferrous metal castings, such as aluminum alloy and copper alloy, in addition to removing the oxide scale and finding the surface defects of the castings, the main purpose is to remove the burr of the die-casting parts by shot peening and obtain the surface quality with decoration significance, so as to achieve comprehensive results. Mechanical adjustment The new shot peening device must correctly adjust the position of the directional sleeve window before use, so that the projectile thrown as much as possible to be cleaned on the surface of the workpiece, in order to ensure the cleaning effect, reduce the wear of the indoor wall wear parts. The position of the directional sleeve window can be adjusted by referring to the manual. Shot peening material Common shot peening materials are steel shot, aluminum shot, ceramic powder, steel sand, walnut sand, corn cob, glass beads, resin sand, plastic sand and so on. Source: China Pipe Fittings Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

For the skilled copper pipe installer, there are a variety of copper pipe connection options available. Not only are there the normal brazed joints, but there are also the excellent performance sleeve joints. We can make joints directly on the pipe and then weld them using hard brazing or bronze welding techniques, or we can use copper and copper alloy brazed sleeves. We can also use a variety of extruded joints. All of these copper pipe connections have been continuously developed and perfected, and they are completely reliable for qualified professional installers. In addition, the combination of copper and casing characteristics allows for long-term, reliable, safe and economical operation of gas, water supply, sewerage, and heating facilities. Mechanical connection Non-processing compression type connection The use of non-processing compression fittings to implement the mechanical connection of copper pipes, is a relatively simple construction method, simple operation, easy to grasp, the construction personnel only need a little training, you can master the operating skills. It is a common connection method in the current project. When connecting, as long as the end face of the pipe cutout can be kept vertical with the axis of the pipe, and the cutout burr and other clean, pipe assembly is the correct position of the card ring placement, and tighten the nut, you can achieve a tight connection of copper pipe. But this connection, is to rely on the thread on the compression force of the ring to keep the joint tight, so the joint should not be directly buried in the wall, it is advisable to lay the joint in the location can be serviced, so that once the compression force is slack and leakage, by further tightening the nut to maintain the necessary pressure. Processing compression type connection The use of processing compression fittings to implement the mechanical connection of copper pipe, is also one of the common construction methods of copper pipe connection, which is different from the construction method of non-processing compression connection, is that the end of the copper pipe must be shaped and processed before construction, that is, the construction of copper pipe, the end of the tube after cutting correction, but also need to use special forming tools, the end of the pipe processing bracket into a cup or cone, and the shape of the cup or cone, the size needs to be Standardized and unified. Because the connection of processing compression copper pipe fittings, is to rely on the cup or conical end of the pipe directly with the copper pipe fittings corresponding to the sealing surface to the tightness of the pipe joint, copper pipe end forming norms or not, directly affect the quality of the joint connection, therefore, engaged in copper pipe processing compression mechanical connection construction personnel, should be the necessary technical training, mastering the processing skills of forming before engaging in construction, in order to ensure that the processing of compression type connection construction quality. Flange and groove type connection The connection between the larger diameter copper pipe, copper pipe and valve fittings, as well as copper pipe and equipment, containers, the connection between the general use of flange connection, that is, copper pipe by brazing brass flange, or processing into the form of flanged plus steel flange, the formation of flange type joint, there are bolts and nuts to implement the flange connection. The connection between the larger diameter copper pipe, can also be used groove type connection, that is, the use of special groove forming machinery, the end of the copper pipe tied a depth and width in line with the standard groove connection ring groove, and then use the groove connection fittings, the two copper pipe connected into one. Using this connection, the wall thickness of the copper pipe must comply with the relevant standards. Copper and non-copper groove connection fittings contact surface, should be taken to isolate measures to prevent galvanic corrosion. Plug-in connection The use of plug-in copper fittings to implement the mechanical connection of copper pipes, is currently one of the simple construction methods, simple and convenient operation, the construction personnel only need to be familiar with its operational requirements, a little practice can be mastered. When connected, the end face of the pipe incision should be perpendicular to the axis of the pipe, the burr inside and outside the incision should be cleaned up, and marked with a marker on the outside of the front of the copper pipe to insert the depth, and then force the copper pipe into the pipe fittings to the end to stop the pipe. This bell connection method is to rely on special fittings in the stainless steel clamping ring to fasten the copper pipe in the fittings, the use of fittings and the outer wall of the copper pipe closely with the “O” rubber ring to implement the seal to complete the tight connection of the copper pipe. When using the plug-in connection method, the copper pipe can not be inserted once the exit, such as installation errors need to be changed, you must check the fittings to be sure there is no damage to use again. Crimp connection Using crimped copper fittings to implement the crimp connection of copper pipes, is one of the newer construction methods, operation is also simple, but need to be equipped with special and complete specifications of crimping machinery. Connection, the pipe notch end face should be perpendicular to the axis of the pipe, the burr inside and outside the notch should be cleaned, and then insert the pipe into the pipe fittings in the end, and gently turn the pipe, so that the pipe and pipe fittings with concentric segments, and then crimping machinery with special copper pipe and pipe fittings crimped into one. This bell connection method, is the use of cold crimping technology to make the copper pipe and pipe fittings into one, the use of rubber seals within the flange of the pipe to implement the seal, complete the tight connection of copper pipe. The use of crimping connection method, pipe laying is very convenient, before crimping, copper pipe and pipe fittings can be freely disassembled, as long as the time of crimping is properly selected, it can make the installation in one step. Brazing connection The principle and characteristics of brazing A. Definition of brazing Brazing is the use of brazing material with a lower melting point than the base material and the base material together with the heating, in the case of the base material does not melt, the brazing material melted wetting and filling into the gap between the two base material connections, forming a brazing seam, in the gap, the brazing material and the base material dissolve and diffuse each other, so as to get a solid bond. Brazing can be pided into two categories according to the melting point of the brazing material used, generally 450°C as the boundary, brazing material melting point <450°C brazing for soft brazing, brazing material melting point >450°C brazing for hard brazing. Soft brazing is simple to operate and easy to master, but its joints. B. Characteristics of brazing Firstly, the base material does not melt when brazing, but only the brazing material melts. Secondly, in brazed joints, the brazing material composition and properties are significantly different from the base material, and the melted brazing material needs to fill the gap of the pro-joint by capillary action and improve its load-bearing capacity by the lap area of the joint. The main features of brazing are lower heating temperature, smaller changes in the organization and mechanical properties of the welded parts, flat and smooth joints, little deformation, and the possibility of connecting different materials, high productivity. Therefore, brazing is widely used in the construction of copper pipes. However, the strength of brazed joints is directly affected by the size of the joint assembly gap. Some test data prove that the strength of brazed joints decreases with the increase of the device gap, and the size of the gap also affects the capillary action and brazing area, so the brazed joint assembly should be maintained with a uniform and strict gap to ensure the quality of the brazed joint. C. The formation process of brazed joints The formation process of brazed joints is that the base material and brazing material are heated to the brazing temperature, the brazing material melts and flows into the gap of the joint while interacting with the base material to form a new alloy, and then cools and crystallizes in the brazing gap to form a brazed joint. Therefore, the key to a solid joint is that the melted brazing material flows well into the gap to fill the brazing joint and interacts with the base material and cools and crystallizes. In brazing, the gap of the brazing seam is small, and the brazing material needs to flow in the brazing seam under capillary action, which is only formed when the liquid brazing material can wet the surface of the base material, so the wetting of the base material by the liquid brazing material is the key to whether the brazing material can flow into the brazing seam and fill the brazing seam. Only when the liquid brazing material can dissolve or form a compound with the base material, the brazing material can wet the base material better. Therefore, it is necessary to choose a suitable brazing material so that the liquid brazing material can have sufficient wetting to the base material. The tin brazing material, silver brazing material and copper phosphorus brazing material selected for copper tube brazing have quite good wettability for copper. Secondly, the influence of the oxide on the surface of the base material, the oxide on the surface of the metal prevents the atoms of the brazing material from coming into direct contact with the base material, so that the liquid brazing material is agglomerated into spheres under the action of surface tension, forming a non-wetting phenomenon. Therefore, the oxides on the surface of the base material should be removed during brazing, including those generated during the brazing process, so that the brazing material maintains wettability to the base material. A common method is to choose a suitable brazing flux to effectively remove the oxide. Type and selection of brazing material and brazing flux A. The type and selection of brazing material Brazing material, also known as solder, is a metal or alloy that melts and fills into the brazed joint at a temperature lower than the melting temperature of the base material when brazing. The brazing materials used for brazing copper pipes are as follows. (1) Tin brazing solder tin brazing solder is mainly composed of tin-lead, tin-antimony, tin-silver and other alloys, which are soft brazing solder with low brazing temperature, good wettability and easy operation, but the joint strength is low and the temperature resistance is poor, mainly used for brazing of small diameter copper water pipes below 2″. (a) Tin-lead solder, commonly used is tin-lead solder with 50% of tin-lead each, its melting temperature is 210°C, solidification temperature is 183°C. Because the excessive lead in the solder will affect the water quality in the pipe, it is not suitable for use in domestic water supply pipes, and can be used in drainage pipes. (b) Pure tin brazing material, generally the tin brazing solder containing more than 90% tin is called pure tin brazing material. But high-purity tin can not be used as brazing material, because pure tin is white at room temperature, once the temperature drops low enough, it will change to gray, the volume increases by about 25%, which will turn white tin into gray powder, commonly known as “tin epidemic”. Therefore, pure tin solder must be added to 3-5% antimony, or the right amount of lead to prevent tin plague. Its melting temperature is 222°C, solidification temperature is 183°C, is the current tin brazing solder for copper water pipes. (c) Tin-silver brazing material, an alloy composed of 96% tin and 4% silver, with a melting temperature of 225°C and a solidification temperature of 221°C. If the silver improves the heat resistance of the brazing material and the strength of the brazing joint, it is a more ideal tin brazing material for brazing copper water pipes. Don’t market the increase in solidification temperature, in the adjacent joints need to successively braze to bring convenience, can be used in the first welding head in the tin-silver brazing material, after welding head in the use of pure tin brazing material, to avoid after welding head heating temperature on the first welding head to produce adverse effects. (2) Silver brazing material silver brazing material is mainly composed of silver-copper, silver-copper-tin, silver-copper-zinc and other alloys, is a hard brazing material, with high strength brazing joints, good wettability and other characteristics, but the brazing temperature is high, the operation is difficult, mainly for more than 2 “large diameter copper tubes and brazing joints with high quality requirements and brazing rate requirements. (3) Copper phosphorus brazing material copper phosphorus brazing material is composed of copper phosphorus binary alloy, is a hard brazing material, because phosphorus can reduce copper oxide, so the use of copper phosphorus brazing material brazing copper without additional brazing flux, brazing process performance, and cheap, so inappropriate to use tin brazing solder brazing copper tube is widely used. B. Types and selection of brazing flux Brazing flux is also called brazing solvent, whose main function is to remove the oxide film on the surface of the base material and brazing material, inhibit the re-oxidation of the base material and brazing material in the brazing process, so as to improve the wetting effect of brazing material on the brazed material. Therefore, the brazing flux should have sufficient ability to remove the oxide film on the surface of the base material and brazing material, and the melting point and active temperature of the brazing flux should be lower than the melting point of the brazing material and have sufficient stability in the brazing temperature range. The brazing fluxes used for brazing copper tubes are as follows. (1) Tin brazing with brazing flux Tin brazing can use organic brazing fluxes such as rosin. However, its activity is poor, and it is difficult to adapt to the requirements of copper brazing. Therefore, inorganic brazing fluxes consisting of inorganic salts such as zinc chloride are mostly used for tin brazing of copper pipes. Commonly used are solder paste and liquid brazing flux supplied by the market, and can also be configured by themselves. (2) Silver brazing with brazing flux copper tube silver brazing, must use the market supply of powdered silver brazing special brazing flux. It can be used directly, or can be made into a paste and then used. (3) Copper brazing with brazing flux using copper phosphorus brazing material welding purple copper, generally can be used without brazing flux. However, when brazing copper tubes and brass and other copper alloys, copper brazing flux is also required, and the main component of copper brazing flux is borax, which can be used in bottles of copper soldering powder supplied by the market, and can also be configured by itself, and should be modulated into a paste when used. The types and applications of copper brazing connection A. Tin brazing connection of copper pipes tin brazing connection of copper pipes is soft brazing, although the brazing temperature is low and the operation is simple, but the strength of the joint is low and the temperature resistance is poor, so it is mainly used in pipes with medium of water below 2″, such as hot and cold water supply and drainage pipes and air-conditioning water pipes, etc. (1) Ordinary welding type brazing requires the operator to add solder from the outside of the pipe and dissolve it into the gap, and form a brazed joint after cooling and crystallization. The quality of the brazed joint needs to be determined by the operating skills. (2) Built-in tin ring type built-in tin ring type pipe is in the production, the casing of the pipe at the inside of the pressed a ring-shaped groove, and cast in the groove with the inner wall of the pipe flush with the tin brazing solder, brazing, no need to add solder, only the implementation of heating at the joint, heating can be conventional flame heating method, can also use the electric heating method, that is, the use of special electric heating clamp held at the joint, and then energized Heating, so that the tin brazing material ring in the groove of the tube dissolves and fills the gap at the joint, and then brazes the joint after cooling and crystallization. The quality of brazed joints is easy and the operating skills required are low, but the cost is high. B. Phosphor bronze brazing connection of copper tube Phosphor bronze brazing connection of copper pipe is hard brazing, the joint strength is higher, temperature resistance is better, suitable for brazing connection of small and large diameter copper pipes of various media, but its brazing temperature is higher, and the requirement of operation skills is higher. Because when brazing, the temperature of the joint directly affects the phosphorus copper brazing material on the wettability of the copper tube, as well as the brazing material in the brazing seam mobility, especially in the brazing of large-diameter copper tubes, to make phosphorus copper brazing material can be better dissolved into the brazing seam, must control the heating temperature of the joint, and can maintain a good joint in the circumferential and length direction temperature uniformity, if there is a local temperature of overheating or too low, will affect the joint in the brazing material If the local temperature is too hot or too low, it will affect the flow of brazing material in the joint, thus affecting the quality of the brazed joint. C. Silver brazing connection of copper tubes Although the brazing temperature is high and the operation is difficult, the silver brazing material has better wettability and fluidity compared with the phosphor bronze brazing connection under the same brazing conditions, which makes it easier to melt into and fill the brazing seam, thus making it easier to get the quality of the brazed joint. This makes it easier to guarantee the quality of brazed joints. Processing methods of copper tubes There are many methods of processing copper tubes, but they can be pided into two categories: hot processing and cold processing. Such as extrusion manufacturing billet, oblique rolling perforation and other methods are heated to much higher than the recrystallization temperature of copper billet for deformation processing, so as to get the billet. The billet is then made into a tube at room temperature by cold rolling and cold drawing methods. This traditional process has been used for many years and is still in use today. The production process is to melt and cast electrolytic copper into solid ingots, and then heated to more than 850°C in the heating furnace, one by one into the extrusion machine extrusion into billets, and then through cold rolling or multiple linear stretching to disc stretching required billets. Extrusion is pided into two kinds of high extrusion ratio and low extrusion ratio, both of which have refined grain organization and good surface quality. High extrusion ratio extrusion billet specifications are small, thin wall thickness, can be directly in the continuous direct machine or disc stretching machine for processing; low extrusion ratio extrusion can be used for large ingot extrusion large specifications billet, and then extended processing with cold rolling mill. For the same size and specifications of the ingot, high extrusion ratio requires a larger extrusion tonnage, and extrusion of the tube wall thickness tolerance is large. At present in China is very popular is the continuous casting and rolling supply method, this is a new supply method in the 1990s, its production process is the horizontal continuous casting of hollow tube billet cut off the milling surface directly into the three-roller planetary rolling mill to roll out smaller diameter thin-walled copper pipe. As the three-roller mill can make the rolled copper tube without rotation, so it is easy to reel online into a tray. It is characterized by a short production process, eliminating the reheating and extrusion process, whether in saving energy, reducing equipment investment, reducing costs in all methods have the advantage.

What is shot peening? Shot peening uses the high-speed rotating impeller to throw out small steel shot or small iron shot and impact the part surface at high speed, so the oxide layer on the part surface can be removed. At the same time, steel shot or iron shot impacts the part surface at high speed, resulting in lattice distortion and deformation on the part surface and increasing the surface hardness. Shot peening is a method to clean the part surface. Shot peening is often used to clean the casting surface or strengthen the part surface. Generally, shot peening is used for regular shapes. Several throwing heads are up, down, left and right together, with high efficiency and little pollution. In the shipbuilding industry, shot peening and sand blasting are widely used. Shot peening uses the high-speed rotating impeller to throw out the abrasive; Sand blasting is the use of compressed air to blow out the abrasive at high speed. Of course, shot peening does not have to use a high-speed rotating impeller. In the repair and shipbuilding industry, generally speaking, shot peening (small steel shot) is mostly used in steel plate pretreatment (rust removal before coating); Sand blasting (mineral sand is used in repair and shipbuilding) is mostly used in formed ships or sections to remove the old paint and rust on the steel plate and repaint it. In the repair and shipbuilding industry, the main function of shot peening and sand blasting is to increase the adhesion of steel plate coating paint. The research shows that in terms of damage, when there is tensile stress on the surface of metal materials, it is much easier than compressive stress. When there is compressive stress on the surface, the fatigue life of materials is greatly improved. Therefore, shot blasting is usually used to form surface compressive stress for parts prone to fatigue fracture such as shafts, so as to improve the product life. In addition, metal materials are very sensitive to tension, This is the reason why the tensile strength of materials is much lower than the compressive strength. This is also the reason why metal materials generally use tensile strength (yield, tensile) to represent material properties. The steel plate working face of our daily car is strengthened with shot blasting, which can significantly improve the fatigue strength of the material. Shot peening uses the motor to drive the impeller body to rotate, and by the action of centrifugal force, throws the balls (including cast shot, cut shot, stainless steel shot, etc.) with a diameter of 0.2 – 3.0 to the surface of the workpiece, so as to make the workpiece beautiful, or change the welding tensile stress of the workpiece to compressive stress, so as to improve the service life of the workpiece. Almost used in most fields of machinery, such as repair, shipbuilding, auto parts, aircraft parts, gun and tank surfaces, bridges, steel structures, glass, steel plates, pipelines, etc. Sand blasting (shot) uses compressed air as power to spray sand with a diameter of 40 – 120 mesh or shot with a diameter of about 0.1 – 2.0 to the surface of the workpiece, so that the workpiece can achieve the same effect. The treatment effect will be different if the size of the shot is different. It is emphasized that shot blasting can also play a role in strengthening. Now the domestic equipment has entered a misunderstanding that only shot peening can achieve the purpose of strengthening. Enterprises in the United States and Japan use shot blasting for strengthening, and each has its own advantages. For example, for a workpiece such as a gear, the shot angle of shot peening cannot be changed, and the initial speed can only be changed by frequency conversion. However, it has large processing capacity and fast speed, while shot blasting is just the opposite. The effect of shot peening is not as good as that of shot blasting. What is sand blasting? Sand blasting is a method that uses compressed air to blow out quartz sand at high speed to clean the surface of parts. It is also called sand blowing in the factory. It can not only remove rust, but also remove oil. It is very useful for coating. Commonly used for rust removal on the surface of parts; Surface modification of parts (this is the purpose of small wet sand blasting machine sold in the market. The sand is usually corundum and the medium is water); In the steel structure, the application of high-strength bolts for connection is a more advanced method. Because the high-strength connection uses the friction between the joint surfaces to transfer the force, the quality requirements of the joint surface are very high. At this time, the joint surface must be treated by sand blasting. Sand blasting is used for complex shape, easy to remove rust by hand, low efficiency, poor site environment and uneven rust removal. General sandblasting machines have sandblasting guns of various specifications. As long as they are not a particularly small box, they can put the gun in and clean it. The supporting product of pressure vessel – head adopts sand blasting to remove the oxide scale on the workpiece surface. One kind of processing is to use water as a carrier to drive emery to process parts, which is a kind of sand blasting. Both shot peening and sand blasting can clean and decontaminate the workpiece. The purpose is to prepare for the next process, that is, to ensure the roughness requirements of the next process. In addition, in order to ensure the consistency of the surface, shot blasting can strengthen the workpiece, so sand blasting is not obvious. Generally, shot blasting is a small steel ball and sand blasting is quartz sand. According to different requirements, the mesh number. Sand blasting and shot peening are used in precision casting almost every day. Supplement: 1. Both shot peening and sand blasting are surface treatment, but it does not mean that only castings are shot peening. 2. The main function of sand blasting is to remove rust and oxide scale on the surface, such as parts after heat treatment, while shot peening has many functions and functions. It not only removes rust and surface oxide scale, but also improves surface roughness, removes machining burrs of parts, eliminates internal stress of parts, reduces deformation of parts after heat treatment, and improves wear resistance and pressure resistance of parts. 3. There are many processes for shot blasting, such as castings, forgings, parts surface after machining, parts surface after heat treatment, etc. 4. Sand blasting is mainly manual operation, while shot peening is more automatic and semi-automatic. Add again (some repetition, some conflict): 1. Shot and sand Shot is generally spherical particles without edges and corners, such as cast steel shot, steel wire grinding shot, etc; Sand refers to angular sand particles, such as cast steel sand, brown corundum, white corundum, river sand, etc. 2. Spraying and throwing Spraying is to use compressed air as power to spray sand or shot onto the material surface to achieve removal and certain roughness. Polishing is a method of impacting the material surface with centrifugal force generated when the shot rotates at high speed to achieve removal and certain roughness. Comparison of sandblasting, shot blasting and shot peening Difference between shot blasting and shot peening The sandblasting process shot blasting uses high-pressure air or compressed air as power, while shot peening generally uses a high-speed rotating flywheel to eject the steel sand at high speed. Shot peening has high efficiency, but there will be dead corners, while shot blasting is more flexible, but the power consumption is large. Although the two processes have different injection power and methods, they both aim at high-speed impact on workpieces, and their effects are basically the same. In comparison, shot blasting is relatively fine and easy to control accuracy, but its efficiency is not as high as shot peening. Shot peening is suitable for small workpieces with complex shapes. Shot peening is more economical and practical, easy to control efficiency and cost, and can control the particle size of pellets to control the injection effect, However, there will be dead corners, which is suitable for batch processing of workpieces with single shape and surface. The selection of the two processes mainly depends on the shape of the workpiece and the machining efficiency. Difference between shot blasting and sand blasting Both shot blasting and sand blasting use high-pressure air or compressed air as power to blow it out at high speed and impact the workpiece surface to achieve cleaning effect, but the effect is also different due to different media. Difference between sand blasting and shot blasting After sand blasting, the dirt on the workpiece surface is removed, the workpiece surface is slightly damaged, and the surface area is greatly increased, thus increasing the bonding strength between the workpiece and the coating/coating. The surface of the workpiece after sand blasting is of the natural color of metal, but because the surface is rough and the light is refracted, it has no metal luster and is a darkened surface. After shot blasting treatment, the dirt on the workpiece surface is removed, the workpiece surface is slightly damaged without damage, and the surface area is increased. Because the workpiece surface is not damaged in the machining process, the excess energy generated during machining will lead to the surface strengthening of the workpiece matrix. After sandblasting, the surface of the workpiece is also the natural color of metal. However, because the surface is a spherical surface, part of the light is refracted, so the workpiece is processed into matte effect. Difference between sand blasting and shot peening 1. The two are different in meaning: shot peening uses the high-speed rotating impeller to throw out small steel shot or small iron shot and impact the part surface at high speed, so the oxide layer on the part surface can be removed. Sand blasting is the process of cleaning and roughening the substrate surface by using the impact of high-speed sand flow. 2. Different in nature: shot peening uses the high-speed rotating impeller to throw out the abrasive; Sand blasting is the use of compressed air to blow out the abrasive at high speed. 3. The two are suitable: shot peening is often used to clean the casting surface or strengthen the part surface; After sand blasting, the dirt on the workpiece surface is removed, the workpiece surface is slightly damaged, and the surface area is greatly increased, thus increasing the bonding strength between the workpiece and the coating/coating. The steel plate working face of our daily car is strengthened with shot blasting, which can significantly improve the fatigue strength of the material. Shot peening uses a motor to drive the impeller body to rotate, relying on the action of centrifugal force; Shot peening is usually a high-speed rotating flywheel that ejects steel sand at high speed. Source: China Pipe Fittings Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Pipeline pressure test is the last process of pipeline construction engineering. It is not only a comprehensive inspection of pipeline construction quality, material performance and pipeline integrity, but also an inspection and guarantee of whether the pipeline system can operate safely without fault under the design operating pressure. Therefore, great attention should be paid to the pressure test. The purpose of the pressure test of the main pipeline is to eliminate the hidden dangers and defects of the pipeline, obtain a greater degree of safety and ensure the safety of the pipeline in operation. There are generally two types of pressure test methods for long-distance pipeline: air pressure and water pressure. Water pressure can be pided into fresh water pressure test and sea water pressure test due to different pressure test media. Using water as pressure test medium has the following advantages: low cost; Although water is compressible in theory, the effect of compression on hydrostatic test can be ignored; Water is not toxic; Water is not flammable; The emission problem is also small; The pressure of water on the pipe wall is uniform; When the pipeline breaks, the water pressure will be released quickly, which can reduce the damage to the environment; For most areas, water intake is also more convenient, and has been increasingly used as a main means of pressure test of long-distance pipeline. Pressure test process of pipeline The pipeline pressure test process mainly includes: water injection in the pipe, strength pressure test, tightness pressure test, pressure relief and drainage. The above processes are introduced below. Pressure test steps: fill water and check whether the air in the exhaust pipe is drained; Conduct strength test after boosting; Conduct tightness test for pressure stabilization; Pressure relief for a period of time; Drain water after passing the hydrostatic test; If the natural gas pipeline is subject to hydrostatic test, it shall be dried after drainage. Before water supply for pipeline hydrostatic test, the water quality of water source shall be tested and analyzed to confirm that the water for pressure test is clean and the PH value is neutral, which has no harmful impact on the pipeline. The cleanliness of the pipeline has a great impact on the pre commissioning, construction and operation of the pipeline. If there is a large amount of sediment deposition after the pressure test of the pipeline, it will increase the water pushing pressure, and seriously cause the phenomenon of ball passing and pipe blocking. It is very difficult and dangerous to deal with, especially if there are a large number of dust particles during the operation of the gas pipeline, it will cause damage to pipe fittings and valves, And different substances in the water will affect the corrosion of the pipeline: After the pipeline is filled with water, start the pressure test pump to boost the pressure and conduct the strength pressure test of the pipeline. As long as the pressure at one end of the pipe section reaches the predetermined pressure, the pressure rise will be stopped. The strength test pressure in China is 1.25 times of the operating pressure, and the operating pressure shall be implemented in accordance with the relevant provisions in China’s specifications. If the strength is stabilized for 4 hours and the pressure drop is not greater than 1%, it is qualified. The tightness pressure test shall be conducted after the strength stabilization is qualified. During the tightness test, slowly open the relief valve to reduce the pressure to the test pressure value. The same as the strength pressure test, the pressure relief shall be stopped as long as the pressure at one end of the pipe section reaches the predetermined pressure. The tightness test is qualified if the pressure is stabilized for 24 hours and the pressure drop is less than 1%. After the pressure test is completed, the pressure of the pipeline shall be removed through the pressure relief valve, and the water in the pipeline shall be discharged by using the original water feeding pig in the pipeline and the air compressor. During drainage, the water can be discharged outside the pipeline, or the water can be discharged to the next pipeline as the water supply source of the next pipeline. This not only saves time and labor, but also saves limited water resources. Source: China Chemical Pipelines Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Installation process and complete construction operation process of natural gas pipeline The installation and construction of natural gas pipeline includes three steps: pipeline welding, pipeline anti-corrosion and pipeline pressure test. Survey site According to the design and construction technical disclosure, the site survey shall be carried out jointly with the owner, supervision engineer and other relevant personnel. Preparation before construction 1. Organize all construction personnel to conduct detailed investigation on other pipelines within the site and draw detailed construction sketches to ensure construction safety. 2. Check the performance indexes of the pipes used. 3. Cooperate with the on-site construction team, including pipe welding, pressurization and air tightness test. 4. The placement of equipment shall be considered from many aspects, that is, to facilitate construction and minimize the impact on the surrounding environment. Surveying and setting out According to the comparison between the design drawings and the site, accurately measure, point and mark the design pipeline position, and find and eliminate the obstacles that may affect the construction as early as possible. Steel pipe derusting, anti-corrosion and painting 1. Before steel pipe welding, the oxide layer and dirt on the inner and outer pipe walls shall be removed. The derusting shall be carried out by electric polishing machine. The derusted pipes shall be painted with primer in time to prevent secondary oxidation. 2. The steel pipe adopts ordinary anti-corrosion, primer → finish coat → finish coat. Before anti-corrosion and painting of the steel pipe, the dirt such as rust, welding slag, burr, oil and water on the coated surface shall be removed. The coating shall be complete and uniform, the color shall be consistent, and there shall be no damage and flow; The coating film shall be firmly attached and the color shall be consistent. Pipe welding Steel pipe welding process requirements 1. The steel pipe should be cut by mechanical method. If it is cut by oxygen or acetylene flame, the size must be correct, the surface must be flat, and the notch shall be free of crack, double skin, burr, oxide, etc. Mechanical method should be adopted for groove processing to polish the uneven parts. 2. For pipe connection, it is not allowed to eliminate the gap, deviation, staggered joint and non concentricity of the pipe section by means of strong matching or heating the pipe. During alignment, the balance shall be measured 200mm away from the grounding center, and the allowable deviation is 2mm. 3. The inclination deviation of the cut end face shall not be greater than 1% of the outer diameter of the pipe and shall not exceed 3mm. 4. Pipe welding process: (1) Material requirements: the material and specification must meet the design requirements, with factory certificate and retest report. (2) Welding rod requirements: the coating shall be free of cracks, pores and other defects. During welding, the arc shall burn stably, melt evenly, and there shall be no blocking and falling off. It shall be dried for use. (3) Preparation before welding: the pipe orifice shall be cleaned, the inner wall shall be flush, the misalignment shall not be greater than 1mm, the welded junction device shall be firm, and necessary measures shall be taken to prevent stress deformation during welding. (4) Welding equipment: AC welding machine, DC welding machine, angle grinder, drying box and insulation barrel. (5) Welder requirements: Welders must hold welding certificates and undergo pre job training and assessment. Safety protection shall be provided at the operation site to prevent burns, electric shock and collapse. (6) Welding process: rust shall be removed before welding, and antirust paint shall be applied after exposing the natural color of the metal. During pipeline welding, reasonable welding methods and sequences shall be adopted to ensure the quality of arc starting and arc ending. Multi layer welded joints shall be staggered, and slag and spatter shall be removed after each layer is welded. If there is any defect, angular grinder shall be used to eliminate and re weld. Single side manual arc welding shall be used for welding, and after each welding is completed The first layer shall be polished with hand grinding wheel before welding the next layer. In order to reduce welding deformation and welding stress, symmetrical or segmented welding methods can be adopted. The welds shall be visually inspected. The weld reinforcement height shall be 1mm and the weld width shall cover the groove by 2mm. The weld surface shall be free of cracks: seams, pores and slag inclusion. The welds shall meet the 100% qualification of grade II films. (7) Welding parameters:Pipe wall thickness (mm)Number of welding layersDiameter of electrodeWelding current (A)3.5-823.2105-120Name of the connectorPipe wall thickness (mm)Blunt edgeGroove angleHi-LoV-groove3-3.50-330º1 (8) Welding inspection: The surface quality of welds for visual inspection shall comply with class II I weld standard (GB50236-98), and the internal quality shall comply with class III weld standard (GB50236-98). The number of NDT for welds in general sections shall not be less than 20% of the total number of welds. (9) For manual arc welding, the wind speed shall not exceed 8m / s, and the number of times of repairing the same part of the unqualified weld shall not exceed 2. During welding, a reasonable welding sequence shall be adopted, and the interlayer joints of multi-layer welding shall be staggered. Pipeline excavation 1. The line shall be clearly marked on the road according to the drawing size and relevant regulations, and all sign lines must be double lines. 2. Mechanical trenching and manual trenching shall be used for earth excavation. Manual and careful operation shall be carried out at the location where the site is narrow or there are underground pipelines. 3. The earthwork is located in the south of the trench, and the operation site is located in the north of the trench. 4. The straight pipe trench shall be straight and smooth, and the curved pipe trench shall be smooth and excessive without concave convex and broken lines. The ditch wall and bottom shall be flat, and there shall be no collapse and sundries in the ditch. 5. When excavating the pipe trench, it is necessary to prevent rainwater from scouring the pipe trench. The excavation of each section of pipe trench shall be closely combined with pipeline assembly and welding and trench backfilling, and one section of excavation shall be completed in combination with medium and short-term weather forecast. 6. In the process of slotting, humus and residue need to be discarded, and the excess earthwork should be temporarily stored in a temporary storage yard near the site. Electrofusion connection 1. Cut off the pipe with special tools, keep the end face of the pipe perpendicular to the pipe axis, scrape off its skin, scrape off half the length of the electric melting sleeve, and wipe the dirt on the connecting surface of the pipe and pipe fittings with clean cotton cloth 2. Draw a positioning line according to the insertion depth of the pipe, so as to ensure that the pipe can be equally inserted into the electric melting sleeve during assembly 3. Insert the pipe into the socket at one end of the electric melting sleeve to the positioning line, and check whether the inlet and outlet parts meet the requirements. 4. Install the sleeved pipe and electrofusion sleeve on the interface fixture and fix it with the fixture; 5. Fix the pipe at the other end on the fixture, push the fixture along the sliding shaft to insert it into the socket at the other end of the electric melting sleeve, and keep the two connecting pipes on the same axis. 6. Connect the wire plug of the controller with the electric fusion sleeve socket, correctly set the welding voltage, current, welding time and other parameters, open the electric fusion button of the controller, conduct electric fusion, and the welding time enters the countdown. 7. After the dissolution is completed, cool it to the ambient temperature according to the specified cooling time, and remove the fixture and electrofusion wire. Pipe laying 1. Before the pipeline is laid into the trench, the trench bottom shall be measured to remove sundries, large soil blocks and ponding in the trench. 2. Special slings must be used for lowering the pipeline into the trench. It is strictly prohibited to damage the external anti-corrosion coating of the pipeline. It is strictly prohibited to lift the pipeline sharply or tighten the pipeline, resulting in bending or permanent bending. The spacing between lifting pipes is less than 20m. 3. After the pipeline is lowered to the groove bottom, it shall be close to the groove bottom and properly placed without external force. If there is any suspended part, it must be filled up. Pipe backfilling 1. After the installation inspection of the main body of the pipeline is qualified, the trench shall be backfilled in time, but the installation interface that has not been inspected shall be reserved. Before backfilling, the sundries left at the bottom of the trench must be removed. 2. Garbage, wood and soft materials shall not be used for backfilling. The backfill on both sides of the pipeline and within 0.5m above the pipe top shall not contain debris such as gravel and bricks, and shall not be backfilled with lime soil. The stones in the backfill soil above 0.5m from the pipe top shall not be more than 10%, the diameter shall not be more than 0.1M, and shall be evenly distributed. 3. During trench backfilling, the partially suspended part of the pipe bottom shall be backfilled first, and then both sides of the pipe shall be backfilled. 4. The backfill soil shall be compacted in layers. The virtual paving thickness of each layer is 0.2-0.3m. The backfill soil on both sides of the pipeline and within 0.5m above the pipe top must be compacted manually. The backfill soil above 0.5m above the pipe top can be compacted by small machinery. The virtual paving thickness of each layer should be 0.25-0.4m. 5. After backfilling and compaction on both sides of the pipe and 0.5m above the pipe top, the support of the trench shall be removed under the condition of ensuring safety, and the gap shall be filled with fine sand. 6. After the backfill is compacted, the compactness shall be checked in layers, and the backfill records shall be made. Pipe installation 1. Before the installation of pipes, pipe fittings and valves, the model, specification and material shall be checked in detail to see whether they meet the design requirements, and the manufacturer’s product factory certificate and other quality assurance data shall be provided. 2. Before the installation of valves, the shell strength and tightness test shall be carried out one by one. The strength test pressure shall be the nominal pressure of the valve [1.5 times of the nominal pressure of the valve, the test medium shall be water, the pressure shall be maintained for 5 minutes, the test J shall be water, the pressure shall be maintained for 10 minutes, and the valve disc sealing surface shall be qualified if there is no leakage. 3. During pipe alignment, the flatness shall be checked and measured 200mm away from the interface center, and the allowable deviation shall not be greater than 1mm. Pay attention to the radian in the overall layout of the pipe group. 4. The pipe assembly clearance shall not be greater than 2mm, and the misalignment of the outer wall shall not be greater than 3mm, otherwise it shall be thinned and corrected. 5. During pipe connection, it is not allowed to use strong butt joint, or heat the pipe, add offset pad and other methods to eliminate the defects such as gap, deviation, staggered joint or non concentricity at the end face of the interface. 6. The flange connection shall be coaxial, the center deviation of the bolt hole shall not exceed 5% of the outer diameter of the hole, and the bolt shall penetrate freely, and the flange end face shall be parallel, the deviation shall not be greater than 1.5 ‰ of the outer diameter of the flange, and shall not be greater than 2mm, and the skew shall not be eliminated by tightening the bolt. All bolts shall be grade 8.8 strength bolts. 7. During installation, the safety distance between the gas pipeline and other adjacent pipelines and structures shall be strictly controlled, and the operation shall be carried out according to relevant operating procedures. The buried slope and depth must meet the design requirements. 8. For construction every other day, cast iron pipe shall be used to block the pipe orifice temporarily to prevent sewage, sundries and animals from entering the pipe. 9. The pipeline installation shall be inspected every 6-10m according to the inspection contents, and the next process can be carried out only after it is qualified. Install the retaining bracket 1. During pipeline installation, the support shall be fixed and adjusted in time, the position of the support shall be accurate, the installation shall be flat and firm, and the contact with the pipeline shall be close. 2. The specification, type and installation position of the adopted support shall meet the design requirements, and the deviation of elevation and coordinate shall not exceed 10mm (there shall be no positive deviation of elevation). 3. The sliding surface of the guide support or sliding support shall be smooth and flat without jamming. The guide plate shall not affect the sliding of the pipe support. The fixed support shall be fixed firmly. The height of the vertical plate of the pipe support shall meet the requirements of the insulation thickness. 4. The support weld shall be fully welded. When welding with the pipe, the pipe wall shall be free of defects such as biting and burning through, and the welding shall be completed before the pipe system test. 5. After the installation of pipe support, check whether the specification, type, installation position, weld and bolt fastening meet the requirements of drawing design and construction specifications one by one, whether there is missing installation and whether they are in close contact with the pipe. 6. The overhead of low-pressure gas pipeline can be laid along the outer wall of buildings with fire resistance rating not lower than grade II. 7. The clear distance between the gas pipeline along the outer wall of the building and the door and window openings of the building: the low-pressure pipeline shall not be less than 0.3m. Installation of valves and accessories 1. Check the packing before valve installation, and the gland bolt must have sufficient adjustment allowance. 2. Valves with flange or threaded connection shall be installed in the closed state. 3. Before installing the valve, the model shall be checked according to the design, and the installation direction shall be determined according to the gas flow direction. 4. The valve stem of the valve on the horizontal pipeline shall generally be installed within the upper half circumference. 5. When installing cast iron valves, avoid damage caused by strong connection or uneven stress. 6. The installation position of the valve shall not hinder the disassembly and maintenance of the equipment, pipeline and valve itself. The installation height of the valve shall be convenient for operation and maintenance. Generally, it is appropriate to be 1.2m away from the ground. When the valve is more than 1.8m away from the floor, it shall be centrally arranged and a fixed platform shall be set. 7. For valves on side-by-side pipelines, the clear distance between hand wheels shall not be less than 100mm. In order to reduce the pipeline spacing, valves arranged side-by-side shall be staggered. 8. The operating mechanism and transmission device of the valve shall be adjusted as necessary to make the action flexible and accurate. Indoor pipeline installation 1. First install the pipe support according to the drawing and the actual situation, then install the processed pipe, and fix it after appropriate adjustment. If the floor has reserved the casing, install it according to the reserved position. If not reserved, the casing shall be added. 2. In order to ensure the installation quality, the riser installation shall be measured and installed with pendant and level. 3. The installation of buried pipeline at the entrance shall be constructed according to the slope requirements of the drawing of 0.02%, and polyethylene shall be strengthened for anti-corrosion treatment according to the requirements of the drawing. 4. There shall be no welded junction in the pipe passing through the floor casing. 5. The finished pipe orifice shall be bound with plastic cloth to prevent foreign matters from entering. 6. The straightness of horizontal pipeline for pipeline installation shall be 2L / 1000 and 3L / 1000 of riser. 7. The horizontal clear distance from indoor water supply, drainage and heating pipes shall not be less than 100mm, and the cross clear distance shall not be less than 10mm. Gas meter installation 1. The gas meter must meet the following conditions before installation. 2. The gas meter has factory certificate, the manufacturer has production license, and the meter has been tested by legal testing unit; 3. It shall not exceed 4 months from the date of delivery. If it exceeds, it shall be tested by the legal testing unit; 4. No obvious damage. During the installation of gas meter, collision, inversion and knocking are not allowed, and rust, sundries and oil stain are not allowed to fall into the instrument. 5. The diaphragm meter must be installed flatly, and the lower part shall be supported. The horizontal clear distance between the gas meter and the surrounding facilities is listed in the following table. Installation of surge tank 1. It shall be stated on the certificate of the pressure regulating box that it meets the requirements of the quality standard through the air pressure test, strength and tightness, as well as the adjustment of inlet and outlet pressure. Do not install without the above instructions. 2. When installing the surge tank, it shall meet the following requirements: 3. Before installation, check that the outer surface of the surge tank is free of defects such as sand sticking, sand holes and cracks; 4. The installation of the surge tank shall be flat and stable, and the inlet and outlet directions shall not be wrong; 5. The connecting pipe of the membrane of the surge tank and the connecting pipe of the commander shall be connected above the outlet pipe of the surge tank, and the length of the connecting pipe shall meet the actual requirements. Overhead pipeline installation 1. The construction personnel shall be skilled and have high-altitude operation experience. 2. The lifting machinery used by the personnel shall be an electric basket (the disassembly and assembly of the basket must be operated by licensed professionals), and the lifting of pipes shall be a 2-ton electric crane. Walkie talkies shall be equipped on site to ensure clear signals and close cooperation among the commanders, overhead construction personnel, lifting machinery operators and ground assistance personnel. 3. Safety rope shall be set along the overhead construction pipeline. The safety rope shall be bound firmly and independently, and shall not be bound on the lifting machinery and basket support. A falling self-locking device is set on the safety rope. Overhead construction personnel shall wear safety helmets and safety belts. The connection between the safety belt and the self-locking device shall be reliable and firm. 4. Before the installation of the pipe support, the measurement shall be carried out to ensure the correct position of the support. The support installation must be flat and firm and in good contact with the pipe. 5. The overhead pipeline shall be prefabricated and derusted on the ground, and the first layer of yellow marking ready mixed paint shall be painted. 6. The prefabricated pipeline shall be hoisted to the installation position with hoisting machinery, fixed by personnel in a basket, and painted with the second layer of yellow marking ready mixed paint. Construction of supporting facilities 1. Valve installation When installing indoor steel valves, select corresponding connecting accessories according to the material of the pipeline, and be equipped with steel flanges, gaskets, bolts and other accessories of the same diameter. The flange surface and the valve flange shall be concentric and parallel, and the parallel deviation shall be 1.5% of the outer diameter of the flange and ≯ 2mm. 2. The specifications, dimensions and accuracy of bolts and nuts used in the project shall meet the requirements of drawings and GB97-81. The threads shall be complete, free of scars, thorns and other defects, and the bolts and nuts shall be well matched without looseness, jamming and other phenomena. 3. The installation position of the valve shall avoid the areas with dense and complex underground pipe network or heavy traffic as far as possible, and choose the place convenient for daily maintenance. Pipeline purging Pipeline purging is the same as general pipeline purging. Blasting purging can be carried out in sections. The medium is compressed air, and the pressure shall not exceed the working pressure of the pipeline. Strength test After removing the air in the pipeline, start the strength pressure test. The medium pressure gauge pressure is 0.6MPa and the low pressure is 0.2MPa. There is no pressure drop after stabilizing for 1h, and the inspection result is qualified. Air tightness test In the air tightness test, the medium pressure is 0.46mpa and the low pressure is 0.1MPa. It shall be maintained for a certain time to make the temperature of the test medium in the pipeline consistent with the ambient temperature of the pipeline. After the temperature and pressure are stable, the timing shall be started. The air tightness test shall be stabilized for 24 hours. If there is no obvious leakage or pressure drop, it will be qualified. Handover acceptance 1. After the completion of all construction of the project, the handover acceptance shall be carried out, and the owner, the supervision unit and other relevant departments shall be notified to attend the handover. 2. The acceptance items mainly include strength, air tightness test, valve well and other aboveground facilities, which can be passed only after confirmation and signature. 3. The project acceptance shall be formally completed after the owner’s acceptance team and other departments issue the acceptance certificate. 4. For the delivery of completion data, the completion data shall include all contents in the completion data specified by the owner, and the owner shall issue the handover certificate of completion data.

The long weld neck flange of pressure vessel is optimized through two specific examples, and the effects of cone neck height and flange thickness on the three main stresses of flange axial stress, radial stress and tangential stress are analyzed. The calculation results show that when the flange thickness and cone neck height are adjusted to be similar, the three main stress values are close to the full stress value. This optimized design makes the flange compact in structure, reasonable in force, reduces the weight, and can significantly reduce the flange cost. For long weld neck flanges with small diameter and low pressure, on the premise of ensuring that the slope of flange cone neck section is less than 1:3, the flange can not have straight edge section. Optimal design of long weld neck flange Long weld neck flange is the most commonly used equipment flange in pressure vessels. Although NB/T 47023-2012 standard [7] gives the long weld neck flange of carbon steel and low alloy steel pressure vessels with nominal pressure of 0.6 ~ 6.4MPa and working temperature of – 70 ° C ~ 450 ° C, the flange, stud, nut and backing sheet materials need to be fully implemented according to the matching table and correction table in the standard, which is subject to many restrictions, Moreover, in engineering practice, many long weld neck flanges are beyond the scope of NB/T 47023-2012 standard, such as stainless steel flange or long weld neck flange with working temperature exceeding 450C, which shall be in accordance with GB/T 150 3-2011 design and calculation of non-standard flange. Through two specific calculation examples, the author optimizes the design of UNS S30408 long weld neck flange and 15crmo long weld neck flange, analyzes the effects of cone neck height and flange thickness on the three main stresses of flange axial stress, radial stress and tangential stress, and gives suggestions on the optimal design of long weld neck flange, which can be used as a reference for relevant designers of pressure vessels. In addition, the author also draws lessons from the flange design schemes of some large design institutes and engineering coMPanies. For the long weld neck flange with small diameter and low pressure, it is recommended that the flange design should not have straight edge section, but according to GB/T 150 3-2011 it is required to ensure that the slope of flange cone neck section is 31:3, which can significantly reduce the flange cost. The flange material of a vessel is s30408 and the design temperature is 300C; Design pressure: 2.6MPa; The specification of butt barrel is dn1000x14mm, and the winding pad is selected: M = 3.0, y = 69MPa; The allowable stress of flange under normal temperature [0] = 137MPa, the allowable stress of flange under design temperature [0] / = 85MPa, the material of stud is 35CrMoA, the specification is M30, the quantity is 48, and the corrosion allowance is not considered. Firstly, the author designs and calculates with reference to the overall dimensions of NB/T 47023-2012 standard equipment flange. The outer diameter of the flange is 1215mm, the inner diameter of the flange is $1000mm, the diameter of the bolt circle is 1155mm, the effective thickness of the flange is 100mm, the height of the cone neck is h = 42mm, the effective thickness of the large end of the neck is G1 = 36mm, and the effective thickness of the small end of the neck is G0, which is taken as the thickness of the butt cylinder 14mm. After preliminary calculation, the axial stress 0h = 199.25MPa > 1.5 [called /, comprehensive stress max (0.5 (0h + 0r), 0.5 (0h + 0t)) = 136.01MPa > [0h] /, and the flange strength is unqualified. At this time, some designers will blindly increase the flange thickness until it is qualified, which is not desirable. Blindly thickening the flange will cause material waste and unreasonable stress on the flange. When the axial stress is too large or too small, the method of adjusting the size of the cone neck shall be adopted, and the thickness or height of the cone neck can be adjusted. The maximum value of the axial stress is usually located on the section of the small end of the cone neck, which can be judged from the coefficient F. the coefficient f is the stress at the small end of the cone neck. When f is greater than 1, the maximum stress is at the small end of the cone neck. When f is less than or equal to 1, the maximum stress is at the large end of the cone neck. In this example, in order to facilitate docking with the cylinder, the thickness of the small end of the cone neck is taken as the thickness of the cylinder without adjustment; the effective thickness of the large end of the cone neck shall be in accordance with the provisions of the minimum value of La in table.1 in GB/T 150.3. Table.1Cone neck heighth/ mmAxial stress is calculated/MPaAllowable axial stress value/MPaRadial stress is calculated/MPaAllowable radial stress value/MPaThe tangential stress is calculated/MPaAllowable tangential stress value/MPaComprehensive stress calculation value/MPaCombined allowable stress value/MPaCheck the results55167.82127.518.298564.8585116.3485Unqualified65143.75127.519.278559.7185101.7385Unqualified75120.8127.520.118555.348588.0785Unqualified78114.22127.520.348554.168584.1985Qualified It can be seen from the stress calculation results in Table.1 that after increasing the cone neck height, the axial stress value decreases significantly, the tangential stress value also decreases, and the radial stress value increases slightly. When the cone neck height increases to 78mm, the flange is checked and qualified, but is this the optimal design? In the above calculation process, the author only increases the cone neck height, and the flange thickness is not adjusted. The flange design should follow According to the full stress design principle, the axial stress and radial stress in the above calculation are close to the full stress value. Through further adjustment and calculation of the flange thickness and cone neck height, the author concludes that when the flange thickness is 90mm and the cone neck height is 84mm, the axial stress 0h = 116.04MPa, the tangential stress 0t = 52.25MPa, the axial stress and tangential stress value and the flange thickness are 100mm and the cone neck height is 78m M is basically the same, the radial stress 0r = 27.92MPa, and the radial stress value increases slightly. The flange thickness is reduced, the flange weight is significantly reduced, the flange cost can be significantly reduced, and the stress is reasonable. In the process of pressure vessel design and verification of several projects, the author found that some large design institutes and engineering coMPanies do not have straight edge segments in flange design, especially for long weld neck flanges with small diameter and low pressure. According to the provisions of GB/T 150.3 and JB4732 standards, long weld neck flanges can not have straight edge segments on the premise of ensuring the slope of flange cone neck section of 2:3, which is difficult to calculate The effective thickness of the small end of the flange neck is the thickness of the butt cylinder. The author also understands that the main purpose of the design institute’s design is to save flange materials, which is particularly important for the pressure vessel manufacturer. If the flange structure can be optimized, the flange cost can be significantly reduced. Moreover, in the actual production and manufacturing process, the groove type of the flange is often determined by the welding process , if there is no straight edge section, the thickness of the small end of the flange neck can be the same as that of the butt cylinder. In this way, whether the outer slope or the inner groove is adopted, it can ensure the inner flush during assembly, which is conducive to welding and does not need thinning treatment, which greatly improves the production efficiency. Flange optimization design is a complex and tedious process, and different designers often have different calculation results, but flange design must follow the principle of full stress, and give full play to the strength performance of flange materials through full stress optimization design. Through the above two examples, the author analyzes the three main stress values of flange, and adjusts the cone neck size and flange thickness respectively The design results that each stress value is close to the full stress are obtained. This optimal design makes the flange coMPact, reasonable stress and light weight. Therefore, the optimal design of the flange has obvious economic benefits. Source: China Stainless Steel Flanges Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Flange is the main connecting equipment of process pipeline in petrochemical enterprises. It has a large number and plays a very important role in production and operation. Most of Fujian coastal petrochemical enterprises are located in coastal areas. The high salt and high humidity marine corrosive atmosphere accelerates the corrosion rate of station flanges, resulting in a wide range of flange corrosion, especially flange clearance and flange gasket corrosion, which will not only cause equipment damage and shorten service life, but also cause management medium leakage, and bring great potential safety hazards to production safety. Flange corrosion mechanism By analyzing the mechanism of flange corrosion, there are mainly the following: The flange clearance space is narrow (the common flange clearance size is about 2 ~ 20mm, which is easy to accumulate dust and salt in the air, which are the inducing factors of corrosion and will lead to rapid corrosion; The flange has a gap structure, which is a typical structure of crevice corrosion and a prerequisite for the formation of crevice corrosion. A narrow flange gap will cause different oxygen concentrations inside and outside the gap, forming an oxygen concentration difference battery, greatly accelerating the occurrence of corrosion; Some petrochemical enterprises are located in coastal areas. The coastal air is high in humidity and salt. The water, gas and salt rich in the air are very easy to damage the flange coating and cause local corrosion; In the design stage, attention is not paid to the anti-corrosion part or anti-corrosion structure design, resulting in the connection of flange surfaces of different materials and the selection of metal gaskets with different materials from the flange surface during construction, resulting in galvanic corrosion. Flange anti-corrosion method The most appropriate anti-corrosion process shall be selected according to the corrosion environment and corrosion severity of the flange. The details are as follows: The anti-corrosion design avoids the design of narrow gap structure, resulting in gap corrosion and impurity accumulation, and the same metal is designed for the same flange surface to avoid galvanic corrosion; Strengthen the construction quality control during construction and strictly control the substrate bottom; Treatment and coating construction quality; Consider using non-metallic gaskets to reduce the probability of galvanic corrosion of gaskets. If sacrificial anode protection is provided, consider flange bridging; The new coating anti-corrosion process is adopted, and the coating material with excellent anti-corrosion performance is selected to completely fill and cover the flange gap, isolate the corrosion sources such as water, air and impurities, and contact the inner surface and gasket of the flange gap, so as to realize long-term anti-corrosion. The flange is coated with anti-corrosion materials In the case that the traditional coating anti-corrosion can not effectively prevent the flange from corrosion, through investigation, a variety of new coating materials are selected and tested on the flange, and their anti-corrosion processes are tested and improved. Some flange coating anti-corrosion processes have achieved good anti-corrosion effects. Wax magnetic anti-corrosion material is an excellent anti-corrosion protection material. Wax Tape anti-corrosion material mainly includes wax tape and wax magnetic primer, which can well isolate water and air. It can be applied to the anti-corrosion of various irregular pipelines, valves, flanges, bolts and other equipment in various corrosive environments. In 2006, NACE formulated the standards related to wax magnetic anti-corrosion materials. Viscoelastic anti-corrosion material is a new type of high molecular polymer anti-corrosion material originated in the Netherlands. Its state is between liquid and solid. At room temperature, it can remain in a state of no flow and no solidification for a long time. In addition, viscoelastic has very good bonding performance, waterproof and air isolation performance. According to the experience of equipment anti-corrosion maintenance in many petrochemical enterprises along the coast of Fujian, the traditional coating anti-corrosion can not meet the increasingly severe demand for station flange anti-corrosion. According to the characteristics of coastal and long-term marine corrosive atmosphere with high humidity and high salt, the disadvantages of the traditional coating anti-corrosion method are analyzed, and two coating anti-corrosion materials with excellent anti-corrosion performance are selected to be used in Fujian After several years of experience accumulation, it is considered that the wax magnetic anti-corrosion material and viscoelastic anti-corrosion material have good applicability and good anti-corrosion effect on the process flange equipment of petrochemical enterprises. Several solutions to flange corrosion The integrity of the flange connection is very important for the fluid piping system. Since the sealing surface of the flange connection can only be visually inspected when the whole system is closed, the inspection process should be as simple as possible. First, external corrosion should be eliminated. If it cannot be stopped, only ultrasonic technology can be used for detection. If external corrosion cannot be controlled, the process will be more complex and cannot be controlled Therefore, in order to monitor the whole system and provide effective and feasible quality control and maintenance procedures, the external corrosion protection of flanges and fasteners is very important. The ideal solution should take into account excellent corrosion resistance and simple construction procedures. It is suitable for flanges of various sizes and shapes. It is easy to operate bolts during maintenance. At present, the following solutions are commonly used in the market. 1. Maintenance paint solution Maintenance paint is a hard film that can be directly bonded to the substrate, usually epoxy or polyurethane paint. The flange has many corners and edges. Due to the effect of edge thinning, it is difficult for the traditional coating system to effectively cover the edge. Although the thickened coating can solve the problem of edge protection, it will seal the fasteners and cannot be removed for future maintenance. 2. Mechanical solutions The gap between flange and flange surface is mainly sealed by protective cover, usually made of stainless steel or plastic clamp, and equipped with rubber sealing strip. This protection method is not flexible, and it is necessary to store covers or fixing devices that fully match flanges of various sizes. 3. Tape or semi-solid anti-corrosion tape solution Roll packaged tape (such as Vaseline tape, wax tape or elastic polymer bandage) is protected by winding on the surface of the substrate. Since the semi-solid polymer is waterproof, this protection method can provide reliable protection. However, if the flange shape is complex, this material is not only time-consuming, but also difficult to construct. 4. Hot melt plastic solutions Hot melt plastic is essentially a waxy fusible polymer heated at high temperature, which can be sprayed on the substrate surface through professional hot melt equipment. The advantage of this protection method is that it can be remelted and reused, saving cost. However, although it can be reused, it still needs hot work, professional equipment and construction services, but it is not easy to open and close during maintenance Seal. 5. Polymer sealed bag solution The sealing bag can completely cover the flange. Its composition is composed of low permeability polymer, corrosion inhibitor steam and desiccant. It is easy to install, but the two ends of the bag are only sealed with tape instead of long-term effective mechanical bonding. The steam space has a large area, it is easy to accumulate a large amount of water, and the corrosion inhibitor will be consumed over a period of time. Source: China Flanges Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

In flange joint sealing, when carbon steel flanges or stainless steel flanges are equipped with 304 material bolts, leakage problems often occur in operation. This lecture will make a qualitative analysis of this. What are the basic differences between 304, 304L, 316 and 316L materials? 304, 304L, 316 and 316L are commonly used stainless steel materials in flange joints (including flanges, sealing elements and fasteners). 304, 304L, 316 and 316L are stainless steel type codes of American material standard (ANSI or ASTM), belonging to 300 series class I steel of austenitic stainless steel. The brands corresponding to the domestic material standard (GB/T) are 06cr19ni10 (304), 022cr19ni10 (304L), 06cr17ni12mo2 (316), 022cr17ni12mo2 (316L). This kind of stainless steel is generally referred to as 18-8 stainless steel. Refer to table 1304, 304L, 316 and 316L. Due to different alloying elements and amounts, their physical, chemical and mechanical properties are also different. Compared with ordinary stainless steel, they have good corrosion resistance, heat resistance and processability. The corrosion resistance of 304L is similar to that of 304, but because the carbon content of 304L is lower than that of 304, it has stronger resistance to intergranular corrosion. 316 and 316L are molybdenum containing stainless steels. Due to the addition of molybdenum, their corrosion resistance and heat resistance are better than 304 and 304L. Similarly, because the carbon content of 316L is lower than that of 316, its crystal corrosion resistance is better. 304, 304L, 316 and 316L austenitic stainless steels have low mechanical strength. The room temperature yield strength of 304 is 205mpa and that of 304L is 170Mpa; The room temperature yield strength of 316 is 210mpa and 316L is 200MPa. Therefore, the bolts made of them belong to low strength bolts. Table.1 carbon content,% room temperature yield strength, MPa, recommended maximum service temperature, ℃ Why should bolts of materials such as 304 and 316 not be used for flange joints? As mentioned in the previous talks, the flange joint is separated from the sealing surfaces of the two flanges due to the internal pressure, resulting in the corresponding reduction of gasket stress. The other is the relaxation of bolt stress due to the creep relaxation of gasket or the creep of bolt itself at high temperature, which also reduces the gasket stress and leads to leakage failure of flange joint. In actual operation, bolt force relaxation is inevitable, and the bolt force of initial tightening will always drop with time. Especially for flange joints under high temperature and severe cycle conditions, after 10000 hours of operation, the bolt load loss often exceeds 50%, and attenuates with the extension of time and the increase of temperature. When the flange and bolt are made of different materials, especially when the flange is made of carbon steel and the bolt is made of stainless steel, the thermal expansion coefficient 2 of the bolt and flange materials is different, such as the thermal expansion coefficient of stainless steel at 50 ℃ (16.51 × 10-5/℃ specific carbon steel thermal expansion coefficient (11.12) × 10-5/℃ is large. After the device is heated up, when the expansion of the flange is less than that of the bolt, after the deformation is coordinated, the bolt elongation decreases, resulting in the relaxation of the bolt force, which may lead to the leakage of the flange joint. Therefore, when the high-temperature equipment flange and pipe flange joint, especially the thermal expansion coefficients of the flange and bolt materials are different, the thermal expansion system of the two materials shall be improved as much as possible The number is similar. It can be seen that the mechanical strength of austenitic stainless steels such as 304 and 316 is low, and the room temperature yield strength of 304 is only 205mpa and 316 is only 210Mpa. Therefore, in order to improve the anti relaxation and anti fatigue ability of bolts, measures to improve the installation bolt force are taken. For example, when the maximum installation bolt force is used, it will be mentioned in the subsequent forum that the installation bolt stress is required to reach 70% of the yield strength of bolt materials In this way, it is necessary to improve the strength grade of bolt materials and use high-strength or medium strength alloy steel bolt materials. It is obvious that except cast iron, non-metallic flange or rubber gasket, for semi-metallic and metal gaskets with high pressure grade flange or gasket stress, bolts with low strength materials such as 304 and 316 cannot meet the sealing requirements due to insufficient bolt force. What needs special attention here is that in the American stainless steel bolt material standard, 304 and 316 have two categories respectively, namely b8cl.1 and b8cl.2 of 304 and b8mcl.1 and b8mcl.2 of 316. Cl.1 is subject to carbide solution treatment, while CL.2 is subject to strain strengthening treatment in addition to solution treatment. Although there is no fundamental difference between b8cl.2 and b8cl.1 in terms of chemical corrosion resistance, the force relative to b8cl.1 and b8cl.2 For example, the yield strength of b8cl.2 bolt material with a diameter of 3/4 “is 550MPa, while the yield strength of b8cl.1 bolt material with all diameters is only 205mpa, which is more than twice the difference. 06cr19ni10 (304) and 06cr17ni12mo2 (316) in domestic bolt material standards are equivalent to b8cl.1 and b8mcl.1. [Note: GB/T150.3 pressure vessel part III design] The bolt material s30408 in is equivalent to b8cl.2; s31608 is equivalent to b8mcl.1. In view of the above reasons, GB/T150.3 and GB/T38343 technical regulations for installation of flange joints stipulate that the usual 304 (b8cl.1) and 316 (b8mcl.1) bolts are not recommended for pressure equipment flanges and pipe flange joints. Especially under high temperature and severe cycle conditions, they should be replaced with b8cl.2 (s30408) and b8mcl.2 to avoid low installation bolt force. It should be noted that when low-strength bolt materials such as 304 and 316 are used, even in the installation stage, because the torque is not controlled, the bolt may have exceeded the yield strength of the material and even fracture. Naturally, if there is leakage during the pressure test or start of operation, the bolt force cannot go up and prevent the leakage even if the bolts are tightened continuously. In addition, these bolts are disassembled It can not be reused after installation, because the bolt has been permanently deformed and the cross-section size of the bolt becomes smaller, it is easy to break when it is installed again.

With the development and progress of medium thick steel plate technology, people pay more attention to the product quality, and the production enterprises pay more attention to the requirements of product quality and energy saving. From the current development situation in the world, the heat treatment thick plate products in the treatment, Japan’s technology is the most advanced. Compared with the advanced technology in China and the world, there are many quality defects in production, which have a serious negative impact on the quality of medium thick steel plates, which leads to the repair and treatment in a large range in the operation, which greatly affects the whole production order, and also causes the steel plate to be scrapped due to the repair and grinding, resulting in a certain amount of economic loss of the enterprise and adverse impact on the development of the enterprise. 1. heat treatment process of medium thick steel plate With the improvement of social productivity, people have gradually improved the quality of steel. The mechanical properties of steel can be improved by adding a certain amount of alloy elements to the steel production process and then heat treatment. The heat treatment of medium thick steel plates is mainly in four aspects: normalizing, high temperature, tempering, spheroidization. 1.1 normalizing treatment Normalizing treatment is also called normalization treatment. The strength of medium thick steel plates is usually large, but the toughness is very low. Therefore, normalizing treatment should be carried out, and then placed in air for cooling. Thus, fine gold particles will exist after cooling, and high-tech plate materials can be obtained after normalization treatment. 1.2 high temperature treatment High temperature treatment is also called tempering treatment, the main function of this treatment is to remove the stress existing inside the steel plate. There is a significant difference between the treatment and the normalizing treatment, which requires that the temperature control is within AC3. 1.3 conditioning and quality control The quenching and tempering process is a combination of quenching and tempering. The requirements of this process for heat treatment are relatively high. Heat treatment furnace, low temperature tempering furnace and pressure quenching machine are the necessary equipment. Martensite structure can be formed in the production of medium thick steel plates. It can be heated and tempered at low temperature, which is the whole process of tempering treatment. 1.4 spheroidization treatment Spheroidization is to form spheroidized structure after heating treatment of medium thick steel plates. After the treatment, the plate can be used as tool steel plate, and its comprehensive performance is relatively high. In addition to the above mentioned heat treatment processes, in the specific production practice, technicians can optimize and integrate many aspects, and then form new heat treatment processes, such as the new normalizing cooling control process and the normalizing tempering new process. The former is to avoid the insufficient strength of steel plate after normalizing treatment. After the heat treatment of steel plate, the treatment with water-cooled equipment can realize cold control treatment, and can prevent the steel plate strength from falling. The heat treatment of boiler pressure vessel steel plate is the best by normalizing tempering heat treatment. While the normalizing tempering treatment technology can be used for CrMo steel plate. 2. defect analysis 2.1 shot press in When the roller brush of shot blasting machine enters the end of a cycle, it will lead to the existence of wear. In the treatment of smaller steel plate, the shot material will follow the steel plate directly out of the shot blasting machine body. If there is no effective cleaning treatment, the shot material of the sheet material will be pressed after the stacking of the steel plate. In addition, due to the lack of shot blasting machine design, shot material is easy to appear in the position between steel plate and roller table in the process of processing. Because of the effect of self weight, the steel plate presses the shot material into the lower part, and enters into the steel plate after several times of rolling. 2.2 indentation of bottom roller The formation of the defects of the bottom roller indentation is that the bottom rolling surface is nodular, and the larger thickness of the steel plate appears indentation due to the high temperature on the lower surface. Causes of the surface nodulation of the bottom roller: there is a certain amount of oxide iron on some positions of the roller surface, and the increasing of the charging quantity causes the increase of the oxide scale, and then the accumulation in this position. At the same time, there is high temperature oxidation reaction under the soft condition of hot melt, and the roll surface nodule will increase. Under quenching or normalizing conditions, the layer oxide skin bonded on the roller surface is rolled by steel plate, and the layer by layer increases, and the density increases. In this case, the surface of the steel plate with larger thickness appears indentation under the influence of high temperature. In addition, the defects of drum and deformation at the bottom of the furnace will also have the problem of nodule. Source of iron oxide: one is outside the production link, the other is the abnormal situation in the furnace. The oxide skin outside the production link is the unclean shot blasting and the residual of shot material, because the design of shot blasting machine is unreasonable, the mechanical cleaning is not complete, the surface of steel plate has shot material, and there is oxide skin on the steel plate itself. The reason for the formation of iron oxide sheet in furnace is that the internal environment of heat treatment is abnormal and the residual oxygen is too large. The reason for the abnormal environment in the furnace is the quality problem of radiation tube. It can be checked by shutdown to determine whether it is caused by this reason. The furnace heating is carried out after mixing gas and combustion supporting air. The combustion in the radiation tube is realized by radiation. The sealing effect of the whole furnace is good. Therefore, the existence of internal oxygen is that air enters the inside when the furnace door is open. Because the furnace is designed as positive pressure and the furnace door is opened, nitrogen is used for automatic cleaning, so the probability of air entering into the furnace door is low; after the radiation pipe is treated for a long time with high temperature, the quality problems of the ceramic inner pipe, or the problems such as breakage and fracture due to the long service time, are caused, The reason for the metal appearance to be broken due to the lack of uniformity of heating may be due to the quality problems of the metal appearance itself. The burning through situation occurs in the work, which leads to the combustion air entering the inside from the damaged part. 2.3 extrusion deformation of side The deformation of the side extrusion is mainly due to the defects of the drum deformation in the roller table at the bottom of the heat treatment furnace. In the high temperature production process, the lower part of the steel plate contacts the drum at the bottom of the furnace and its gravity action will produce extrusion deformation under the movement in the furnace. The reason for the formation of drum drum is that the temperature difference between bottom roller and steel plate exceeds the standard, and the thickness of bottom roller wall is very small and the strength is relatively low. It is deformed when it contacts the steel plate due to the high temperature. 3. control measures 3.1 control of shot material pressing In order to effectively prevent the residual shot material on the surface of steel plate after shot blasting and prevent the shot material entering the furnace, generally, the scraper structure should be set at the outlet position of the shot blasting machine. At this time, the blowing device can be added at the outlet position to better clean the surface shot material; The following two points should be taken for pressing the shot material on the lower surface. One is that adding scraper in the cleaning room can prevent the existence of shot material on the lower surface of the steel plate; the second is to set up a supporting ring device on the surface of the conveying roller in the cleaning room of the shot blasting machine, which can effectively reduce the contact area between the steel plate and the roller, and prevent the pellet from entering the furnace. The above-mentioned shot blasting machine transformation can effectively prevent the pressing of shot material, eliminate these problems, and realize that the steel plate with thickness less than 50mm will not have any problem of shot pressing; the pressing of steel plate with thickness of more than 50mm generally appears on both sides of the steel plate. After treatment, the probability of shot pressing is reduced to less than 1%, which can improve the quality of steel plate, The productivity of shot blasting is promoted and the economic benefit is obviously improved. 3.2 control of the indentation of furnace bottom roller Strengthen the quality management of shot blasting to ensure that there is no residual and pressing of shot material on the surface of steel plate. The shot blasting effect reaches Sa2.5. According to the requirements of production process, the furnace cleaning can be carried out. According to the influence of the surface weight and friction force of the steel plate, the oxide skin can be crushed, and then the oxide skin will be removed before entering the furnace, so as to ensure the steel plate quality is qualified, and the service life of the bottom roller can be prolonged, and the indentation of the bottom roller can be eliminated from the root. After the above treatment, the treatment practice analysis of the indentation of the bottom roller is carried out for a long time. Under the condition that the temperature in the production environment is controlled below 900 ℃, there is no bottom roller indentation. When the production temperature is above 900 ℃, and the thickness is more than 30mm, the indentation of the bottom roller will be found, and the depth has been reduced from 0.3 to 1.0mm to 0.1-0.3mm, and the decrease is obvious. After the above treatment, the workload of manual grinding can be effectively reduced, the work efficiency is improved, and the surface nodular defects of bottom roller can be eliminated completely, which has high quality requirements. 3.3 control of extrusion deformation at the side To make the temperature of furnace bottom roll reach the uniformity standard, one is to raise the roller speed properly. The longer the steel plate contacts the roller surface, the lower the temperature will be, the temperature difference will increase, which will lead to the appearance of drum. If the low speed operation time is longer, the problem of roller table bending deformation will appear, and the speed can be improved to lower the temperature better, thus avoiding the problem of drum drum. Second, increase the swing amplitude appropriately. When the bottom roller rotates for one week, it can be determined as the best swing amplitude. At this time, the contact between the roller and the steel plate can be more uniform, and the heating of the roller table will become more uniform. Through installing the furnace offset control device, in the production of high temperature steel plate, it should be classified according to the thickness and time: the plate with thickness no more than 100mm is normally installed in the furnace; the quenched (positive) fire plate with thickness greater than 100m shall be padded on one side of wood block when aligning, so that the steel plate will be offset 200-300mm to the side. Through the implementation of the control measures of offset charging, the working surface of the bottom roller can be used alternately, and the temperature difference on the bottom roller position can be reduced better, and the heating is more uniform, and then the problem of drum drum of bottom roller can be prevented and the whole production level can be promoted. After the above treatment measures, the quenching furnace produces 145 pieces of 2725t steel plates with thickness of 150 mm, and has been put into the furnace 335 times. After the production of steel plates in the enterprise, the quality level of the side is relatively high, and there is no defect of side extrusion deformation. 4. conclusion In conclusion, the causes of surface quality defects of medium thick steel plate heat treatment are analyzed, and necessary treatment measures are taken. After some time of test, it is found that the quality improvement of steel plate is obvious, such as the pressing rate of shot material is controlled below 1% for a long time, the depth of the bottom roller indentation is kept at 0.1-0.3mm, the manual grinding quantity is small, and the edge of steel plate has no extrusion deformation defects, The overall quality level is very high, which brings high economic benefits to the enterprise. Author: Yugang China Stainless Steel Plates Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com) Reference [1] Xujianxiang, wuyuwan. Analysis and solution of surface quality problems of shot blasting steel plate in heat treatment line of medium thick steel plate [j]. Internal combustion engine and accessories, 2019, (12): 45-47 [2] Dong Zhanbin, Wang Xuesong, Liu Xiaohui, et al. Simulation and application of heat treatment furnace washing test of medium thick steel plate based on BP neural network [j]. Rolling steel, 2015, (2): 65-68

With the development and progress of medium thick steel plate technology, people pay more attention to the product quality, and the production enterprises pay more attention to the requirements of product quality and energy saving. From the current development situation in the world, the heat treatment thick plate products in the treatment, Japan’s technology is the most advanced. Compared with the advanced technology in China and the world, there are many quality defects in production, which have a serious negative impact on the quality of medium thick steel plates, which leads to the repair and treatment in a large range in the operation, which greatly affects the whole production order, and also causes the steel plate to be scrapped due to the repair and grinding, resulting in a certain amount of economic loss of the enterprise and adverse impact on the development of the enterprise. 1. heat treatment process of medium thick steel plate With the improvement of social productivity, people have gradually improved the quality of steel. The mechanical properties of steel can be improved by adding a certain amount of alloy elements to the steel production process and then heat treatment. The heat treatment of medium thick steel plates is mainly in four aspects: normalizing, high temperature, tempering, spheroidization. 1.1 normalizing treatment Normalizing treatment is also called normalization treatment. The strength of medium thick steel plates is usually large, but the toughness is very low. Therefore, normalizing treatment should be carried out, and then placed in air for cooling. Thus, fine gold particles will exist after cooling, and high-tech plate materials can be obtained after normalization treatment. 1.2 high temperature treatment High temperature treatment is also called tempering treatment, the main function of this treatment is to remove the stress existing inside the steel plate. There is a significant difference between the treatment and the normalizing treatment, which requires that the temperature control is within AC3. 1.3 conditioning and quality control The quenching and tempering process is a combination of quenching and tempering. The requirements of this process for heat treatment are relatively high. Heat treatment furnace, low temperature tempering furnace and pressure quenching machine are the necessary equipment. Martensite structure can be formed in the production of medium thick steel plates. It can be heated and tempered at low temperature, which is the whole process of tempering treatment. 1.4 spheroidization treatment Spheroidization is to form spheroidized structure after heating treatment of medium thick steel plates. After the treatment, the plate can be used as tool steel plate, and its comprehensive performance is relatively high. In addition to the above mentioned heat treatment processes, in the specific production practice, technicians can optimize and integrate many aspects, and then form new heat treatment processes, such as the new normalizing cooling control process and the normalizing tempering new process. The former is to avoid the insufficient strength of steel plate after normalizing treatment. After the heat treatment of steel plate, the treatment with water-cooled equipment can realize cold control treatment, and can prevent the steel plate strength from falling. The heat treatment of boiler pressure vessel steel plate is the best by normalizing tempering heat treatment. While the normalizing tempering treatment technology can be used for CrMo steel plate. 2. defect analysis 2.1 shot press in When the roller brush of shot blasting machine enters the end of a cycle, it will lead to the existence of wear. In the treatment of smaller steel plate, the shot material will follow the steel plate directly out of the shot blasting machine body. If there is no effective cleaning treatment, the shot material of the sheet material will be pressed after the stacking of the steel plate. In addition, due to the lack of shot blasting machine design, shot material is easy to appear in the position between steel plate and roller table in the process of processing. Because of the effect of self weight, the steel plate presses the shot material into the lower part, and enters into the steel plate after several times of rolling. 2.2 indentation of bottom roller The formation of the defects of the bottom roller indentation is that the bottom rolling surface is nodular, and the larger thickness of the steel plate appears indentation due to the high temperature on the lower surface. Causes of the surface nodulation of the bottom roller: there is a certain amount of oxide iron on some positions of the roller surface, and the increasing of the charging quantity causes the increase of the oxide scale, and then the accumulation in this position. At the same time, there is high temperature oxidation reaction under the soft condition of hot melt, and the roll surface nodule will increase. Under quenching or normalizing conditions, the layer oxide skin bonded on the roller surface is rolled by steel plate, and the layer by layer increases, and the density increases. In this case, the surface of the steel plate with larger thickness appears indentation under the influence of high temperature. In addition, the defects of drum and deformation at the bottom of the furnace will also have the problem of nodule. Source of iron oxide: one is outside the production link, the other is the abnormal situation in the furnace. The oxide skin outside the production link is the unclean shot blasting and the residual of shot material, because the design of shot blasting machine is unreasonable, the mechanical cleaning is not complete, the surface of steel plate has shot material, and there is oxide skin on the steel plate itself. The reason for the formation of iron oxide sheet in furnace is that the internal environment of heat treatment is abnormal and the residual oxygen is too large. The reason for the abnormal environment in the furnace is the quality problem of radiation tube. It can be checked by shutdown to determine whether it is caused by this reason. The furnace heating is carried out after mixing gas and combustion supporting air. The combustion in the radiation tube is realized by radiation. The sealing effect of the whole furnace is good. Therefore, the existence of internal oxygen is that air enters the inside when the furnace door is open. Because the furnace is designed as positive pressure and the furnace door is opened, nitrogen is used for automatic cleaning, so the probability of air entering into the furnace door is low; after the radiation pipe is treated for a long time with high temperature, the quality problems of the ceramic inner pipe, or the problems such as breakage and fracture due to the long service time, are caused, The reason for the metal appearance to be broken due to the lack of uniformity of heating may be due to the quality problems of the metal appearance itself. The burning through situation occurs in the work, which leads to the combustion air entering the inside from the damaged part. 2.3 extrusion deformation of side The deformation of the side extrusion is mainly due to the defects of the drum deformation in the roller table at the bottom of the heat treatment furnace. In the high temperature production process, the lower part of the steel plate contacts the drum at the bottom of the furnace and its gravity action will produce extrusion deformation under the movement in the furnace. The reason for the formation of drum drum is that the temperature difference between bottom roller and steel plate exceeds the standard, and the thickness of bottom roller wall is very small and the strength is relatively low. It is deformed when it contacts the steel plate due to the high temperature. 3. control measures 3.1 control of shot material pressing In order to effectively prevent the residual shot material on the surface of steel plate after shot blasting and prevent the shot material entering the furnace, generally, the scraper structure should be set at the outlet position of the shot blasting machine. At this time, the blowing device can be added at the outlet position to better clean the surface shot material; The following two points should be taken for pressing the shot material on the lower surface. One is that adding scraper in the cleaning room can prevent the existence of shot material on the lower surface of the steel plate; the second is to set up a supporting ring device on the surface of the conveying roller in the cleaning room of the shot blasting machine, which can effectively reduce the contact area between the steel plate and the roller, and prevent the pellet from entering the furnace. The above-mentioned shot blasting machine transformation can effectively prevent the pressing of shot material, eliminate these problems, and realize that the steel plate with thickness less than 50mm will not have any problem of shot pressing; the pressing of steel plate with thickness of more than 50mm generally appears on both sides of the steel plate. After treatment, the probability of shot pressing is reduced to less than 1%, which can improve the quality of steel plate, The productivity of shot blasting is promoted and the economic benefit is obviously improved. 3.2 control of the indentation of furnace bottom roller Strengthen the quality management of shot blasting to ensure that there is no residual and pressing of shot material on the surface of steel plate. The shot blasting effect reaches Sa2.5. According to the requirements of production process, the furnace cleaning can be carried out. According to the influence of the surface weight and friction force of the steel plate, the oxide skin can be crushed, and then the oxide skin will be removed before entering the furnace, so as to ensure the steel plate quality is qualified, and the service life of the bottom roller can be prolonged, and the indentation of the bottom roller can be eliminated from the root. After the above treatment, the treatment practice analysis of the indentation of the bottom roller is carried out for a long time. Under the condition that the temperature in the production environment is controlled below 900 ℃, there is no bottom roller indentation. When the production temperature is above 900 ℃, and the thickness is more than 30mm, the indentation of the bottom roller will be found, and the depth has been reduced from 0.3 to 1.0mm to 0.1-0.3mm, and the decrease is obvious. After the above treatment, the workload of manual grinding can be effectively reduced, the work efficiency is improved, and the surface nodular defects of bottom roller can be eliminated completely, which has high quality requirements. 3.3 control of extrusion deformation at the side To make the temperature of furnace bottom roll reach the uniformity standard, one is to raise the roller speed properly. The longer the steel plate contacts the roller surface, the lower the temperature will be, the temperature difference will increase, which will lead to the appearance of drum. If the low speed operation time is longer, the problem of roller table bending deformation will appear, and the speed can be improved to lower the temperature better, thus avoiding the problem of drum drum. Second, increase the swing amplitude appropriately. When the bottom roller rotates for one week, it can be determined as the best swing amplitude. At this time, the contact between the roller and the steel plate can be more uniform, and the heating of the roller table will become more uniform. Through installing the furnace offset control device, in the production of high temperature steel plate, it should be classified according to the thickness and time: the plate with thickness no more than 100mm is normally installed in the furnace; the quenched (positive) fire plate with thickness greater than 100m shall be padded on one side of wood block when aligning, so that the steel plate will be offset 200-300mm to the side. Through the implementation of the control measures of offset charging, the working surface of the bottom roller can be used alternately, and the temperature difference on the bottom roller position can be reduced better, and the heating is more uniform, and then the problem of drum drum of bottom roller can be prevented and the whole production level can be promoted. After the above treatment measures, the quenching furnace produces 145 pieces of 2725t steel plates with thickness of 150 mm, and has been put into the furnace 335 times. After the production of steel plates in the enterprise, the quality level of the side is relatively high, and there is no defect of side extrusion deformation. 4. conclusion In conclusion, the causes of surface quality defects of medium thick steel plate heat treatment are analyzed, and necessary treatment measures are taken. After some time of test, it is found that the quality improvement of steel plate is obvious, such as the pressing rate of shot material is controlled below 1% for a long time, the depth of the bottom roller indentation is kept at 0.1-0.3mm, the manual grinding quantity is small, and the edge of steel plate has no extrusion deformation defects, The overall quality level is very high, which brings high economic benefits to the enterprise. Author: Yugang China Stainless Steel Plates Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com) Reference [1] Xujianxiang, wuyuwan. Analysis and solution of surface quality problems of shot blasting steel plate in heat treatment line of medium thick steel plate [j]. Internal combustion engine and accessories, 2019, (12): 45-47 [2] Dong Zhanbin, Wang Xuesong, Liu Xiaohui, et al. Simulation and application of heat treatment furnace washing test of medium thick steel plate based on BP neural network [j]. Rolling steel, 2015, (2): 65-68

Elbows, also known as “ells,” are used to change the direction of a pipe system. An elbow typically features a 45, 90 or 180 degree bend, although other angles are also available. Elbows come in a variety of diameters and are generally threaded for connectivity. A common example of an elbow fitting in the home is the piece that extends from the wall of your shower to which the shower head connects. pipe-elbows Wall thickness: SCH5 to SCH160When the two ends differ in size, the fitting is called a reducing elbow or reducer elbow. Elbows are categorized based on various design features as below: Long Radius (LR) Elbows – radius is 1.5 times the pipe diameter Short Radius (SR) Elbows – radius is 1.0 times the pipe diameter 90 Degree Elbow – where change in direction required is 90° 45 Degree Elbow – where change in direction required is 45° Size range: 1/2 to 56 inches (DN 15 to DN 1,400mm) Degree: 22.5 Deg, 45 Deg, 90 Deg, 180 Deg pipe-elbow-draws Pipe elbow draws Manufacturing standards: ANSI, ISO, JIS and DIN Process: butt welding, seamless Type: Long radius, Short radius, Large size Pressure: class 3000, 6000 and 9000

Ring Type Joint Flange is a method of ensuring leak proof flange connection at high pressures. A metal ring is compressed into a hexagonal groove on the face of the flange to make the seal. This jointing method can be employed on Weld Neck, Slip-on and Blind Flange. ring-type-joint-flange Standards: ANSI, MSS, API, AWWA, DIN, JIS, BS and GB. Pressure classes range: from 150lbs to 2,500lbs. Sizes range: From 1/2″ to 84″. Materials: Carbon steel, stainless steel and alloy steel. Printing: Carbon steel and alloy steel with yellow print, black print, oil or zinc. Packing: Plywooden case. Standards, Dimensions & Weight Dimensions of Ring Joint Facings Ring Joint Facings ASME/ANSI B16.5 & B16.47-1 Ring Joint Facings ASME/ANSI B16.5 & B16.47-2 Ring Joint Facings ASME/ANSI B16.5 & B16.47-3 Ring Joint Facings ASME/ANSI B16.5 & B16.47-4 Specifications of :Ring Type Joint Flange rjf-b16-16-47 Size: 1/2” to 60”, DN 12mm to DN 1500mm Pressure class: Class 150 to Class 2,500, PN 2.5 to PN 250 Facing: RF / RTJ MATERIAL: Cabon steel: A105, A350 LF2 Stainless steel: A182 F304/F304L/F316/F316L/F321 Alloy steel: F11, F12