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When the stainless steel pipe is packed and transported, it is necessary to act according to scientific and reasonable rules to maximize the integrity of the stainless steel pipe in the course of travel. The following are the rules of operation. When storing stainless steel pipes, stainless steel pipes can’t be directly stacked on the ground, steel plate or cement floor. The distance between the first tier and the ground is not less than 0.20m. In order to prevent the damp, dust and pollution of the stainless steel pipe, the stainless steel pipe is forbidden to be placed in the dust and wet place. The ends of the stainless steel pipe must be protected by the plastic paper or the packing bag to avoid the dust entry. Next, the rack or stack should be arranged neatly and clearly marked. Stainless steel pipes should be placed on the designated rack or stack according to the furnace numbers, varieties, specifications and materials. The same material rack or stack can not store stainless steel pipes with the same specifications or similar material shapes and different furnace numbers. To avoid bending or pipe damage, the stainless steel pipes (or bundles) should be placed on the sleepers at the proper intervals and on the same level to ensure that one end of the stainless steel pipe is aligned. Stainless steel pipes, which are cold rolled, cold drawn or annealed, can not be stored in open air. If the storage conditions are limited, and outdoor storage is needed, appropriate protective measures should be taken to prevent corrosion of rainwater, snow and fog, and dust pollution. In the transport, transport compartment to keep clean and free of stones, bricks and other hard objects, in order to avoid the Luo injured stainless steel pipe. For bulk or bundled stainless steel pipes, the sleepers should be cushions at the bottom of the carriage. For vehicles that use steel brackets with flat cars, we must install protective rubber pads on the sides of stainless steel pipes. When the stainless steel pipe or pipe bundle is transshipped in the factory area, the isolation sleepers should be properly placed, and at least two places are placed along the length of the steel pipe. The padding wood should be placed perpendicular to the steel pipe and up and down right. The pads should be placed horizontally and well. The finished stainless steel pipe, delivered for long distance transportation, should be tied firmly after loading. If the wire rope or similar hard material is used, the protective isolator on the steel pipe binding or the protective isolation on the wire rope should be added to avoid the damage to the surface of the stainless steel pipe and prevent the direct collision between the stainless steel pipe and the carriage. Friction and front and back move. To avoid damage to the steel pipe in the process of bundling and transportation, we must maintain consistency in binding. The same bundle of steel pipes should not be mixed with furnaces and steel pipes if they are the same as those of the furnace number, the same steel grade and the same specification. The weight of each bundle of stainless steel pipes should not be more than 50 kilograms. The weight can be increased by the user’s consent, but the heaviest weight should not be greater than 80 kilograms. For the flat end stainless steel pipe bundling, one end should be kept aligned, the difference between the end of the pipe end is less than 20mm, the length difference of each bundle of stainless steel pipe is less than 10mm, but the length difference of each bundle of steel pipe which is ordered according to the usual length is less than 5mm, and the longest and the secondary length of a bundle of steel pipes is not more than 10mm. When the stainless steel pipe is put into the container, the cardboard, plastic cloth or other moistureproof material should be placed on the inner wall of the container. The container must be kept tight without water seepage. For stainless steel pipe with container packing, a sign should be attached to the container. The corresponding signs should be hung on the outer end of container. If the stainless steel pipe has special packaging requirements, it shall be agreed by the supplier and the buyer. When loading stainless steel pipes, in order to avoid depression, indentation, scratching, and pipe damage, a steel wire rope with a disk crane, a nylon belt or a protective isolator should be used during loading. It is not allowed to pull out the nylon belt or the wire rope under the pressure of the steel pipe or the pipe bundle. When loading stainless steel pipes for automobile transportation, the nylon belt or wire rope must be kept stable when the loading conditions are restricted, in order to prevent the strong collision or roll between the stainless steel pipes or the bundles and the barbarous loading and unloading. For the marking of packing, each bundle of stainless steel pipes wrapped in bundles should be hung on each end of the steel pipe with 1 signs. The stainless steel pipe packed in the container shall be hung in and out of the container with 1 signs, indicating the name of the product, the contract number, the model, the furnace number, the steel grade, the bundle number, the weight, the length, the count and the date. In the package case, we must have the product inspection certificate or material analysis report. If medium and small steel, wire rod, steel bar, steel steel pipe, steel wire and wire rope, etc., it can be stored in a well ventilated material shed, but must be on the mat. Second, there are some small stainless steel, thin steel plate, steel strip, silicon steel sheet, small diameter or thin wall steel pipe, all kinds of cold rolled and cold drawn steel. Materials and metal products with high price and corrosion resistance can be put into storage. Third the warehouse should be selected according to the geographical conditions, usually use the ordinary closed storeroom, that is, the roof has a wall, close doors and windows, with a ventilation system. Fourth, do not stack with corrosive materials such as acid, alkali, salt and cement in warehouses. Different varieties of steel should be stacked separately, so as to prevent confusion and prevent contact corrosion. Fifth, large scale steel, rail, steel plate, large diameter steel pipe and forgings can be stacked in open air. The site or storehouse for stainless steel pipe should be selected in a clean and well drained place, away from factories and mines that will generate harmful gases or dust. Weed and all kinds of sundries should be cleared on the site to ensure that the stainless steel is clean. The requirement for storehouse is clear and ventilated, rainy days can be closed to prevent dampness, and often keep proper storage environment. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel pipes should have different forms of packing according to their product type, finish, size and transportation mode. Because the stainless steel pipe is usually the pipe, the pressure pipe, the mechanical pipe and the decorative pipe, and the stainless steel pipe can be processed, annealed and pickling, cold working, grinding and polishing and decorating, so the size and the processing luminosity of the stainless steel pipe are very complex, so it should be especially injected in order to purchase order. The corresponding packing, marking and shipping methods. If there is doubt about some shipping methods, we must do well in communication work. Stainless steel pipes are often packed, transported by bags, boxes or protective containers. The outer diameter of the stainless steel pipe with a size larger than 6 inches can be transported either in bulk or in packaging, or without packaging and transportation. The best packing method is determined by length size, outer diameter, wall thickness, finish and transportation. Most of the polishing pipes are packed in wooden boxes or other suitable materials. It is necessary for a stainless steel pipe to be bundled, because when the stainless steel pipe is transported, the amount of the pipe may lead to the risk of bending, extrusion or distortion during the handling of the pipe. In addition, some other auxiliary measures are required. Bales are usually fixed with flat steel ribbons, but other suitable materials can also be used. The number of fixed nodes depends on the length and weight of the bales. Some stainless steel pipes may have special smoothness requirements, special orders, special modes of transportation, or other factors. In this case, special containers are required to be prepared, such as paper pipes, cartons, wooden cases, or similar containers. During the transportation process, stainless steel pipes must be protected and covered. But if the outside diameter or inner diameter surface is the key feature, the protective cloth will be added to the railway transport equipment, and the waterproof cloth will be added to the truck. A certain degree of dirt and oxide is permissible, whether it is no coating, or galvanized pipe, or a non spray pipe, or a pipe that is sprayed with a non dry oil coating. Many ordinary stainless steel pipes are transported by unprotected open wagons. In addition to the mess outside, stainless steel pipes are usually kept neat, and there is no need to prepare separate items for shipment. Fixed or separated stainless steel pipes can be transported into cargo, separated into a certain size and quantity, requiring additional handling and materials. Adding stainless steel pipes to a closed truck or truck requires extra handling, and a small stainless steel pipe with a small size can also have extra labor costs. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

In the practical application of stainless steel pipes, there will be no other stainless steel pipes or flanges, fittings. At this time to meet the requirements of the use, it is necessary to ensure that the quality of the butt joint between the stainless steel pipe and the butt parts reaches a certain standard, and the following points are concerned. One is the connection between the stainless steel pipe, tube group pair, inner Nezi gap should be less than 0.1mm. In order to ensure the size of the group, prevent welding deformation and dislocation, affect the normal welding and weld formation, most of the positioning welding is carried out. The distance between the location of the welding spot depends on the number, thickness and type of the welded joint. Because stainless steel has larger linear expansion coefficient and larger welding distortion than that of low carbon steel, spot welding should be small. For thinner and easily deformable weldments, the spacing should be small. For the welded parts with large steel and large cracks, long welding points should be used to avoid the cracking of the solder joints, and the size of the welding spot should be shortened. Positioning welding should ensure complete penetration and reliable connection, low level of solder joints and not too long, too wide and too high to prevent the influence of normal welding and weld formation. In order to avoid oxidation of the spot welding point, the argon gas should stay at the spot welding spot to solidify without oxidation during spot welding. If spot weld cracking is found, it should be disposed in time to prevent defects from remaining in the weld and affect the welding quality. During welding, because the affinity between stainless steel tube and oxygen is very large, the inner side of the pipe must be protected by hydrogen, so as to ensure that the inner wall weld is not oxidized. It also prevents welding defects from overheating of molten metal, and can be filled with argon by whole pipe, which is relatively simple. However, with the increase of the length of the pipeline, the waste of argon is much more wasteful. In general, subsection assembly and welding are adopted, and a small amount of intermediate joints are blocked by soluble paper on both sides of the welded pipe, and the soluble paper is dissolved in water pressure test. Its intersection is the butt of the thick and thin tubes. The butt of stainless steel pipes with different thickness appears on the wall thickness of the pipe head of the equipment. If the treatment is not appropriate, there will be problems of unweld, welding or welding. The main reason is that the thin wall tube has been melted when welding, and the thick wall still does not reach the melting point temperature. To prevent such problems, it is necessary to grind the thick wall tube into 45 degree groove and add the thin pipe to 20 degree groove, so that after welding, it can completely meet the quality requirement. The third is to weld the Trident pipe. The key point is to cut the material accurately, assembly is reasonable, and the groove must be machined, otherwise it will not meet the requirement. When the material is cut off, the aperture of the opening should be equal to the inner diameter of the connecting pipe, and then the groove must be made for connecting pipe. After the process of assembly spot welding, it should be carried out by a better welder with a better welder, L / 4 each of the three forked ports, four angle changes, the speed of the wire feeding is different, the key position is 90 degrees at the two pipe angle. The welding speed here should be slower to be welded, then the welding speed should be accelerated and the angle of the workpiece is kept from 75- to 80. Between degrees. After welding, the inner surface should be smooth and smooth. Finally, the flange and stub end welding, at this time the use of looped flange connection, stub end and pipe welding, welding, spot welding point 180 degrees, find stub end and pipe concentric, can spot welding other fixed points. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

In the production process of stainless steel seamless pipe, it is necessary to pay attention to the production characteristics of the pipe. As long as these characteristics are fully utilized, the quality of the stainless steel pipe produced can be as good as possible. Plastic characteristics of stainless steel pipe The martensitic stainless steel is not difficult to perforate when it is a single austenite structure at high temperature, but the perforation performance is reduced when there is biphasic structure. pipe blank heating temperature is usually 1130-1160 °C, the furnace tail temperature is lower than 900 °C, the final rolling temperature is greater than the critical point transition temperature, low carbon is not less than 850 °C, high carbon is not higher than 925 °C. With the increase of carbon content in martensitic stainless steel, the strength and hardness of stainless steel increase, and the plasticity decreases. When cold drawing, the core plug should be used as far as possible to draw. This is because it is easy to burst after empty drawing. The high temperature plasticity of austenitic stainless steels is related to the residual α phase. Plasticity generally weakens as the α phase increases. In addition to the α phase, there are other residual phases in the austenitic stainless steel, such as various forms of carbides, intermetallic compounds, and the like. The plasticity of these extra relative stainless steel pipes has an influence, and the degree of influence depends on their quantity and status. When heated, the excess phase appears as a network distribution on the grain boundary, which will significantly deteriorate the plasticity of the stainless steel pipe. Austenitic stainless steel pipes have low plasticity at high temperatures and large deformation resistance. Special attention should be paid to the selection of reasonable deformation parameters and temperature parameters when using oblique rolling piercing. After the austenite stainless steel pipe is treated by solution treatment, it shows a single-phase austenite structure. Its characteristic is that σb is high, but the σs is low, the ductility and toughness are relatively large, and the cold deformation performance is good, so it is desirable The amount of deformation of the pass. However, the work hardening during cold deformation is large, so the processing performance is poor. Ferritic stainless steel is a single-phase structure and has no critical transition point (phase transition). Therefore, the long heating time of the pipe and the high temperature increase the grain size seriously, resulting in a significant decrease in the plasticity of the steel. The maximum temperature of pipe heating is 1000 to 1060°C. Steel has good plasticity (perforation) in this temperature range. The temperature before the cold-drawing hammerhead is 700-850°C. When heating, it is necessary to prevent carburizing, and after hammering, water quenching is performed. Since ferritic chromium stainless steel has room temperature brittleness and poor cold working properties, it is easy to crack and pull out when cold drawing. Therefore, it is best to draw under a certain temperature condition (see the drawing of the pipe), and the pulling speed should not be too high. When cold-rolled ferritic stainless steel pipe, the degree of deformation of the pipe during rolling is not more than 40% to 48%. In later passes (after surface preparation and heat treatment), the degree of deformation can be increased to 55% to 65% depending on the degree of grain refinement. In order to avoid cracking of the steel pipe during rolling, the temperature rise of the pipe during rolling is advantageous, so in most cases the stainless steel pipe is rolled without the emulsion cooling tool and metal. Stainless steel pipe deformation resistance Both austenitic and martensitic stainless steel pipes have high deformation resistance, a relatively large work hardening tendency, and slow recrystallization at high temperatures. Therefore, special attention must be paid to equipment and motor capabilities when cold-rolling such stainless steel pipes. Ferrite or hemiferous low-carbon stainless steel pipes have the same deformation resistance as ordinary carbon steel. Broad exhibition The wide spread of stainless steel pipes refers to the degree of transverse deformation, which is generally large. The width of martensitic stainless steel pipes is 1.3 times that of carbon steel, that of austenitic stainless steel is 1.35 to 1.5 times, and that of ferritic stainless steel is 1.55. -1.6 times. Therefore, it is necessary to pay attention to controlling the horizontal deformation degree of the stainless steel pipe during the oblique rolling and piercing, and to obtain a smaller ellipticity. The cold and hot-rolled stainless steel pipe has a larger ellipticity of the hole shape, and should take a smaller amount of deformation in order to prevent the occurrence of defects such as ears. In the case of no tension reducing, the wall thickness of the stainless steel pipe is relatively large and decreases. The hole machine ovality to take larger. Stress sensitive Ferritic stainless steel has brittleness at room temperature, cold processing is highly sensitive to stress, and the stress sensitivity during hot rolling is low, and water quenching can be performed after rolling. Martensitic stainless steels are more sensitive to cracks. Cooling after hot rolling can not be too fast. Usually, pile cold is used. Austenitic stainless steels have low sensitivity to cracks and can be water quenched after hot rolling. Thermal conductivity The low-temperature thermal conductivity of stainless steel pipes is relatively poor, while the linear expansion coefficient is greater than that of carbon steel. In order to ensure the heating quality of the stainless steel pipe, low-temperature heating at a low temperature is used. Antioxidant Because the stainless steel pipe material has good oxidation resistance, the scale formed during heating is relatively small. However, the iron oxide skin contains chromium and nickel oxides and is very dense, and it is difficult to carry out pickling during cold working. Usually HF+HNO3 is used for pickling or alkaline pickling. Bonding tendency Stainless steel ferritic, duplex stainless steel and austenitic stainless steel are susceptible to stick-rolling during rolling and reduce the surface quality of the stainless steel pipe. The use of cast iron rollers in the hot-rolled finishing mill can reduce sticking. In addition, the rational use of cooling water to cool the rollers is also critical. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

When do stainless steel pipe need passivation? Conventionally, when the stainless steel pipe is corroded after the welding process and subjected to strong pollution, it must be passivated. The preferred passivation method is as follows. In the case of stainless steel pipe sections with straight pipes and without branch pipes and hand-operated stainless steel pipes and fittings, they may be treated on site in the workshop using a passivating paste. The specific method is to weld the welded stainless steel pipes or armored parts. The polishing is done in advance. The polishing tool is a stainless steel polishing brush or a chuck-type page wheel. This can remove the oxides that remain on the surface of the stainless steel pipe and the surrounding oxide, restore the original color of the stainless steel pipe, and then use the brush for the passivation paste. Evenly smear on the surface to be treated, according to the appropriate ambient temperature, to determine the passivation time, usually the ambient temperature is less than 28 ° -35 ° for 1 hour, the ambient temperature of 15 ° -27 ° 2 hours, low It is 3-4 hours at 15°. After the passivation time is reached, it is not possible to use pure water to flush directly, because the passivation paste is a strong acid, which will not only damage the surrounding construction sites, but more seriously cause the pollution of the water environment. The correct way is to use a clean rag or other tools similar to rags to wipe off the passivation paste first, then rinse with water. And while flushing, use a scouring pad to wipe the passivation point until it is confirmed that there is no residue of the passivation paste, and the weld and the other parts of the stainless steel pipe are bright. Passivated stainless steel pipes and armored parts are measured with a passivation thickness gauge, for example, readings above 60 are considered acceptable. It should be noted that since the passivation paste is a strong acid, it is a truly dangerous product. It must not only be kept by special personnel, but must be handled by the user. The operator must be aware of the requirements for passivation and ventilation when using it. Meet the corresponding passivation conditions. Stainless steel pipes should also be inspected for quality after passivation. Chemical inspections can destroy the passivation film of stainless steel pipes, so they are usually tested on a sample plate. There are two methods, one of which is copper sulfate titration test, using 8g CuS04 + 500mLH20 +2 ~ 3mLH2S04 solution dropped onto the surface of stainless steel pipe samples to ensure that the wet state, such as precipitation does not appear within 6 minutes is qualified. The second is the titration test of potassium ferricyanide, which can use 2mLHCl+1mLH2S04+1gK3Fe(CN)6+97mLH20 solution to drop on the surface of the stainless steel pipe sample. The quality of the passivation film can be identified by the number of blue spots and the length of time. High and low. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The solution treatment of stainless steel pipes are very powerful, mainly reflected in three aspects. The following is a detailed description of austenitic stainless steel pipes. The austenitic stainless steel tube is softened by solution treatment. Usually, the stainless steel tube is heated to a temperature range of 950-1150°C and held for a certain period of time, so that the carbides and various alloy elements in the material are completely and uniformly dissolved in the austenite. In the body tissue, followed by rapid quenching and cooling, carbon and other alloying elements are too late to precipitate, and high-purity austenite structures can be obtained. This is called solid solution treatment. The role of solution treatment mainly has three aspects. The first is to make the stainless steel tube structure and composition maintain uniform, which is very important for the raw material, because the rolling temperature and cooling rate of the sections of the hot-rolled wire are not the same, it is easy to lead to inconsistent organizational structure. At high temperatures, the atomic activity will increase, the σ phase will dissolve, the chemical composition will tend to be uniform, and a highly uniform single-phase structure can be obtained after rapid cooling. The second is to eliminate work hardening, which is conducive to continued cold processing. After solution treatment, the twisted lattice will recover, the elongated and broken grains will recrystallize, the internal stress will be eliminated, the tensile strength of the stainless steel tube will decrease, and the elongation will increase. The third is to restore the inherent corrosion resistance of stainless steel pipes. Because of cold working, carbides are precipitated and lattice defects are caused, so that the corrosion resistance of the stainless steel pipe is reduced. After the solution treatment, the corrosion resistance of the stainless steel pipe recovers to the best condition. For stainless steel pipes, the three key elements of solution treatment are temperature, holding time and cooling rate. Solution temperature is mainly determined by chemical composition. Generally speaking, there are many types of alloying elements and high-content grades. The solution temperature will increase to some extent. In particular, stainless steel grades with high manganese, molybdenum, nickel, and silicon content can only achieve the softening effect by increasing the solution temperature and completely dissolving it. However, in the case of stabilized steels, such as 1Cr18Ni9Ti, the carbides of the stabilizing elements are sufficiently dissolved in the austenite when the solution temperature is high, and precipitate at the grain boundaries in the form of Cr23C6 during the subsequent cooling, resulting in the formation of intergranular corrosion. In order that the carbides of the stabilizing element do not decompose and solid-solve, the lower limit solution temperature is generally used. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Due to the excellent performance of the seamless stainless steel pipe, the use of the stainless steel pipe is very popular and the price is very reasonable. Therefore, in the downstream spot market, there are sometimes fake stainless steel seamless pipes, which is the fluid pipe. In fact, the pipe is treated high. Frequency welded pipe. The treatment method of the high-frequency welded pipe is to use the special equipment or planning or grinding away the original weld. Another method is to hot-roll the welded pipe. Some unscrupulous merchants use such tubes to deceive buyers. Here are the characteristics of this type of pipe. First of all, those that are shaved or worn off will leave traces, and some are still very obvious, sometimes more obvious after the rust removal with tools; this kind of pipe manufacturers are all marked on the quality certificate provided because they are afraid to take responsibility. The fluid pipe is not used to mark seamless pipes for fluids; merchants selling such pipes usually have to settle according to the theoretical weight, but the real domestic seamless steel pipes are beyond the standard thickness, generally weighing, and there are more professional ones. That is, to do flaw detection and component inspection, but these two methods are more limited because it is difficult to identify the hot rolled welded pipe. The seamless stainless steel pipe is a heat-shrink processed product, and the appearance is also more beautiful so that the overall performance of the stainless steel tube can be increased. The common welded pipes in the market mainly include straight seam welded pipe, spiral welded pipe, and seamless welded pipe. However, straight welded pipe and spiral welded pipe are very well recognized. The difference between seamless welded pipe and seamless steel pipe is mainly reflected in the following aspects. First, the welded pipe is usually of a fixed length and is usually 6 meters, 9 meters or 12 meters. The length of seamless steel pipe is very small because there is a lot of fixed-length factory increase. Secondly, from the cross-section of the stainless steel pipe head, if there is rust, wipe it clean. If you look closely, you will find the welding area. If pickling is done, it will be more obvious. In addition, it should be noted that in general, thick-walled steel tubes do not exhibit welded pipe counterfeiting, and only thin-walled steel tubes are confusing. In fact, they can be distinguished. It can be observed whether the wall thickness of the stainless steel pipe is even, because the seamless steel pipe is made of perforated round steel, so the wall thickness of the seamless steel pipe usually deviates, and the welded pipe is subjected to welding wire processing or thermal expansion and other procedures, but because The raw material is stainless steel strip, so the wall thickness of the welded pipe is very uniform. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The corrosion of stainless steel pipe is mainly caused by the material properties, surface conditions, medium properties, pH value, temperature, flow rate and time. In addition, the factors affecting the properties of stainless steel include composition, crystal structure and passivation. Membrane and so on. The composition and crystal structure of the stainless steel pipe and the contained impurities determine the corrosion resistance of the material. For example, the addition of niobium and titanium in a stainless steel pipe can effectively prevent the formation of chromium carbide, which enhances the grain boundary corrosion resistance of the material. The proper combination of molybdenum and chromium can effectively stabilize the passive film even when chloride is present in the environmental media. Many grain boundary corrosions are caused by heat treatment, and stainless steel pipes heated to a certain temperature during the welding process will generate a deposition of chromium carbide on the grain boundary. Therefore, chromium is lost in the area close to the chromium carbide. Increase the liveliness of chromium in the area. If there is an aqueous solution condition, a primary cell with bare chromium as the anode and stainless steel as the cathode will be generated. Larger cathode area will form anode control, so the corrosion is very serious, resulting in intergranular cracking or pitting. This is called intergranular corrosion of the welded joint. This type of stainless steel is also an activated steel. Using low-carbon austenitic stainless steel can reduce this problem. Passivation film is the main barrier to protect stainless steel, but on the other hand, passivation characteristics of the metal or alloy, the stronger the passivation ability is, the higher the sensitivity to pitting corrosion, stainless steel is more prone to pitting corrosion than carbon steel. . The occurrence of pitting corrosion is related to the presence of active anions or oxidizing cations in the medium. Most of the pitting events occur in chloride- or chloride-containing media. Experiments have shown that, under anodic polarization conditions, pitting corrosion can occur in the metal as long as it contains chloride ions. Therefore, the chloride ion is also called the “exciting agent” of the pitting corrosion, and with the increase of the chloride ion concentration in the medium, the pitting potential decreases, so that the pitting corrosion easily occurs, and then it is easy to accelerate. The pitting corrosion rate of the metal in the stationary state of the medium is greater than when the medium is in the flowing state. The flow rate of the medium plays a dual role in slowing down the hole erosion. Increasing the flow rate on the one hand is conducive to the transport of dissolved oxygen to the metal surface, making the passivation film easier to form; on the other hand, it can reduce the chance of sediment deposition on the metal surface, thereby reducing the occurrence of Hole erosion opportunities. The induction period for the occurrence of pitting corrosion is usually from a few months to a year depending on the circumstances. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

When stainless steel pipes are cold-drawn or cold-rolled, some defects will inevitably occur. These defects will affect the quality of the finished stainless steel pipe products. Therefore, preventive measures must be taken for the formation of these defects. The quality defects of the cold-drawn stainless steel pipes mainly include uneven wall thickness, outer diameter, surface cracks, surface straightness, and scratches. The unequal wall thickness of the cold-drawn stainless steel pipe is affected by factors such as the wall thickness accuracy of the pipe blank, the method of extubation, the deviation of the drawn center line, the shape of the hole, the deformation process parameters, and the lubrication conditions. During the formation process, pay attention to the degree of wear of the fitting and drafting. In addition, in order to reduce the formation of cracks on the surface of drawn stainless steel pipes, suitable stainless steel pipe blanks should be used to repair the surface defects of stainless steel pipe blanks. During the pickling of stainless steel pipe blanks, it is necessary not only to avoid pickling but also to avoid the formation of pits or hydrogen. Crisp, but also to avoid the lack of pickling, to prevent the oxide scale is not clean, when used, but also to ensure the quality of stainless steel pipe annealing, use a reasonable method of extubation, select the appropriate deformation process parameters and tool shape, but also improve the extraction center Line adjustments and inspections. Enhanced stainless steel pipe pickling quality and lubrication quality, to ensure that the hardness and uniformity of the tool and the surface finish will help reduce the formation of straight stainless steel pipe and scratches. Cold rolled stainless steel pipe quality defects and prevention, the main quality defects of cold-rolled stainless steel pipe include stainless steel pipe wall thickness unevenness, outside diameter, surface cracks, wrinkles, and folds, etc., enhance the accuracy of stainless steel pipe wall thickness is to ensure cold Rolled stainless steel pipe wall thickness is an important condition. To ensure the accuracy of wall thickness and pickling quality of stainless steel pipe, lubrication quality and the surface finish of rolling pipe tools is an important guarantee to enhance the accuracy of cold-rolled stainless steel pipe wall thickness, stainless steel pipe blanks should be avoided pickling or pickling, stainless steel The surface of the pipe blank is formed with pockmarks or residual iron oxide skin. The processing measures the cooling of the rolling pipe tool and the inspection of the surface quality of the tool and replaces the mandrel bar and the rolling groove block that do not meet the requirements. Therefore, the measures to reduce the rolling force are all beneficial to increase the accuracy of the outer diameter of the stainless steel pipe, including annealing the stainless steel pipe, reducing the amount of rolling deformation, enhancing the lubrication quality of the stainless steel pipe and the surface finish of the pipe tool, etc. Materials with high strength and hardness are used to produce rolling pipe tools, and cooling and inspection of rolling pipe tools are strengthened. If serious abrasion of the rolling pipe tools is found, it must be replaced in time to avoid the occurrence of an ultra bad condition of the outer diameter of the stainless steel pipe. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel pipe in the passivated state will still have a certain ability to react because the passive film is always in a dynamic equilibrium state of dissolution and repair and passivation. When the stainless steel pipe contains the active anion in the environmental media, the equilibrium state is easily destroyed, and the dissolved state at this time is more dominant. The reason for this happening is that the active anions such as chloride ions are preferentially adsorbed on the passive film on the surface of the stainless steel pipe, and squeeze out the original oxygen atoms, and then combine with the cations in the passive film to form soluble chlorides. The resulting result is that small etch pits will be formed at specific spots of newly exposed base metal. Such small pits have pore diameters of about 20-30 μm. These small pits are called pit nucleuses. Understand the formation of active centers for pitting. The presence of chloride ions can directly destroy the passive surface of the stainless steel pipe. Usually, the passivation area of the surface of the stainless steel pipe decreases with increasing chloride ion concentration. In practical applications, when the anode potential in the environmental medium reaches a certain value, the current density will suddenly become smaller, which indicates that the surface of the stainless steel pipe has started to form a stable passive film, the corresponding resistance will be relatively high, and at a certain potential Long-term maintenance within the region. However, as the concentration of chloride ions in the environmental media increases, the critical current density increases, the primary passivation potential also increases, and the passivation zone is reduced. The explanation for this characteristic is that in the passivation potential region, the chloride ions compete with the oxidizing species and enter the thin film, thereby forming lattice defects and reducing the resistivity of the oxide. Therefore, in the presence of chloride ion in an environmental medium, neither passivation nor passivation is easily maintained. While the partial passivation film of the stainless steel pipe is damaged, the rest of the protective film remains intact, which enables the pitting conditions to be achieved and strengthened. According to the electrochemical formation mechanism, the stainless steel in the activated state has a much higher electrode potential than the passivated stainless steel. The electrolyte solution achieves the thermodynamic conditions of electrochemical corrosion. The activated stainless steel becomes the anode and the passivated stainless steel serves as the cathode. The corrosion point involves only a small part of the metal, while the other surface will be a large cathode area. In the electrochemical reaction, the cathode reaction and the anode reaction are carried out at the same speed, so the corrosion rate concentrated at the anode etching point will be very fast, and the penetrating effect will be obvious, so that pitting corrosion will be generated. Source: China Stainless Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

The so-called acid-resistant stainless steel plate is actually a stainless steel material that can resist acid corrosion in all kinds of highly corrosive acid media. The acid corrosion resistance of the acid-proof stainless steel plate mainly depends on the chemical composition of the stainless steel plate, such as nickel, chromium, molybdenum and copper. And other alloying elements. Usually the corrosion resistance of acid-resistant stainless steel plates in oxidizing acids is relatively good, while the corrosion resistance in reducing acids is relatively poor. The oxidizing acid is typically nitric acid and sulfuric acid, and the reducing acid is typically hydrochloric acid. The acid-resistance stainless steel plate has relatively large plasticity and toughness. The problems that occur during the drilling of the acid-resistant stainless steel plate are mainly due to the fact that it is not easy to break the chips. This will seriously affect the smooth inflow of the cutting fluid. The temperature of the cutting zone is relatively high, and the tool durability is very high. Low, productivity is also relatively low. When drilling, the cutting load will be relatively large, and the chips will consume a very large amount of energy. Together with the high-temperature strength and hardness of such stainless steel plates, the cuttings are not easily broken when they are cut off; and the cold hardening phenomenon also occurs. It can be very serious, the surface hardening degree of the stainless steel plate can reach more than 100%, the thickness of the hardened layer reaches 0.1-0.2mm. The acid-resistant stainless steel plate has a low thermal conductivity of only 1/3-1/4 of that of carbon steel, a very high temperature in the cutting zone, a strong affinity with other metals, and a hard spot in the material. Increase the wear speed of the tool. In order to solve the problem of chip breaking when drilling acid-resistant stainless steel plates, there are manufacturers who specialize in the research and development of new types of acid-resistant stainless steel chip breaking drills. When they are drilled, the chip length is about 100mm and they are discharged from the hole with a “fireworks” shape. The chip breaking effect is very high. Not bad. The main point of this “fireworks” shaped chip in the drilling process is to make the chipping point in the critical chipping state; the second is to properly grind the drill tip height and arc radius; the third is to drill The hole position should be selected appropriately, and with a proper amount of feed and a lower cutting speed, the chip is naturally broken in the obliquely twisted state. In general, when using an acid-resistant stainless steel chip breaking drill, it is necessary to use a lower cutting speed and a larger feed rate, which is really beneficial for achieving the purpose of chip breaking. Source: China Stainless Steel Plate Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

In recent years, as people have increasingly valued the safety and service life of materials, stainless steel corrugated hoses have been used in large numbers in the selection of gas pipe materials. Such pipes can be used in gas, liquefied petroleum gas, natural gas, and biogas. Pipeline connection application. The advantages of stainless steel gas bellows are as follows. The first is that stainless steel corrugated hose has good construction performance, reasonable organization structure and very stable performance. It belongs to thin-walled hoses, and its overall weight is relatively light, which can effectively reduce the load of construction operations and reduce construction time. Followed by the stainless steel tube material quality and durability, beautiful appearance, easy installation and removal. Stainless steel bellows have soft hand, high strength, good elasticity, and high fatigue resistance. The performance of the stainless steel bellows is also safe and reliable, and the quality is guaranteed. Taking into account various factors such as the actual working pressure of the bellows, the use environment, and the use conditions, all parameters have undergone rigorous calculations and repeated experiments to ensure that the stainless steel bellows are used at work. Security. Stainless steel bellows are available in a wide variety of specifications and at reasonable prices. The scope of application of stainless steel bellows is as follows. Non-sizing stainless steel corrugated pipe for fuel gas is suitable for natural gas, artificial gas, liquefied petroleum gas, and other gas sources of gas pipeline system. It will lead to new type of gas pipelines from indoor riser valves. Corresponding advantage is that the outside of the stainless steel corrugated hose is covered with soft PVC material, and a protective sleeve is formed after being coated. The material functions are anti-aging, anti-ultraviolet aging and flame retardant. It can also meet the user’s personalized needs, using a variety of ways such as wall-buried, dark-filled, and surface mounted. Corrosion resistance is very strong, and because it is stainless steel, it can guarantee a safe life of half a century. Stainless steel bellows are also compensated to effectively prevent gas leaks caused by earthquakes and building settlement. Stainless steel bellows are also very easy to bend and can bend and pass freely in narrow spaces. In general, the advantages of stainless steel corrugated hoses are: easy installation, reliable connection, corrosion resistance, no gas blockage, good flexibility, long service life, and the ability to bend freely without deformation or obstructing gas. Source: China Stainless Steel Corrugated Hose Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)