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The installation method of stainless steel pipe is basically the same as plain carbon steel, and has the following process requirements in some process. The stainless steel material can be carried by the non-metallic materials such as planks or rubber plates. Pipe cutting should not be cut with ordinary grinding wheel, it should be made of stainless steel special grinding wheel or plasma cutting. The inside of stainless steel tube and pipe fittings shall be protected by argon. Arc starting and arc, arc starting to use collect their welding, arc extinguishing should fill arc crater. The arc must be made within the groove, forbid arc in the pipeline, pipe parent metal surface and striking. If the holes and cracks are found in the arc and arc, the defects should be cleaned in time. Stainless steel pipes, pipe fittings and stainless steel pipes, pipe fittings and stainless steel pipes, pipe fittings connection, before backing welding butt joint welding tube and cavity should be filled with argon gas protection, to tungsten argon arc welding. The arc of multiple multi-layer welding and the arc of arc should be staggered. Continuous welding, stainless steel materials, the interlayer temperature less than 60 ℃. The welding seam of the pipe connecting the welder shall be treated with acid and passivation after welding. The water pressure test of the stainless steel pipe is required for water temperature and water quality, and the water temperature must not be less than 5 degrees Celsius. The chlorine ion content in water must not be greater than 25Pmm. Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

1. The atmospheric corrosion The corrosion resistance of the stainless steel pipe fitting is basically the amount of chloride in the atmosphere. Therefore, it is extremely important to be near the ocean or other chloride sources to corrode stainless steel pipe fitting parts. A certain amount of rain is important only when the chloride concentration of the steel surface ACTS. The rural environment of 1Cr13, 1Cr17 and austenitic stainless steel pipe fittings can be used for various purposes, and there will be no significant change in appearance. As a result, the stainless steel pipe fittings exposed in rural areas can be selected based on price, market availability, mechanical performance, manufacturing performance and appearance. Industry environment in the absence of chlorine pollution environment, 1 cr17 and austenite size stainless steel pipe fittings can work for a long time, basically no rust, could form dirt film on the surface, but when the film after clear, bright still maintained the original appearance. In an industrial environment of chloride, corrosion of stainless steel pipe fittings will be caused. Marine environment 1 cr13 and 1 cr17 stainless steel pipe fittings in the short term will form a thin film rust, but will not result in obvious changes in the size, shape stainless steel pipe fittings such as 1 cr17ni7 austenite, cr18ni9 1 and 0 cr18ni9, when exposed in ocean environment, may be some rust. Rust is usually shallow and can be easily cleared. The 0Cr17Ni12M02 contains molybdenum stainless steel pipe fittings which are basically corrosion-resistant in the Marine environment. In addition to atmospheric conditions, there are two other factors that affect the corrosion resistance of stainless steel pipe fittings. It is the surface state and the manufacturing process. The machining level affects the corrosion resistance of the stainless steel pipe fitting in the environment of chloride. Matte surfaces are very sensitive to corrosion. The normal surface of industrial processing is less sensitive to corrosion. Surface precision is also affected by the removal of dirt and rust. It is easy to remove dirt and rust from the surface of highly refined processing, but it is difficult to remove from the surface. For matte surfaces, if you want to maintain the original surface, you need to clean up a lot. 2. The fresh water Fresh water can be defined as water from rivers, lakes, ponds or Wells, regardless of acidity, salt or salt. The corrosion of fresh water is affected by the pH, oxygen content and scale of the water. Scale (hard) water. The corrosion is mainly determined by the amount and type of scaling of the metal surface. The formation of this scale is the presence of minerals and temperature. Non-fouling (soft) water is generally more corrosive than hard water. It can be reduced by increasing pH or by reducing oxygen content. 1Cr13 stainless steel pipe fitting is significantly more resistant to fresh water than carbon steel, and has excellent characteristics in fresh water. This type of steel is widely used for such purposes as the need for high strength and corrosion-resistant docks and DAMS. However, it should be considered in some cases. 1Cr13 May be sensitive to moderate erosion in fresh water, but point erosion can be avoided by cathodic protection methods. The 1Cr17 and austenitic stainless steel pipe fittings are almost completely resistant to freshwater corrosion at room temperature (ambient temperature). 3, Acidic water Acidic water is a contaminated natural water that is leached from ore and coal, which is much more corrosive than natural fresh water. , because the water contained in the sulfide leaching of ore and coal, acidic water usually contains a large number of free sulfuric acid, in addition, the water contains a large number of ferric sulfate, has very big effect to corrosion of carbon steel. Carbon steel, which is affected by acidic water, is usually quickly corroded. The results of experiments using the various materials used by acidic river water indicate that the austenitic stainless steel pipe fitting has high corrosion resistance in this environment. Austenite size stainless steel pipe fittings in fresh water and acid water has excellent corrosion resistance, especially its corrosion film on the heat conduction block is small, so widely used stainless steel pipe fittings pipe in the heat exchange purposes. 4, Salt water The corrosive characteristics of salt-water are often seen in the form of pitting. In the case of stainless steel pipe fittings, it is largely due to the partial destruction of the passive film with the corrosive effect of salt water. The other reason for the corrosion of these steel is that they are attached to the stainless steel pipe fittings and other seawater organic materials can form the strong differential batteries. Once formed, these cells are very active and cause a lot of corrosion and pitting. In the case of high salt water, such as pump impeller, the corrosion of austenitic stainless steel pipe fitting is usually very small. In the case of the condenser with stainless steel pipe fitting, the water flow rate is greater than 1.5m/s, so that the seawater organic and other solids are the least concentrated in the pipe. The structure of stainless steel pipe fittings for the treatment of saline water is best designed to reduce the gap and use thick wall parts. 5. Soil Metals embedded in the soil, depending on the weather and other factors, are at any time in a complex state of flux. In practice, the austenitic stainless steel pipe fittings have excellent properties for most soil corrosion, while 1Cr13 and 1Cr17 have some erosion in many soils. The 0Cr17Ni12Mo0 stainless steel pipe fitting is completely resistant to corrosion in all soil experiments. 6. Nitric acid The stainless steel pipe fitting and austenitic stainless steel pipe fittings and austenitic stainless steel pipe fittings have excellent corrosion resistance. 1Cr17 stainless steel pipe fitting is widely used in the processing equipment of nitric acid plant. However, since 0Cr18Ni9 usually has good forming performance and welding performance, it has replaced 1Cr17 stainless steel pipe fitting in large quantities in the above use. The corrosion resistance of other austenitic stainless steel pipe fittings is similar to that of 0Cr18Ni9. The stainless steel pipe fitting is usually slightly more corrosive than 0Cr18Ni9, and the higher temperature and concentration have a greater detrimental effect on it. If improper heat treatment of steel, hot nitric acid will make austenitic stainless steel and iron grain size fitting produce intercrystalline corrosion, therefore, can use the appropriate heat treatment to prevent this type of corrosion, or use this type of corrosion resistant stainless steel pipe fittings. 7. Sulfuric acid Standard stainless steel pipe fitting plates are rarely used in acid solutions because they can be used in a narrow range. At room temperature, the type 0Cr17Ni12Mo2 stainless steel pipe fitting (the standard number for the most sulfuric acid corrosion) is less than 15% in sulfuric acid concentration. Or more than 85% resistant to corrosion. However, at higher concentrations, carbon steel is commonly used. The martensitic and iron body shape stainless steel pipe fittings are generally resistant to sulfuric acid solutions. As in the case of nitric acid, if the stainless steel pipe fitting is not properly treated, sulphuric acid can cause corrosion. For welding structures that do not undergo heat treatment after welding, use the low carbon number 00Cr19Ni10 or 00Cr17Ni14M02, or the stabilized number 0Cr18Ni11Ti or 0Cr18Ni11Nb stainless steel pipe fittings. 8. Phosphate Austenitic stainless steel pipe fittings have good corrosion resistance to phosphate and are widely used in the production and processing equipment of phosphoric acid. At temperatures up to 107 ℃ under the condition of various concentrations, its effective corrosion resistance. Under the condition of the highest temperature about 95 ℃, with 0 cr17ni12m02 stainless steel pipe fittings of equipment is a good way to deal with (phosphoric acid) “more than 100% H3p04). It should be noted that fluoride or chloride salts are sometimes found in phosphoric acid produced by wet process. The presence of these halogens in acids may have detrimental effects on corrosion resistance of stainless steel pipe fittings. The corrosion resistance of the martensitic and iron stainless steel pipe fitting parts is significantly worse than the austenitic stainless steel pipe fitting, so it is not commonly used in this acid. 9. Hydrochloric acid Even at room temperature, the solution of hydrochloric acid at various concentrations quickly corrodes the stainless steel pipe fittings. stainless steel pipe fitting is not possible in this acid. 10. Other inorganic acids Austenite size stainless steel pipe fittings in almost all kinds of concentration and temperature are generally has good resistance to boric acid, carbonic acid, chlorate and the performance of the chromic acid corrosion, 100% except the chlorate. The corrosion resistance of 1Cr13 and 1Cr17 stainless steel pipe fittings to chromic acid is significantly inferior to austenitic stainless steel pipe fitting, but it has the performance of relatively good boric acid and carbonic acid corrosion. 11, acetic acid, Austenite size stainless steel pipe fittings general has excellent resistance to acid corrosion performance, grain size and martensite and iron the purpose of the stainless steel pipe fittings for most acetic acid corrosion resistance is not appropriate. Austenite size stainless steel pipe fittings at room temperature can resist the corrosion of various concentrations of acetic acid, at higher temperature, 0 cr17ni12mo2 and 0 cr19ni13m03 than other austenite size acetic acid corrosion resistance of stainless steel pipe fittings have been better. 12, formic acid At room temperature, any austenitic stainless steel pipe fittings can be treated completely with formic acid. However, when it is hot, it can quickly corrode stainless steel pipe fittings that do not contain molybdenum, and therefore require the use of 0Cr17Ni12M02 and 0Cr19Ni13M03. At various temperatures, the acid will soon corrode the martensite and the stainless steel pipe fitting. 13, oxalic acid In general, stainless steel pipe fitting has good resistance to oxalic acid corrosion at least 50% at room temperature and maximum concentration. At higher temperatures, however, the oxalate solution, as at room temperature and concentration at 100%, will corrode all stainless steel pipe fittings. 14, lactic acid 0 cr18ni9 stainless steel pipe fittings in the highest temperature of about 38, < / SPAN > when ℃ can be used for lactic acid storage devices. At higher temperatures, non-molybdenum austenitic stainless steel pipe fitting is a bit denuded, so the priority is 0Cr17Ni12M02 and 0Cr19Ni13M03. Martensitic stainless steel pipe fittings are generally less resistant to lactic acid corrosion. 15, alkali stainless steel pipe fittings usually have a good performance against weak alkaline corrosion, such as ammonium hydroxide. For strong base, such as sodium hydroxide and potassium hydroxide, the highest temperature is about 105 ℃, the concentration of about 50%, the highest austenite size stainless steel pipe fittings with good corrosion resistance, high temperature and the concentration of corrosion rate may become significant. When the temperature is above the normal pressure boiling point (and the lower temperature, near 50%), the stainless steel pipe fitting of the austenitic body will appear in the stress corrosion crack. 16,, Salt acid Besides the halide solution under certain conditions, stainless steel pipe fittings in general has excellent resistance to corrosion performance, hydrochloric acid solution for acid salt, corrosion resistance of stainless steel pipe fitting in a certain extent inevitably affected by salt water solution formed by the influence of the special acid. The stainless steel pipe fitting parts (0Cr17Ni12Mo2 and 0Cr19Ni13Mo3) are usually better than other stainless steel pipe fittings in the case of a higher temperature acidic solution. In stainless steel pipe fittings used in halide solution, especially in chloride solution, should take into account the average corrosion rate is low, but the pitting corrosion and stress corrosion crack (or) under certain conditions can also be produced. Although there are many in chloride using stainless steel pipe fittings obtain excellent effect (such as food processing equipment and under the condition of relatively low temperature flowing seawater) but must consider the different purposes. The occurrence of spot or stress corrosion cracks depends on many factors, such as environment and equipment design and operation. Source: China Pipe Fittings Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel pipe has become the United States nearly 25 years to build the city wastewater treatment plant (WWTP) standard timber. Since the late 1960s, there have been more than 1,600 municipal wastewater treatment plants in the United States that use stainless steel aeration pipes, digestion tank gas pipelines and sludge pipelines, as well as stainless steel mobile bridges, valves, ponds, bolts, handrails and Other equipment. The initial selection of stainless steel instead of galvanized and painted carbon steel is to reduce maintenance and replacement costs, these materials repair and replacement costs are higher because of their poor corrosion resistance. Low-carbon steel grades 304L and 316L are used for welded construction. The purpose of using these low-carbon steels is to resist corrosion after corrosion without heat treatment. Higher carbon content can increase the strength of the steel, mainly for the stem and pump shaft, these components do not need welding, high strength can make the design optimization. Molybdenum-containing stainless steel is better resistant to localized corrosion, preferably in a more aggressive environment or in order to prevent unexpected accidents that may occur at any time. The corresponding steel products have corrosion resistance and similar mechanical properties. 304 / 304L and 316 / 316L stainless steel are the main materials of sieve, grit chamber, overflow weir, bolts, mobile bridge, aeration tank, digestion tank and sludge pipeline in urban wastewater treatment equipment. In the past 20 years , According to the International Nickel company conducted field tests, these materials have become the standard construction materials. 304 and 316 stainless steel weight loss corrosion rate <0.1 mil / year. Corrosion rate <0.1 mil / year indicates that the useful life of this material is expected for more than 20 years. These very low corrosion rates mean that there is no need to leave a "corrosion margin" on the wall thickness when designing stainless steel equipment, but corrosion margins must be left for carbon and ductile iron. So the use of stainless steel in terms of weight / material can save much more. Service performance of stainless steel Experiments and experience show that 304 and 316 stainless steel has the following advantages: (1) resistance to atmospheric corrosion of steel to add chromium to improve the corrosion resistance. The amount of chromium required to make the stainless steel “no rust” may vary depending on the weight loss of the steel content. Chromium content greater than and equal to 12.5% of the steel in the marine atmosphere exposed to 25 years after the weight loss is quite small. These “pure chrome” stainless steels (ferrite and martensite) and the surface layer have a layer of corrosion, which is not suitable for use in many atmospheric environments where the appearance is particularly important. In contrast, nickel and nickel containing 8% to 10% of the austenitic steel grades 304 and 316 are more resistant to corrosion and are exposed to the atmosphere for many years. The H2S gas produced in the digestion tank penetrates into many parts of the wastewater treatment plant, accelerating corrosion of copper alloys, aluminum and carbon steels. In humid H2S, 304 and 316 stainless steel corrosion rate <0.1 mil / year (<0.0025mm / year). This corrosion rate is negligible. 304L stainless steel is the digestive tank gas pipeline standard material, and the use of good results. Although people do not want to expose the steel to wet chlorine, but in the chlorine storage area near the well ventilated limited position, the appearance of the pipe did find some general pitting. 304L and 316L stainless steel in the wet chlorine accumulation and condensation of the non-ventilated atmosphere is easy to rust and the occurrence of general pitting. Proper ventilation can eliminate these phenomena, you can also regularly spray the surface of stainless steel, can rust and pitting can be reduced to a minimum. (2) Chlorine-Ozone Stainless steel is usually resistant to the general concentration of chlorine gas in the wastewater treatment equipment. According to 1010 carbon steel, cast iron, 304 and 316 stainless steel samples exposed to chlorine in a certain residual chlorine concentration of fresh water exposed data, 304 and 316L in the residual chlorine content of up to 2ppm of well water corrosion resistance is good, and Carbon steel and cast iron corrosion rate is twice as high. If the continuous exposure to 3 ~ 5ppm residual chlorine, the measured data show that 304 / 304L prone to crevice corrosion, insurance should use 316L, stainless steel is not suitable for chlorine spray system, where the chlorine content of up to 50 to hundreds of ppm. Ozone is an increasingly popular oxidant substitute that can be used alone or in combination with chlorine. Although the initial use of ozone generator 316L selection without the use of 304L background and lack of data, but 316L has become the best material for the manufacture of ozone generator. (3) Other chemical additives Ferrous sulfate is a chemical additive that is often added to wastewater treatment plants: De Renzo says 304 and 316 stainless steel samples are in ferrous sulfate solution containing sulfuric acid (waste acid solution) with pH value of 1 to 2.5 Corrosion resistance is very good, corrosion rate of less than 0.8 mil / year (<0.02mm / year). In the wastewater treatment plant, there is generally no sulfuric acid, therefore, stainless steel in the acid-free ferrous sulfate corrosion rate can be ignored. Ferric chloride is sometimes used in the conditioning tank to flocculate, the sludge is further concentrated and dehydrated in the conditioning tank, and then burned and drained. The 304 and 316 samples placed on the activated sludge position 6 have both pitting and crevice corrosion in the presence of ferric chloride content of 250 to 300 ppm. 316 stainless steel Corrosion resistance to ferric chloride slightly better than 304 stainless steel, can be used as a more conservative choice for ferric chloride injection point after the higher content of ferric chloride. Although the test data is not ideal, however, 304 stainless steel pipe is generally used for conveying the effluent after treatment. (4) microbial corrosion (MIC) standard stainless steel in the stagnant and slow flow of water, the weld and weld around sometimes prone to microbial corrosion. The presence of microbial corrosion on a frame made of 409 (11% chrome) stainless steel in a rotary bio-compression device (RBC’s) tested in a wastewater treatment plant is an example. Microorganisms are roughly stacked at the welds of the frame. Rotary bio-compression device stainless steel frame to 2 rev / min speed in the sludge when the time out for the microbial corrosion provides the ideal environment. There is little microbial corrosion in other parts of the wastewater treatment plant. Cost comparison Stainless steel design for light components and piping systems has been very cost effective. Although the initial investment cost of stainless steel may be higher than other materials, but its long life, the total maintenance costs are low, the total life expectancy reduced costs. The European Stainless Steel Development and Information Group (EUROINOX) has completed a European project for a wastewater treatment plant in Italy. Although the initial installation cost of stainless steel is more than 25% higher than that of carbon steel, only the life cycle cost of carbon Steel flat. This analysis includes capital costs and maintenance costs, and the choice of stainless steel for design, saving weight using a conservative estimate of 10%. Stainless steel devices include mechanical guards, mobile bridges and handrails, these parts are commonly used galvanized steel. 304L and 316L stainless steel pipes have been very successful for use in pipes and other uses in wastewater treatment plants. The high design performance and low corrosion rate of stainless steel allow the use of lightweight construction. Good cleaning and maintenance of the factory will further improve the excellent performance of stainless steel. Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

1. Application of stainless steel in construction industry In recent years, the application of stainless steel as a building material is becoming increasingly widespread. The use of a wide range of reasons has a wide range of reasons, including a better understanding of the material, trying to update some of the design, imagine the production of a durable and no maintenance of structural materials. In the early days, the use of stainless steel for construction was limited to certain occasions, where architects were looking for a new material with special effects in the absence of proper material in the past. In fact, many such occasions, stainless steel has been used for a long time and its effect has been a long period of continuous erosion of the role of stainless steel, so that manufacturers believe that stainless steel materials for outdoor applications even in high corrosive gases under the conditions of corrosion. Because stainless steel is durable and almost no need to maintain the surface of these two characteristics, to make people more than ever before more attention to its application. Most of the price of building materials in a certain proportion of rapid rise, and there are many materials prices and far more than stainless steel. The cost of maintaining and maintaining the structure of the building inside and outside is even more soaring. Today’s architects must seriously consider the whole situation of the building. If the building needs to be replaced or repaired for many years, then the architect’s design is a failure. In recent years, the walls of the swimming pool have been made of stainless steel. The main materials used for a long time need to be repaired and painted annually, especially in the northern region. The use of carbon steel and coated swimming pools also requires a large area of scrubbing and brushing each year, both of which add to the pool Considerable use of expenses. When the pool is made of stainless steel (304, 2B finish) to do the side wall, scrub is very simple, just water and soap can be quickly washed. Now the swimming pool is often used stainless steel tank wall and mixed soil bottom, the bottom of the concrete is mainly for non-slip. Some buildings of the wall with 304, 8 mirror polished stainless steel as a material. The interconnected stainless steel plates are polished and colored to polish the walls with consistent color wither and reflective properties. In order to prevent grease, a large area of stainless steel plate exposed part (velvet feet) installed in the galvanized sheet and the compression plate composed of thick sandwich. Polished stainless steel plate with epoxy resin as binder and galvanized steel plate connected fixed. Made of dry stainless steel can be very soft performance, so that it may be used as a roof cover material. It is because this material is easy to shape, durable and beautiful, so many architects choose stainless steel not only as a protective layer, but as an integral part of the overall design. Some buildings (indoor skating rinks) are made of stainless steel in the construction of the roof of the Yongping overlapping layer, not only to make the building from the design point of view nice, but also because of the reflective surface of stainless steel, so that the indoor ice season to extend the rabbit Bear unreasonable investment. For some special structures, often due to the application of stainless steel to make many problems resolved. For example, there is a garage, the design requirements of the parking garage on the parked vehicles not only have a protective effect and the exhaust gas has a good ventilation; but also to a certain degree of sunlight into the garage, the selection is durable and no maintenance. To meet the above requirements, the designer selected 6 * 10in (15 * 25cm) 201 stainless steel grating, the grid will be fixed on the vertical column, so that the internal and external staggered caused by overlapping layout.To enhance the effect of building facilities, staggered outer grid On the use of floating surface finish, the outer row of column grid using ordinary 2B finish, all inside the grid are 2D light exposure. This change in the pattern of the garage has a vivid appearance. For a building roof structure, its life and appearance should be the same attention. At the airport’s restaurant, in order to make the roof beautiful, exhaust fans are covered with stainless steel plate. In the choice of cover material, but also stressed the non-reflective material. The selected materials are 304 stainless steel, rough polishing, low reflectivity, 6 finish. For the selection of light to pay special attention to the special due to the issue of glare, to prevent the pilot to reach the destination landing when the line of sight. Office buildings inside and outside the building to the structure are used in stainless steel. Its architectural measures use stainless steel as a curtain wall. The columns at the entrance of the building are covered with stainless steel plates, and all the windows of the building are cleaned with stainless steel. The ceilings above the office building lounge are made of stainless steel plates with relief. Use the male and female mold to punch the embossed part on the stainless steel sheet. Stainless steel is not only long life, but also the production of captive convex to the structure of a good material, which can enhance the shape of the building beauty, it is often the main sign of the square. Another example of stainless steel as a main material for outdoor end architecture is the famous arch that stands on the river. Stainless steel material can be arbitrarily selected. It has a variety of different strength-to-weight ratios to suit all types of building structural requirements. In addition, different grades of surface finish also provide a range of options for a variety of different construction facilities to meet the actual needs. The architect’s bold idea will make the application of stainless steel in the construction industry increasingly widespread. 2. Application of stainless steel in marine installations A variety of different types of stainless steel are increasingly widely and successfully used in a variety of marine environments. It must be pointed out that the long-term corrosion of stainless steel in seawater requires complex anti-corrosion engineering technology and substantial investment. Austenitic and martensitic stainless steels have long been used for superheater pipelines and turbine blades on navigational power units. It is not easy to maintain a low chloride content in these devices because there is no difference between the application of navigational power plants and the basic principles of general power generation devices. Stainless steel is also being used for large-capacity chemical containers on ocean-going merchant ships, and its use is in some respects different from the use of terrestrial chemical plants. Most stainless steel grades are satisfactory in marine applications, but different grades are sensitive to stress corrosion cracking. Model 401 as the representative of the martensitic steel and 430 as the representative of the ferrite steel, in the ocean conditions, within a few months will rust. This uniform rust can be removed by mechanical grinding. The more popular stainless steel is austenitic stainless steel because of its strong resistance to corrosion (except for stress corrosion cracking). With the passage of time, austenitic stainless steel will also be black. This blackening can also be removed by grinding due to aesthetic or other reasons. Stainless steel in the water rarely produce uniform rust candle, so in actual use can not worry. Propeller Marine tugs and other vessels on the propeller can be made of cast stainless steel CF-8 (quite dry 304 stainless steel). When the vessel is not sailing, from the propeller spindle through the bearing to the hull, constitute a conductive metal circuit. Equivalent to 410 stainless steel casting propeller is also often used, and in other areas are widely used, such as for icebreakers and so on. The development of modern stainless steel technology, has begun to use compound phase austenitic – ferritic stainless steel 20Cr-8Ni-3.5Mo to cast large-scale thrust vessel (weighing 3000kg). Often working in the port of the vessel, particularly vulnerable to the surface of the logs or other floating body to accelerate the damage of the propeller. Therefore, the use of austenitic stainless steel propeller can be straightened or welded by the way to be repaired, which is a matter worthy of attention on the selection. Pump It has long been observed that the centrifugal pump in the sea under the conditions of work, such as the use of stainless steel components, can show a certain degree of reliability. In the flow of water, the use of CF-8M casting stainless steel impeller (its composition is equivalent to 316 stainless steel) and 316 stainless steel as the spindle, can not any problem. When the pump stops working, crevice corrosion and point corrosion is likely to be a serious problem. However, if you use a more lively and rusty cast iron to make a considerable wall thickness of the pump box, the cast iron in the downtime can play a cathodic protection. When the pump work, the cast iron box under the protection of the cathode will be able to make the next rust steel, but the flow of water to be cathodic protection. In addition, long-term work of the pump may be due to the use of alternating, both when the water replaced with fresh water and play a protective role. Bulk containers Stainless steel has been used as a bag container for shipping in liquefied natural gas (LNG), chemicals, beverages and so on. Cargo in the LNG container used to use 304L stainless steel, its purpose is not to corrosion-resistant but taking into account the mechanical properties at low temperatures. For marine chemical containers, the purpose of using stainless steel is mainly to take into account its corrosion resistance, which is different from the storage and transportation of land chemicals. If the vessel belongs to a general irregular ship, the container carrying the chemical may also transport any item from acetic acid, bad pulp to xylene. Generally use 316L stainless steel for valves, cargo pumps, tubes, heating coils and containers themselves. The container may be made of integral stainless steel or coated with a carbon steel sheet with a 0.06 to 0.08 in. (1.5 to 2.0 mm) stainless steel plate. Before use, must be carefully checked whether the sheet is defective and thorough cleaning and passivation treatment. Experiments show that the equipment with chemicals allowed to rinse with seawater, but then bored with fresh water quickly. For any stainless steel heating device in the container, do not start to prevent stress corrosion cracking until the chloride has not been thoroughly washed off. The design of the chemical container shall not be taken into account for the risk of crevice corrosion due to the presence of seawater. If the design scheme is not intended to contain water, it is necessary to consider a cathodic protection system to control the development of crevice corrosion. In this case, the stainless steel container may produce difficult to remove the calcareous deposits, which is a matter worthy of attention. Heat exchanger Forced water cycle system cooler and power station steam condenser has been widely used austenitic stainless steel pipe, the latter of the inlet due to high pollution and should not use copper alloy material. The more popular material is 316 stainless steel. In the coastal and harbor areas, a large number of foreign agglomerates and sludge into the condenser ducts are particularly vulnerable to serious obstacles, which must be taken to eliminate them. A reasonable measure is to use the rubber ball through the pipeline, because the rubber ball can produce squeeze to clean up the pipe wall. When the flow rate of seawater is about 1m / s, it can prevent the marine organic debris from being inhaled, so as to protect the condenser from corrosion. Unlike other non-ferrous alloys, pipes made of stainless steel as the condenser are not subject to the maximum flow rate, but are related to the economic effect of the entire pump unit. Shaped ring Series-type electrical connectors and related O-ring positioning devices are widely used 304 and 316 stainless steel manufacturing, especially marine and military engineering. Using the above materials can be satisfied with the use of results. O-shaped seals can be cathodic protected by hull, aluminum or other factors. If there is no cathodic protection, the O-ring is very bad (some in a few weeks) will produce cracks and corns and cause serious failure. 3. Oil extraction, mining industry In recent years, oil extraction gradually from the land to the sea, offshore oil fields are more and more, and because the sea environment is relatively poor, the general pipe fittings can not meet their requirements. The superior performance of stainless steel pipe can meet the requirements of offshore oil field. Source: China Pipe Fittings Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

After rolling of stainless steel pipe fittings, it’s surface of the scale and the collective combined with strong, difficult to remove, if directly for pickling, the effect is not very good, so can be a pretreatment measures first, and then the oxidant, activator of mix acid cleaning can be more effective to remove oxide skin stainless steel. There are two kinds of pretreatment methods for stainless steel pipe fittings: alkali dip and shotblast. 1, alkali leaching Base leaching is the structure of a tube that is immersed in an alkaline molten salt or solution which changes the oxide skin. Base leaching can be classified as molten salt alkali and solution alkali leaching. Stainless steel surface intact by the molten salt leaching, acid pickling metal loss is relatively small, and can greatly shorten the pickling time, improve the efficiency of production, the molten salt to keep in high temperature condition, high energy consumption, molten salt leaching of another disadvantage is the need for specialized alkali trough, alkali bath temperature cycle is long, large energy consumption. Some manufacturers are not able to produce in a continuous production, and the solution base immersion process is chosen. The principle of solution alkalinity is the same as that of molten salt, but the temperature is lower than the boiling point of the solution, and the corresponding length is correspondingly. In alkaline aqueous solution of potassium permanganate (temperature is about 100 ℃) soaked although save energy, but the production efficiency is low, only as a supplementary means. 2, shot peening method Shot peening method is to use shot nine machines will pill grain accelerated to a certain speed, and spray at a certain Angle to the rotation of the surface of the pipe, under the impact of the pill grain, the surface of the steel to produce elastic deformation, scale almost no elastic deformation capacity, so the scale is broken and loose, fall off. General carbon steel and low alloy steel pipe scale thicker, the weaker with substrate with shot peening method of scale removal can be clean, but the stainless steel pipe scale thin, dense, adhesive strength with substrate, it is difficult to clear the scale by shot peening method is clean, can only as a pretreatment before pickling means much for annealing martensite steel, ferritic steel, and do not allow the alkali pretreatment of immersion precipitation hardening stainless steel pipe fittings. The pellet is chosen to have a certain hardness, the steel pellet that is resistant to fracture. The material, diameter, the speed of the shot and the amount of pills will affect the surface of the cleaned pipe. The shotblast method is pided into two kinds: single root expansion shot blasting and disc spray shot, and the production efficiency is considered, and the scale production is appropriate to choose the disc type. The advantages of shotblasting method: high efficiency, energy saving, small occupation area, no pollution environment, suitable for mass production. The drawback is that it is a one-off investment. Source: China Pipe Fitting Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel head in the heating and cooling process, the stainless steel head due to the surface and the heart of the cooling rate and time inconsistency, the formation of temperature difference, it will lead to volume expansion and shrinkage uneven stress, that is, thermal stress. Under the action of thermal stress, because the surface temperature is lower than the heart, the contraction is greater than the heart and the heart of the stretch, when the end of the cooling, due to the final cooling volume shrinkage can not be free to make the surface by the heart Pull up. That is, under the action of thermal stress, the final surface of the workpiece pressure and the heart of the stretch. This phenomenon is affected by cooling rate, material composition and heat treatment process and other factors. When the cooling rate is faster, the higher the carbon content and the alloy composition, the greater the uneven plastic deformation produced by the thermal stress during the cooling process, and the greater the residual stress formed. On the other hand, the steel in the heat treatment process due to changes in the organization that austenite to martensite transformation, due to the increase in specific volume will be accompanied by the expansion of the workpiece volume, the workpiece has changed the various parts, resulting in volume growth is inconsistent and produce tissue stress. The ultimate result of the stress change of the stainless steel head is the tensile stress of the surface layer, the compressive stress of the heart, and the opposite of the thermal stress. The size of the tissue stress is related to the cooling rate, shape, chemical composition of the workpiece in the martensitic transformation zone. But the thermal stress in the organization before the transformation has been produced before the stainless steel head, and tissue stress is generated in the process of transformation, in the whole cooling process, the thermal stress and the combined effect of tissue stress is the actual existence of the workpiece The stress. The combined effect of these two stresses is very complex and is influenced by many factors such as composition, shape, heat treatment and so on. There are only two types of developmental processes, namely, thermal stress and tissue stress, the opposite direction of action when the two offset, the role of the same direction when the two are superimposed on each other. Whether it is offset each other or overlap each other, the two stresses should have a dominant factor, the role of thermal stress when the dominant position is the workpiece heart tension, the surface pressure. The effect of tissue stress on the dominant position is that the workpiece is pressed against the surface of the workpiece. Source: China Head Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel bend is also a type of stainless steel tube, which is mainly to distinguish the shape of the pipe from the shape of the pipe, including the u-tube, the j-type, the s-type pipe, and 90 degree snake-head bend. The bending of the bent tube is pided into hot and cold, which is mainly used for the hard and variable type of steel pipe, such as the heat of the carbon steel pipe. The cold stewed bend is mainly used for the relatively hard material of the galvanized pipe. When it’s cold, it goes without saying, and it’s just a matter of turning the bending machine into a bend and turning it into a bend. The process of simmering the heat is much more complex, mainly pided into these steps. A steel pipe material, the incoming inspection, including chemical element spectrum examination, the tensile strength and impact strength, hardness of materials (can measure brinell and vickers hardness, hardness, etc.) on the Richter scale, learn about its further processing. Second, the pipeline of blanking, according to the required degree of bent pipe is calculated into straight pipe length blanking, and blanking must have a certain margin, to ensure the machining allowance. Three, roasted bend, through the intermediate frequency electric heater heat to simmer roasted bend segment to need the number of degrees, again through the simmer bending machine set degree, slowly simmer bending pipe, finally complete the whole segment reserved after simmer bending bends straight pipe length cutting pipe bending. To get into the process of the next bend pipe, through the lathe, turn the pipe into a slope of about 40 degrees, and remain blunt. Processing is completed, is to examine the bent pipe size, meet the requirements into the bent pipe heat treatment, common (steel tube) is heated to above 500 degrees Celsius, constant temperature and a half hours, then cool air condition. Then, the quality of production is ensured by magnetic particle testing and ultrasonic testing. Material: Carbon steel: ASTM/ASME A234 WPB, WPC Alloy: ASTM/ASME A234 WP 1-wp 12-wp 11-wp 1-wp 5-wp91-wp911, 15mo315crmov, 35CrMoV Stainless steel: ASTM/ASME A403 WP 304-304l-304l-304n-304n ASTM/ASME A403 WP 316-316l-316316316316316n-316ti ASTM/ASME A403 WP 321-321H ASTM/ASME A403 WP 347-347H Low temperature steel: ASTM/ASME A402 WPL3 – WPL 6 High performance steel: ASTM/ASME A860 WPHY 42-462-60-65-70 Cast steel, alloy steel, stainless steel, copper, aluminum alloy, plastic, argon and drain, PVC, PPR, RFPP (enhanced polypropylene) etc. It can be pided into two categories: pushing, pressing, forging, casting and so on. The standards of manufacturing are pided into the national standard, the electric standard, the ship standard, the scale of the scale, the water standard, the standard, the German, the Japanese, the Russian standard, etc. According to its curvature radius, it can be pided into long radius bend and short radius bend. The radius of a long radius means that the radius of the curvature of the tube is equal to 1.5 times the diameter of the pipe, which is R = 1.5 D. A short radius bend means that the radius of the curvature is equal to the outer diameter of the pipe, which is R = 1.0 D. (D is the diameter of the bend, R is the radius of curvature). If you follow the stress level: there are about a dozen or so, and the standard for the American pipe is the same: Sch5s, Sch10s, Sch10, Sch20, Sch30, Sch40s, STD, Sch40, Sch60, schaft, XS. Sch80, SCH100, Sch120, Sch140, Sch160, XXS; The most commonly used are STDS and XS. Besides the above said is only the small diameter pipe bending, if there are any large diameter pipe bending, because there is no such a large diameter seamless pipe, also USES the steel plate round tube of legal system, which will meet the welding, welding according to the different welding materials used in the pipe is also differentiated, after been in straight seam pipe welding is bend pipe into roasted the process. Source: China Stainless Steel Bend Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Causes of surface corrosion of stainless steel pipes Stainless steel pipe can also be called acid-proof stainless steel pipe, is mainly composed of two pieces of stainless steel pipe and acid steel, stainless steel pipe can be either atmospheric corrosion resistance, resistance to chemical corrosion medium. It is commonly believed that when the chromium content in the pipe is greater than 12%, it is characterized by the stainless steel pipe. Stainless steel pipe according to the microstructure after heat treatment and can be pided into five kinds, namely ferritic stainless steel pipe, martensite stainless steel pipe, austenitic stainless steel pipe, austenitic, ferritic stainless steel pipe and precipitated carbide stainless steel pipe. Stainless steel pipe products in the production process there will always be surface damage, defects, and some influence on the surface of the material, such as dust, iron powder, hot temper color and other oxidation layer, rusty spot, grinding burrs, arc welding spot, welding spatter, welding flux, welding defects, oil and grease, residual adhesive and paint, chalk and marker and printing, and so on. Most of it is due to ignoring these harmful effects or not doing well. But these factors can damage the protective coating, which is corroded when the protective membrane is damaged and thinned. Also, corrosion usually does not involve the entire surface of the stainless steel pipe, only around the defect or around it. This kind of local corrosion is usually a pitting or crevice corrosion, which can be corroded in depth and breadth without affecting most surfaces. Here are the causes of these problems. dust The stainless steel pipes are often in dust in the production process, and the dust in these air is constantly falling on the surface of the stainless steel pipe. The dust can be washed away by water or alkaline solution. But if there is a adhesion dust, use a water cannon to clean it up. An iron powder or embedded iron On the surface of the stainless steel pipe, the free iron will rust and corrode the stainless steel pipe. So be sure to get rid of it. The powder is usually cleared with the dust. Some of the adhesion is stronger and must be treated with embedded iron. Iron dust in addition to iron, stainless steel pipe surface source of many, including using ordinary carbon steel wire brush to clean up and used in carbon steel, low alloy steel or cast iron pieces of the used sand, glass beads or other abrasive shot peening treatment, or in the vicinity of a stainless steel pipe parts and equipment of the previously mentioned the grinding stainless steel pipe products. Next material or hanging if not stainless steel pipe protection measures, in the process of wire rope, sling and iron on the surface of the table also easier to embed or defiled with stainless steel pipe surface. The scratch In order to prevent the lubricant process or product or dirt storing up, be sure to scratches and other rough surface of stainless steel pipe to do mechanical cleaning, make it smooth recovery. Heat reheat and other oxidation layers In the process of welding or grinding, stainless steel pipe in the air will be heated to a certain degree of high temperature and then weld on both sides, and under the surface and bottom of the weld will appear chromium oxide thermal heat tint. The heat return is thinner than the oxide film and is visible. This color is determined by the thickness of the color, which will present a rainbow, blue, purple and light yellow and brown color. Thicker oxide is usually black. This is because of prolonged periods of high temperatures. When any type of oxidation layer occurs, the chromium in the surface of the stainless steel pipe decreases, resulting in less corrosion resistance in the corresponding area. In this case, not only to remove the heat and other oxidation layers, but also to clean up the poor chrome-metal layer below them. Rusty spot Sometimes the rust on the stainless steel pipe or equipment indicates that the surface of the pipe is seriously polluted. The equipment must be removed before it is put into use, and the cleaned surface should be tested by iron test and water test. Rough grinding and machining Grinding and machining can lead to rough surface of stainless steel pipe, which can be used as a groove, overlap and burr. And each type of defect can also lead to the metal surface damage to a certain depth, so that the damage of the surface of the stainless steel pipe can’t through pickling, electrolytic polishing and shot peening method. Rough surface of the stainless steel pipe will become the birthplace of erosion and deposition products, heavy cleaning before welding defects or remove excess weld, now can’t use coarse grinding grinding, applying fine abrasive grinding. Weld arc specks Welders can cause surface roughness when they draw arc on metal surface. The protective membrane is damaged, leaving a potential source of corrosion. The welder shall draw the arc of the weld that has been welded or the side of the weld joint. The arc trace is then fused into the weld. Weld spatter Welds have a lot to do with welding technology. If the gas is shielded from tungsten electrode welding or inert gas protection tungsten electrode welding is not splattered. However, if the welding parameters are not used properly, a large amount of splash will be formed if the welding parameters are not used when the welding process is shielded by the gas shielded metal arc welding and arc welding of the solder core. You must adjust the parameters at this point. If you want to solve the problem of welding spatter, apply the spray to each side of the joint before welding, which will eliminate the adhesion of the splash. After welding, it is easy to clean up the spray and all kinds of splashes without damaging the surface of the stainless steel pipe or just minor damage. flux Use flux for welding process with manual welding, flux core arc welding and submerged arc welding, the welding process will leave fine flux grains in the surface of stainless steel pipe, the general cleaning method is not clear. These particles will be the source of corrosion for cracks, so be sure to remove the residual flux by mechanical cleaning. Weld defects Welding defects such as biting, unsoldered, denser pores and cracks not only reduce the fastness of the joints, but also become the source of corrosion. When you do this, you will also have solid particles. A good way to do this is by resoldering or resoldering. Source: China Steel Pipes Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel angle bar is a kind of widely used stainless steel section, which has the characteristics of structural stability, corrosion resistance, strong resistance to deformation and stability of chemical properties. It has an incomparable advantage over other metal materials. Name definition of stainless steel angle bar Stainless steel Angle is commonly referred to stainless steel material, the long strip of steel that is rectangular on each side. The length of the bar is pided into equal sides stainless steel angles and stainless steel angles. The two sides are equal to the stainless steel angles. The stainless steel angle bar is made of stainless steel Stainless steel angles can be classified according to the material, common for markov size stainless steel, iron, stainless steel, duplex stainless steel, austenite stainless steel and precipitation hardening stainless steel, and so on. Austenitic stainless steel The output and quantity of this kind of material occupies the mainstream position of the product, accounting for 70.1 percent of the total stainless steel. It’s a very important category in stainless steel. The austenitic stainless steel can be pided into two types: chromium nickel steel and ferrochrome. The former is an austenitic element with nickel, which is the main body of austenitic steel, which takes into account the cost of production, the latter is a nickel steel which is used as a nickel for manganese and nitrogen instead of expensive nickel. Good corrosion resistance of austenitic steel, good integrated mechanical properties and technical performance, but weak strength and hardness. Iron is stainless steel Iron-clad stainless steel contains 31-30%, which is non-nickel and is a nickel steel, which is mainly made of ferrite in the state of use. Iron grain size stainless steel has higher strength and lower cold hardening tendency, resistance to chloride stress corrosion, pit corrosion, crevice corrosion and local corrosion performance is good, but is sensitive to intergranular corrosion, poor toughness at low temperature. Duplex stainless steel Traditional thought, on the austenitic matrix is more than 15% of the ferrite, on the other hand, there is more than 15% of the ferrite matrix we can call austenitic austenitic + ferrite duplex stainless steel. Duplex stainless steel has the advantages of austenitic steel and ferritic steel. These are common materials for making stainless steel angles. In addition, the above materials are also widely used in other forms of form, plates, pipes and so on. Description of common stainless steel angle bar Size notation When we see this statement, “30 by 30 * 3”, which means that the edge width is 30 mm, the side thickness is 3mm, the stainless steel angle bar. This is the number of millimeters in the width of the side width by side. Figure 2 The model is the width of a centimeter, such as Angle 3 #. Model cannot express the same edge thickness in different circumstance of product information, and therefore the buyer and the seller at the time of custom contract, still need to fill in the width, and thickness of the stainless steel Angle bar size is complete, rather than separate with that model, in order to avoid ambiguity, caused the dispute. At present, the common domestic stainless steel angle bar specification is 2 to 20, with the centimeter number of the side length is number, the same number of angle bar is about 2 to 7 different sides thick. The import stainless steel Angle indicates the actual size and thickness of each side and the relevant standard. Generally large stainless steel Angle bar length more than 12.5 cm, 12.5 cm, 5 cm as the medium between the stainless steel Angle, less than 5 cm length for small stainless steel angle. The delivery length of stainless steel angle bar In addition to the thickness of the stainless steel, the product is also required to order the product according to the length. To meet the needs of different application scenarios. Stainless steel bar length, length of delivery points two times ruler, domestic stainless steel Angle iron scale range according to different size specifications have 3 to 9 m, 4 m, 4-12-19 m, 6 – m four range. The length of Japanese stainless steel angle bar is 6-15m. The section height of stainless steel angle bar is calculated by the long side width of stainless steel angle bar. Stainless steel angle bar appearance quality requirement Stainless steel Angle should not be used for harmful defects such as layering, scarring and cracks. Surface quality has specific provisions in the standard, stainless steel Angle geometry deviation allowed range also has stipulated in the standard, generally including bending, thick, apex Angle and width, while theoretical weight, etc, and stainless steel Angle, stainless steel Angle shall not have a significant twist. Common use of stainless steel angle bar Stainless steel angle bar is widely used in various building structure and engineering structure, from the civilian beams, and warehouse shelves, equipment frame base, to industrial Bridges, transmission tower, lifting transportation machinery and even military ship, industrial furnace, reaction tower, container frame. Different force components can be composed of different structures, which can also be used as the connecting parts between the components. Stainless steel angle bar, for example, is comparable to other materials, such as Angle iron. But the cost is higher, not all applicable occasions will be built with the steel Angle of the stainless steel. Appendix: the material and specifications of stainless steel angle bar Stainless steel angle bar spot material: 201, 202, 301, 202, 301 (0 cr18ni9), 304 l (00 cr19ni10), 316 (0 cr17ni12mo2), 316 l (00 cr17ni14mo2), 309 s (0 cr23ni13), 310 s (0 cr25ni20), 321 (1 cr18ni9ti), 410 s (1 cr13), 420 j1 (2 cr13), 430 (1 cr17), 317, 347, 403, 405, 403 l. Source: China Angle Bar Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

316 stainless steel pipes are widely used in seawater environment, but they have limited corrosion resistance in contact with seawater and cannot resist corrosion in all states. They are prone to local corrosion, mainly of crack corrosion and pitting. This limits their application in the environment in which they are exposed to seawater. Determine the corrosion resistance of 316 stainless steel pipes in seawater Many of the workers involved in this area have reported on the factors that determine the corrosion and applicability of 316 stainless steel pipes. These factors work together, mainly including: The water quality The velocity The temperature Oxygen content Cathodic protection The water quality The amount of chloride varies by region and tide. Even in a slightly salty water, the chloride content is higher than the amount of water in the water that is a corrosive threat. Intermittent exposures in sea water, such as tidal zone, corrosion risk would be small, that it may be that the steel surface by water level change happens when effective flushing effect. However, if the chloride is concentrated in wet and rainy conditions, evaporation of water in the spray area increases the risk of corrosion. It is important not to expose seawater to the stainless-steel pipes. The stainless steel pipe section dealing with seawater may be damaged in the short term. Free drainage surface and avoid horizontal pipe movement are important for the successful use of 316 stainless steel pipes in contact with seawater. If the piping system USES seawater for water pressure tests, the test must be drained and washed immediately, or it will corrode the 316 system. The velocity Higher velocity is desirable (generally greater than 1 m/s). Slow moving water helps biopollution, and then leads to protection or crack corrosion. Be sure to avoid stagnant water. Increasing the flow rate reduces the risk of corrosion, so it is perfectly possible to use 316 stainless steel pipes in water, such as pumps. The water temperature Crack corrosion increases with temperature, so it is not recommended for steel to contact hot water. The northern European waters are about to reach the maximum temperature at room temperature of 316 stainless steel pipes, even if other conditions are favorable. Stress corrosion cracks are usually not considered under the use of 316 (however, higher temperatures may lead to crack corrosion and pitting). Oxygen content in water (except gas) Stainless steel relies on oxygen to maintain its passivation, whereas oxygenated water is more corrosive than air. It has been found that very low oxygen levels, such as those in the sea about 200 meters deep, are very aggressive. This reduces the rate of erosion. Cathodic protection Cathodic protection is used in electrology, by means of contact with the weak and weak metal including carbon steel and aluminum. Direct contact with these metals, at the expense of other metals, will help improve the corrosion resistance of 316 stainless steel. While stainless steel is beneficial, it should also be considered that the overall durability of the products involved in this combination may be reduced. Cracking (surface level and cleaning after processing) The crack and the related etching mechanism are local corrosion, usually the cause of damage when 316 stainless steel pipes work in seawater. They can happen in the following process: Design geometry (point or groove) Flange seams with gaskets Mechanical fastening system Intercrystalline corrosion can be detected in 316 stainless steel pipes in seawater after the laboratory sensitization (heat treatment). The use of low carbon 316L, such as 14404 or 1.4432, should avoid this additional corrosion risk in the welding structure. The surface smoothness of the welding quality and the precision of steel are the important reasons for the successful application of 316 stainless steel pipes in seawater, which may be more important, such as the actual chlorine content. Smooth, clean and smooth seams are good for corrosion resistance of steel. Source: China Steel Pipe Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Generally, the measures taken to improve the impact toughness of duplex stainless steel fittings are nothing but the following: 1. reduce the carbon content of dual phase steel pipe fittings; 2., increase the ratio of manganese to carbon (Mn/c); 3. adding alloying elements, such as Ni, Cr, Mo, etc.; 4. reduce sulfur content; 5. reduce the sulfur content inclusion in duplex stainless steel pipe fittings and improve the morphology of sulphide inclusion; 6., the use of furnace refining process; 7. improved heat treatment In the above measures, the improvement of heat treatment is the first choice that should be paid attention to, because: 1. does not result in significant adjustments in the casting process; 2. do not have to add equipment; 3. production costs are increasing little. Source: China Duplex Stainless Steel Pipe Fittings Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)

Stainless steel has the ability to resist atmospheric oxidation — that is, stainless steel, but also in the acid, alkali, salt medium is the ability to corrosion – that is, corrosion resistance. But its corrosion resistance is the size of its steel chemical composition, plus the state, the use of conditions and environmental media type and change. Such as 304 stainless steel pipe fittings, in the dry and clean atmosphere, there is absolutely excellent resistance to corrosion, but it moved to the beach area, in a large amount of salt containing sea fog, will soon rust; and 316 steel performance good. Therefore, not any kind of stainless steel, in any environment can be resistant to corrosion, no rust. Stainless steel is the surface of the formation of a thin layer of thin and strong and stable stable chromium oxide film (protective film), to prevent the continued infiltration of oxygen atoms, continue to oxidize, and the ability to obtain corrosion resistance. Once for some reason, the film has been constantly destroyed, the air or liquid oxygen atoms will continue to infiltrate or metal iron atoms continue to precipitate out to form loose iron oxide, metal surface will continue to rust. But does not mean that no rust, stainless steel pipe fittings is not easy to rust and the composition of stainless steel has a great relationship. Stainless steel components in addition to iron, there are chromium, nickel, aluminum, silicon and so on. General stainless steel chromium content is generally not less than 12%, high or even up to 18%. Steel added chromium and other elements, you can change the performance of steel, such as steel, such as the molecular structure is more uniform in the steel surface is more likely to generate a layer of dense oxide protective film, etc., thereby greatly improving the ability of stainless steel corrosion resistance. So stainless steel can resist fire, water, acid, alkali and a variety of solutions to its corrosion, no rust. Scientists have found that the more uniform the internal structure of steel, the more closely connected components, the more difficult the corrosive invasion, coupled with the surface and attached a layer of oxide protective film, like steel to wear armor, natural It is not easy to rust. The optimum temperature for stainless steel pipe fittings is 1050-1080 ° C. The temperature quickly rose to this degree, according to the thickness of stainless steel pipe fittings to stay 1-3 minutes, and then quickly cooled to 100 ℃ below, remember to be rapid cooling, because 500-800 degrees Celsius are stainless steel sensitization temperature, stay in this range Too long will affect the molecular structure of stainless steel, leading to material changes. Source: China Pipe Fittings Manufacturer – wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)