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With the development of the economy and society, the industrial production process and people’s lives produce more and more “three wastes” (waste gas, waste water, waste residue) that are threatening people’s homes to survive. The “three wastes” for recycling, purification treatment, or comprehensive use, to achieve standard discharge, to prevent environmental pollution, and waste into treasure, for the benefit of mankind. Duplex stainless steel, because of its unique physical and chemical properties, is one of the materials of choice for the manufacture of “three wastes” recycling and purification equipment and facilities.

Duplex stainless steel has the advantages of both ferritic and austenitic stainless steel, with good corrosion resistance, mechanical properties, and welding properties. Due to its excellent overall performance and manufacturing technology breakthroughs, in recent years has been used in large quantities for the manufacture of equipment under the conditions of chloride and hydrogen sulfide media, especially suitable for the manufacture of heat exchangers containing chloride-ionized water or brackish water cooling media, but also for the manufacture of dilute sulfuric acid solutions and storage and transportation of pure organic acid equipment. In place of 304 stainless steel in heavily loaded structural materials, it also improves the service life of the equipment and reduces material costs. In recent years, due to the development of industrial level and increasingly high requirements for environmental protection, duplex stainless steel in the field of environmental protection has also been widely used, especially in industrial waste gas, wastewater, and solid waste treatment is widely promoted.

Exhaust gas treatment

Exhaust gas pollution is one of the biggest environmental problems facing mankind, such as coal-fired boilers in power plants, gas furnaces in fertilizer plants, and coke ovens in iron and steel plants contain a large number of harmful gases and toxic dust particles such as sulfide, nitrides, chlorides, fluorides, etc., which need to be removed before discharge into the atmosphere, the most common method is to pass the exhaust gas through the absorption tower equipped with lime slurry or limestone The most common method is to neutralize the waste gas by passing it through an absorption tower with lime slurry or limestone, which generates corrosive gases containing HCl and HF, causing severe corrosion to the absorption tower. Therefore, in order to ensure the continuous operation of the system, it is necessary to use good corrosion resistance of stainless steel, and 2205, and 2507 duplex stainless steel has the advantages of this, so in the flue gas treatment absorption tower device is used in large quantities.

Statistics show that in recent years in Europe to build a number of sets of flue gas desulfurization devices are used in a large number of duplex stainless steel manufacturing. Canada Coleson Cove power plant is the first in North America at the top of the absorption tower using 360 tons of 2205 duplex stainless steel. In recent years, domestic industrial flue gas treatment equipment also began to use duplex stainless steel materials, such as Huadian International Zouxian Power Plant Phase III flue gas desulfurization absorption tower also uses a large number of 2205, 2507 duplex stainless steel as a manufacturing material. At the same time in the flue gas dust treatment system, the wet type electric dedusting technology (WESP) device system dust collection plate, anode plate, and cathode line using 2205 duplex stainless steel manufacturing. In the pharmaceutical enterprise industry organic waste gas treatment system, its pneumatic switching valve body is made of 2205 duplex stainless steel. Due to the requirements of the environment, ships, especially chemical ships’ flue gas desulfurization emission absorption towers also have a large number of 2205, 2507 duplex stainless steel manufacturing.

Wastewater treatment

With the construction of cities and towns and industrial processes at home and abroad, the discharge of wastewater has become the culprit affecting the deterioration of global water resources and needs to be treated harmlessly before it can be discharged. Municipal sewage, hospital sewage, livestock breeding sewage, etc. contain a large number of Cl- ions, phosphorus compounds, nitrogen compounds, organic compounds, etc., especially the content of these ions or compounds in the sludge is higher. The content of various metal ions, Cl- ions, phosphorus compounds, nitrogen compounds, organic compounds, etc. in industrial wastewater is also high. If these ions or compounds are discharged without treatment, they will cause significant pollution to the water environment and pose a major threat to human life.

As some of the equipment or piping systems in the sewage treatment system are permanently built, and urban and industrial sewage, sludge is corrosive, such as improper selection of materials not only to sewage treatment equipment, piping systems cause serious corrosion, sewage treatment equipment or piping systems maintenance difficulties, sewage treatment companies will also cause significant economic losses. So sewage treatment equipment and piping systems need to choose corrosion-resistant materials manufacturing.

Wastewater treatment equipment and piping systems are generally made of 304 stainless steel, but the sewage Cl- greater than 200ppm, wastewater, and sewage treatment equipment or piping systems are best used 2205 duplex stainless steel or better corrosion resistance 2507 super duplex stainless steel manufacturing, such as stainless steel pickling plant, auto parts plating plant, pulp or paper mills, mines, coal chemical industry, chemical fertilizer plant, the phosphate fertilizer plant, sugar plant, brewery and other industrial waste liquids, sewage treatment systems or equipment are manufactured using 2205, 2507 duplex stainless steel materials.

Waste treatment

The same as sewage treatment and waste fume treatment, duplex stainless steel in the solid waste treatment process is also used in large quantities, this is because the solid waste contains a large number of metal ions, a variety of complex organic substances, chlorides, fluoride, sulfides, etc., these substances are not only toxic but also acidic and alkaline, in the treatment process of serious corrosion of equipment. Solid waste treatment systems with strong corrosive properties of solid waste contact parts, and piping systems need to use duplex stainless steel material manufacturing.

Toxic, acidic, and alkaline chemical, petroleum, pharmaceutical, and other solid waste combustion process, the need for its harmless treatment, solid waste treatment system configuration of the scrubber tower, and wet electrostatic equipment are manufactured using 2205, 2507 duplex stainless steel. In the electroplating solid waste or other solid waste containing rare metals such as gold, silver, cobalt, etc., the use of mixing equipment, piping, and electrolytic purification equipment is used in a large number of 2205, 2507 duplex stainless steel manufacturing. In the Metallurgical manufacturing industry, such as carbon steel, stainless steel pickling solid waste treatment of mixing equipment, ball making equipment local parts also have used 2205 duplex stainless steel.

In summary, because of the excellent mechanical properties of duplex stainless steel, wear resistance, stress corrosion, chloride ion corrosion, and resistance to uniform corrosion performance and other comprehensive excellent performance, its application in the field of environmental protection is becoming more and more widespread.

Hello everyone, today I would like to share with you the properties of stainless steel sheets. A stainless steel sheet is a widely used metal material with good corrosion resistance, strength, and workability. It is widely used in manufacturing, construction, chemical industry, and other fields.

First, the corrosion resistance of stainless steel sheets is excellent. This is because there is a dense chromium oxide layer on the surface of stainless steel sheets, which can effectively prevent oxidation, corrosion, and wear, thus keeping the appearance and performance of stainless steel sheets unchanged for a long time. In addition, the corrosion resistance of stainless steel sheets is also affected by their alloy composition and manufacturing process.

Secondly, stainless steel plate has high strength and hardness. The strength and hardness of this material can be adjusted according to the needs of the application, so stainless steel plate is widely used in manufacturing and construction. In addition, stainless steel sheet also has good workability and can be stamped, bent, sheared, and other processing according to the need to adapt to a variety of different applications.

Finally, the performance of stainless steel sheets is also affected by their surface treatment and surface quality. Surface treatment can change the color, texture, and luster of the stainless steel plate, making it more beautiful and durable. Surface quality includes indicators such as surface flatness, surface finish, and surface defects, which directly affect the service life and performance of stainless steel sheets.

In short, stainless steel sheet is a metal material with excellent performance, good corrosion resistance, strength, and workability. Stainless steel sheet performance is widely used in manufacturing, construction, chemical industry, and other fields, providing strong support for the development of various industries.

C71500 is a copper-nickel alloy, also known as copper-nickel 70/30 alloy. It consists mainly of 70% copper (Cu) and 30% nickel (Ni) with small amounts of iron (Fe) and manganese (Mn). C71500 has good corrosion resistance and mechanical properties and is suitable for a wide range of industrial applications.

The following are some of the characteristics and applications of C71500 alloy:

Corrosion resistance: C71500 alloy has excellent corrosion resistance, especially to seawater and saltwater environments. Therefore, it is commonly used in marine engineering, seawater cooling systems, ship components, etc.

Mechanical properties: C71500 alloy has good strength and toughness, and can maintain stable mechanical properties over a wide range of temperatures. It has good impact toughness and plasticity and is suitable for the manufacture of pipelines, valves, pump bodies, and other components requiring strength and reliability.

Welding properties: C71500 alloy has good weldability and can be joined and fabricated by common welding methods (such as gas-shielded welding, arc welding, etc.).

Thermal conductivity: C71500 alloy has high thermal conductivity and can be used in applications requiring high thermal conductivity, such as heat exchangers, radiators, etc.

C71500, also known as copper-nickel 70/30 alloy, has the following physical and chemical properties:

Physical properties:

Density: approximately 8.94 g/cm3.

Melting Point: Approximately 1170°C (2140°F).

Coefficient of Thermal Expansion: The linear coefficient of thermal expansion is approximately 13.2 x 10^-6/°C at room temperature.

Thermal conductivity: The thermal conductivity is approximately 30.7 W/(m-K) at room temperature.

Electrical conductivity: The electrical conductivity is approximately 7.6 MS/m at room temperature.

Chemical properties:

Main composition: C71500 alloy consists mainly of 70% copper (Cu) and 30% nickel (Ni), with small amounts of iron (Fe) and manganese (Mn).

Corrosion resistance: C71500 has good corrosion resistance to corrosive media such as seawater, salt water, and acidic and alkaline solutions.

Strength: C71500 alloy has good strength and toughness and can maintain stable mechanical properties over a wide range of temperatures.

Magnetism: C71500 alloy is non-magnetic at room temperature.

C71500 alloy has a wide range of applications in many fields, common applications include

Marine engineering: With its excellent corrosion resistance and resistance to seawater erosion, C71500 alloy is commonly used in the manufacture of marine engineering equipment and components, such as seawater coolers, saltwater pipes, ship components, etc.

Chemical industry: Due to its good corrosion resistance, C71500 alloy is suitable for chemical process equipment, distillers, furnace tubes, heat exchangers and catalyst carriers, etc.

Power industry: C71500 alloy is used to manufacture components such as coolers, condensers, and heat exchangers for electric power generation equipment to provide efficient heat transfer and corrosion resistance.

Food processing: C71500 alloy meets sanitary standards and can be used in food processing equipment and containers, such as food cans, pipes, and parts that come into contact with food.

Special Requirements:

Corrosion resistance: C71500 alloy should have good corrosion resistance, especially to corrosive media such as seawater, salt water, and acidic and alkaline solutions.

Mechanical properties: C71500 alloy needs to have certain strength, toughness, and plasticity to meet the requirements of specific applications.

Weldability: C71500 alloy needs to have good weldability for reliable welded connections during fabrication and installation.

Heat Treatment and Aging: Depending on the requirements of a specific application, C71500 alloy can be heat treated and aged to improve its properties and corrosion resistance.

Quality Control: Strict quality control, including material testing, process monitoring, and product inspection, is required during the production and manufacture of C71500 alloy to ensure the quality and consistency of the alloy.

In summary, C71500 alloy has a wide range of applications in offshore engineering, chemical, power, and food processing, where special requirements such as corrosion resistance, mechanical properties, welding properties, heat treatment requirements, and quality control need to be met. These requirements are key factors in ensuring the excellent performance and reliability of C71500 alloy in specific environments.

Stainless steel has good overall performance and good surface characteristics and has a wide range of applications in all walks of life. Similarly, stainless steel pipe is no exception. Stainless steel pipe is a kind of steel with a hollow section, generally divided into stainless steel seamless pipe and welded pipe. They also have certain differences in processing methods and performance, the differences are as follows:

First, the difference in the production process

Stainless steel welded pipe is made of steel plate or strip after the unit and mold curling and forming welded, the tube wall generally has a weld; and a seamless tube is used as a round billet for perforation of raw materials, through the production process of cold rolling, cold drawing or hot extrusion made, there is no welding point on the tube.

Second, the difference in the appearance of steel pipe

Stainless steel welded pipe, the tolerance of its wall thickness is very small, and the wall thickness of the entire circumference is very uniform; the high precision of steel pipe, and high brightness of the inner and outer surface of the tube, can be arbitrarily sized; can do thin-walled tube. In contrast, the steel tube of seamless pipe has low accuracy, uneven wall thickness, low brightness of the inner and outer surface of the tube, high cost of sizing, and the inner and outer surfaces of the pockmark and black spot are not easy to remove. Therefore, the production of seamless pipe walls is usually thicker.

Third, the difference in performance and price

Seamless pipes are much higher than welded pipes in terms of corrosion resistance and pressure and high-temperature resistance. With the improvement of the production process of welded pipes, mechanical properties, and mechanical properties are slowly approaching seamless pipes. Seamless pipe is more complicated in the production process, and it is more expensive than welded pipe. Based on the characteristics and differences between seamless and welded stainless steel pipe, the application should be reasonably selected to achieve economical, beautiful, and reliable results: 1, used as a decorative tube, product tube, or prop tube, generally requires a good surface effect, usually choose stainless steel welded pipe; 2, for general lower pressure fluid transfer, such as the transfer of water, oil, gas, air and heating hot water or steam and other low-pressure systems, usually Choose stainless steel welded pipe; 3, for the pipeline used in industrial engineering and large equipment to transport fluids, as well as power stations, nuclear power plant boilers, require high-temperature and high-pressure, high-strength transport fluid pipeline, should be selected seamless stainless steel pipeline; 4, stainless steel welded pipe is generally used for liquid transport below 0.8MPa, a seamless pipe can be used to withstand the liquid transport above 0.8MPa. If the pressure requirements are not high, the use of welded pipe will be more economical.

Four, stainless steel seamless pipe advantages and disadvantages

Advantages: forming speed, high yield, can be made into a variety of cross-sectional forms to adapt to the needs of the conditions of use; cold rolling can make a large plastic deformation of steel, thereby increasing the yield point of steel. Hot rolling can destroy the casting organization of the ingot, refine the grain of the steel, and eliminate microstructural defects so that the steel organization is dense and the mechanical properties are improved. Disadvantages: 1, metal delamination – steel after cold rolling, the steel internal non-metallic inclusions (mainly sulfides and oxides, and silicates) are pressed into thin sheets, the phenomenon of delamination (sandwich). Delamination makes the steel along the thickness of the direction of the force performance greatly deteriorate, and there is a possibility of interlayer tearing when the weld expands. 2, uneven wall thickness – we are familiar with the metal has thermal expansion and contraction, due to rolling to the end of the cold-rolled steel pipe even if the length, and thickness are up to standard, the final cooling will still appear a certain negative difference, this The larger the negative difference, the worse the uniformity of the wall thickness. Therefore, the wall thickness, length, straightness, and ellipticity of cold-rolled seamless steel tubes can not be required to correct. 3, residual stress – due to uneven cooling, a variety of cross-sectional steel tubes have residual stress, the larger the cross-sectional size of the steel, the greater the residual stress, under the action of external forces has a certain impact on performance. Such as deformation, stability, fatigue resistance, etc. may have a detrimental effect. 4, poor surface finish – the inner surface of the steel pipe tensile marks are longitudinally distributed, showing a symmetrical or single linear fold, some through-length presence, and there is also a local presence.

Conclusion

Seamless pipe due to the complexity of the production process, the wall thickness uniformity is poor, the inner and outer wall surface roughness is poor, the actual operation is easy to make the chloride ion (or sulfur ion) substances (such as organic matter) bonded in the stainless steel pipe wall, the formation of a local anoxic acidic environment, so that the inner wall passivation film dissolved lose the protective effect on the metal, the metal directly in contact with the medium in the acidic environment, as the anode lost electrons and formed with water Hydroxide, hydroxide in the hydroxide is replaced by chlorine and dissolved in water, reducing the anodic passivation effect. Bond as a cathode to capture the hydrogen ions generated by the inner wall to form hydrogen gas, and with the inner wall of the metal reaction products together with the outward discharge, with the depth of the reaction, the wall of the metal is constantly corroded to form hole corrosion, the hole will gradually deepen and increase. When the temperature rises to 50 degrees above the pitting corrosion accelerates, the higher the temperature pitting corrosion faster. In large stress, conditions will also occur under the stress corrosion and stress corrosion expansion characteristics. In addition, the seamless tube in the welding process will produce a variety of instability, not easy to weld, and weld impermeable.

Five, stainless steel welded steel pipe advantages

Stainless steel welded steel pipe – uniform wall thickness of stainless steel strip in the gas protection without the addition of solder fusion welding once rolled into shape.

Advantages: 1. uniform wall thickness – the parent material for the forming strip, wall thickness consistency, high surface finish, to achieve industrial clean surface level 2B. 2. low residual stress – forming the steel tube using a high temperature higher than 1040 degrees for bright annealing stainless steel tube stress relief. 3. High weld strength – welding using melt welding, the material composition remains unchanged after high-temperature heat treatment of the weld and the parent material has the same intergranular structure, the weld is flattened, reverse bending, flaring and other damage experiments, the weld will not crack or cracks, burrs, and other problems. In addition to this, eddy current testing and water pressure or gas test should be done to ensure the quality of the tube. 4. Good consistency – good consistency of the outer diameter, wall thickness, length, and straightness of the tube, and high processing accuracy.