| Customization: | Available |
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| Application: | Chemical Industry, Oil and Gas Industry, Building Material |
| Certification: | CE, ISO9001 |
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Analysis Aspect
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Details
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Standard Compliance
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Complies with EN 10217 - 7, which is a European standard for welded steel tubes for pressure purposes. This standard specifically focuses on stainless steel welded pipes. It details requirements for materials, dimensions, tolerances, manufacturing processes, and inspection methods. Compliance ensures that the pipes meet the high - quality and safety standards for use in pressure - bearing applications across Europe and in international markets that recognize this standard.
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Material
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- Utilizes a variety of stainless steel grades, including austenitic (e.g., 1.4301, equivalent to 304 in the American system), austenitic - ferritic (duplex, such as 1.4462, equivalent to 2205), and ferritic grades. - For austenitic grade 1.4301, the chemical composition typically includes chromium (17.5 - 19.5%), nickel (8.0 - 10.5%), carbon (max 0.07%), manganese (max 2.0%), silicon (max 1.0%), phosphorus (max 0.045%), and sulfur (max 0.015%). - Austenitic grades offer excellent corrosion resistance in a wide range of environments, including general atmospheric, water, and many chemical media. The chromium content forms a passive oxide film on the surface, protecting the pipe from corrosion. Duplex grades combine the advantages of austenitic and ferritic stainless steels, providing high strength along with good corrosion resistance, especially against pitting and stress - corrosion cracking. Ferritic grades are known for their resistance to stress - corrosion cracking and are often used in applications where cost - effectiveness and moderate corrosion resistance are required.
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Manufacturing Process
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- Welding Techniques: High - precision welding methods are employed. Tungsten Inert Gas (TIG) welding is commonly used for producing high - quality, clean welds with minimal heat - affected zone. It allows for precise control of the weld pool, resulting in strong and aesthetically pleasing joints. Another technique is Metal Inert Gas (MIG) welding, which is suitable for higher - speed production while still maintaining good weld quality. For large - scale production, Electric Resistance Welding (ERW) may also be used, where the edges of the steel strip are heated and pressed together to form a weld. - Tube Forming: The manufacturing process starts with a stainless - steel strip. This strip is first formed into a tubular shape using specialized machinery. The forming process ensures accurate dimensions and a round cross - section. Precise control over the forming parameters is crucial to meet the dimensional tolerances specified in the EN 10217 - 7 standard. - Heat Treatment: Depending on the steel grade and application requirements, heat treatment may be carried out. Solution annealing is common for austenitic stainless steels. This involves heating the pipe to a specific temperature (usually around 1010 - 1120°C for 1.4301) and then rapidly cooling it. The process relieves internal stresses, homogenizes the microstructure, and restores the optimal corrosion resistance and mechanical properties of the material. For duplex stainless steels, a two - step heat treatment may be applied to balance the austenite and ferrite phases and enhance the overall performance.
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Mechanical Properties
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- High Tensile Strength: Stainless steel welded pipes under EN 10217 - 7 exhibit high tensile strength. For example, grade 1.4301 has a minimum tensile strength of around 520 MPa. This enables the pipes to withstand significant internal pressure and external mechanical loads in applications such as pipelines for transporting fluids under pressure. - Good Yield Strength: The yield strength is also substantial. For 1.4301, the minimum yield strength is typically around 215 MPa. This property ensures that the pipes can resist plastic deformation under normal operating pressures and maintain their structural integrity. - Adequate Elongation: These pipes generally have good elongation properties. For grade 1.4301, the elongation at break is usually around 40%. This allows the pipes to deform to a certain extent without fracturing, providing flexibility and toughness in service, which is important in applications where the pipes may be subject to thermal expansion, vibration, or minor ground movements.
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Dimensional Accuracy
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- Outer Diameter Tolerance: Tightly controlled to ensure proper fit in installations. For small - diameter pipes (up to 50.8 mm), the outer diameter tolerance is typically within ±0.2 mm. For larger - diameter pipes (above 50.8 mm), the tolerance is within ±0.5% of the nominal outer diameter. This precision in outer diameter ensures seamless connection with other pipeline components, such as fittings and flanges. - Wall Thickness Tolerance: Strictly specified to guarantee uniform wall thickness along the length of the pipe. The tolerance is usually within ±10% of the nominal wall thickness for most applications. However, for pipes used in critical applications where precise pressure - bearing capabilities are required, the tolerance may be even tighter, down to ±5% in some cases. - Straightness: The pipes are manufactured to a high degree of straightness. The maximum allowable deviation from straightness is defined as a certain amount per unit length, for example, 1.5 mm/m. This straightness is essential for easy installation, as well as for ensuring proper fluid flow and minimizing pressure losses in pipelines.
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Flow Characteristics
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- Smooth Inner Surface: The welding process and subsequent finishing operations result in a smooth inner surface. This reduces frictional resistance to fluid flow, which is crucial in applications where the pipes are used to transport fluids such as water, steam, oil, or chemical substances. A smooth inner surface minimizes pressure drop, allowing for more efficient fluid transportation and reducing the energy required to pump the fluid through the pipeline. - Round Cross - Section: The precise tube - forming process ensures a round cross - section. A round cross - section promotes uniform flow distribution, reducing the likelihood of flow turbulence. In applications such as heat exchangers, a round cross - section also enhances heat transfer efficiency by providing a larger and more uniform surface area for heat exchange between the fluid inside the pipe and the surrounding medium.
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Weld Quality
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- Stringent Inspection: All welds are subject to rigorous inspection procedures in accordance with EN 10217 - 7. Non - destructive testing methods are extensively used. Radiographic testing is employed to detect internal defects such as porosity, cracks, and lack of fusion within the weld. Ultrasonic testing is used to identify both internal and surface - breaking defects. Dye penetrant testing is applied to detect surface - opening defects. The use of these multiple inspection methods ensures the highest quality of welds. - Weld Strength: The welded joints are designed and tested to have strength equal to or greater than the base metal. This is verified through mechanical testing, such as tensile and bend tests. The high - strength welds ensure the integrity of the pipe under pressure and mechanical loads, preventing failures at the weld locations. - Corrosion Resistance of Welds: Special attention is paid to maintaining the corrosion resistance of the base metal in the weld area. The welding process and post - weld heat treatment (if applicable) are optimized to ensure that the passive oxide film forms evenly on the weld and the adjacent base metal. This is particularly important in applications where the pipes are exposed to corrosive environments, such as in the chemical and marine industries.
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Application Range
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- Power Generation: Widely used in power plants for various applications. In steam - generating boilers, these pipes can handle high - temperature and high - pressure steam. They are also used in cooling water systems, where their corrosion resistance protects against the corrosive effects of water, often containing dissolved oxygen and other impurities. - Chemical Industry: Ideal for transporting a wide range of corrosive chemicals. They are used in chemical reactors, distillation columns, and pipelines for the transfer of acids, alkalis, and other aggressive substances. The excellent corrosion resistance of stainless steel grades specified in EN 10217 - 7 ensures the safe and long - term operation of chemical processes. - Food and Beverage Industry: Due to their hygienic properties and corrosion resistance, these pipes are used in the production, processing, and transportation of food and beverages. They can withstand the cleaning and sterilization procedures required in this industry without contamination, ensuring the quality and safety of food products. - Pharmaceutical Industry: Essential for the pharmaceutical manufacturing process, where strict hygiene and corrosion - free conditions are mandatory. They are used in pipelines for transporting raw materials, process fluids, and in equipment such as reactors, filtration systems, and distillation columns. The high - quality standards of EN 10217 - 7 - compliant pipes help meet the stringent regulatory requirements in the pharmaceutical industry. - Marine and Offshore Applications: Stainless steel welded pipes are used in marine and offshore structures, such as desalination plants, seawater cooling systems, and pipelines on oil and gas platforms. Their corrosion resistance to seawater and the harsh marine environment makes them a reliable choice for these applications.
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Size Range
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- Outer Diameter: Available in a wide range. Small - diameter pipes can be as small as 6 mm for specialized applications, while large - diameter pipes can reach up to 1200 mm or more for industrial and infrastructure projects. - Wall Thickness: Wall thickness options vary according to the application requirements and pressure ratings. Common wall thicknesses range from 0.5 mm to 20 mm or more. Different wall thicknesses are designated by standard schedules (e.g., SCH10, SCH20, SCH40), which help in selecting the appropriate pipe for a specific pressure and mechanical strength needs.
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Surface Finish
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- Mill Finish: The as - manufactured surface finish, which is smooth and clean, suitable for many general applications. It provides a basic level of protection against minor surface corrosion and is often used when the pipe will be further processed or coated. - Pickled Finish: After pickling in an acid solution (usually a mixture of nitric and hydrofluoric acids), the surface oxide layer is removed. This enhances the corrosion resistance of the pipe and gives it a brighter appearance. Pickled finish is commonly used in applications where a higher level of corrosion resistance is required, such as in chemical and marine environments. - Polished Finish: A highly polished surface can be achieved through mechanical polishing or electropolishing. Mechanical polishing involves using abrasive materials to smooth the surface, while electropolishing is an electrochemical process. A polished finish is especially useful in applications where a smooth surface is required to minimize product adhesion, such as in the food and pharmaceutical industries, or for aesthetic purposes in architectural applications. - Coated Finish: Pipes can be coated with various materials for additional corrosion protection in extremely harsh environments. Epoxy coatings are commonly used for their chemical resistance and durability. Polyurethane coatings offer good abrasion and impact resistance. Polyethylene coatings provide excellent moisture and chemical barrier properties. Coated pipes are often used in applications where the pipes are exposed to highly corrosive substances, such as in wastewater treatment plants or in pipelines transporting aggressive chemicals.
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