| Customization: | Available |
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| Application: | Chemical Industry, Construction Industry, Oil and Gas Industry, Water Treatment Plants, Building Material |
| Carbon Content: | Steel Welded Pipe |
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Analysis Aspect
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Details
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Standard Compliance
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Complies with ASME SA249. This standard is dedicated to seamless and welded austenitic stainless steel boiler, superheater, heat - exchanger, and condenser tubes. It sets strict requirements for material quality, manufacturing processes, and testing procedures, ensuring high - quality products for critical applications.
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Material
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- Primarily made of austenitic stainless steel grades such as 304, 304L, 316, 316L, etc. For example, in grade 304 stainless steel, the chemical composition typically includes chromium (18.0 - 20.0%), nickel (8.0 - 10.5%), carbon (max 0.08%), manganese (max 2.0%), silicon (max 1.0%), phosphorus (max 0.045%), and sulfur (max 0.030%). - These alloys endow the pipes with excellent corrosion resistance, especially against oxidation, pitting, and crevice corrosion. The high chromium content forms a passive oxide film on the surface, protecting the pipe from further corrosion.
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Manufacturing Process
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- Welding processes: High - quality welding techniques like Tungsten Inert Gas (TIG) welding or Electric Resistance Welding (ERW) are commonly used. TIG welding provides precise control over the weld pool, resulting in high - quality, clean welds with minimal spatter and porosity. ERW, on the other hand, is efficient for high - volume production while maintaining good weld integrity. - Tube forming: The steel strip is first formed into a tubular shape, and then the edges are welded together. Precise forming equipment is used to ensure accurate dimensions and roundness of the pipe. - Heat treatment: Solution annealing is often carried out after welding. This process involves heating the pipe to a specific temperature (usually around 1010 - 1120°C for austenitic stainless steels) and then rapidly cooling it. This helps to relieve internal stresses, homogenize the microstructure, and restore the corrosion resistance of the material.
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Mechanical Properties
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- High tensile strength: Austenitic stainless steel pipes under ASME SA249 have relatively high tensile strength values. For instance, grade 304 stainless steel typically has a minimum tensile strength of 515 MPa. This allows the pipes to withstand high - pressure and high - stress conditions in applications such as boilers and heat exchangers. - Good yield strength: The yield strength is also substantial, enabling the pipes to resist plastic deformation under normal operating pressures. For grade 304, the minimum yield strength is around 205 MPa. - High elongation: These pipes exhibit good elongation properties, usually around 40% for grade 304. This means they can deform to a certain extent without fracturing, providing flexibility and toughness in service.
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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, the outer diameter tolerance may be within ±0.05 mm, while for larger - diameter pipes, it could be within ±0.5% of the nominal outer diameter. - 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, depending on the pipe size and application requirements. - Straightness: The pipes are manufactured to be highly straight, with a maximum allowable deviation from straightness per unit length. This is important for easy installation and to ensure proper fluid flow.
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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, minimizing pressure drop in systems where the pipes are used for transporting fluids such as water, steam, or corrosive chemicals. - Round cross - section: The precise forming process ensures a round cross - section, which promotes uniform flow distribution and reduces the likelihood of flow turbulence. This is crucial for efficient heat transfer in heat - exchanger applications.
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Weld Quality
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- Stringent inspection: All welds are thoroughly inspected using non - destructive testing methods such as radiographic testing, ultrasonic testing, and dye penetrant testing. These methods can detect internal and surface defects like cracks, porosity, and lack of fusion. - Weld strength: The welded joints are designed to have strength equal to or greater than the base metal. This ensures the integrity of the pipe under pressure and mechanical loads. - Corrosion resistance of welds: The welding process and post - weld heat treatment are optimized to maintain the corrosion resistance of the base metal in the weld area. This is essential for applications in corrosive environments.
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Application Range
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- Power generation: Widely used in boilers, superheaters, and condensers in power plants. They can handle high - temperature and high - pressure steam, as well as corrosive water and chemicals in the power generation process. - Chemical industry: Suitable for transporting various corrosive chemicals due to their excellent corrosion resistance. They are used in chemical reactors, heat exchangers, and pipelines for the transfer of acids, alkalis, and other aggressive substances. - 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 cleaning and sterilization procedures without contamination. - Pharmaceutical industry: Essential for the pharmaceutical manufacturing process, where strict hygiene and corrosion - free conditions are required. They are used in pipelines for transporting raw materials, process fluids, and in equipment such as reactors and distillation columns.
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Size Range
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- Outer diameter: Available in a wide range, from small - diameter pipes as small as 6.35 mm (1/4 inch) for some specialized applications to large - diameter pipes up to 610 mm (24 inches) or even larger for industrial applications. - Wall thickness: Wall thickness options vary depending on the application requirements and pressure ratings. Common wall thicknesses range from 0.5 mm to 10 mm or more, with different schedules (e.g., SCH10, SCH20, SCH40) available to meet 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. - Pickled finish: After pickling in an acid solution, the surface oxide layer is removed, enhancing the corrosion resistance and giving the pipe a brighter appearance. - Polished finish: A highly polished surface can be achieved through mechanical polishing or electropolishing. This is especially useful in applications where a smooth surface is required to minimize product adhesion or for aesthetic purposes, such as in the food and pharmaceutical industries. - Coated finish: Pipes can be coated with various materials like epoxy, polyurethane, or polyethylene for additional corrosion protection in extremely harsh environments.
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