Cold formed hollow steel with complete specifications for hot-dip galvanized rectangular tube structure

Description :

  Galvanized strip rectangular tube is a square or rectangular section hollow steel that is formed by cold bending hot-rolled or cold-rolled strip steel and welded, and is protected against corrosion by the zinc layer of the galvanized strip steel itself. This product mainly solves the comprehensive requirements for material strength, lightweight, and corrosion resistance in building structures, mechanical manufacturing, and steel structure engineering. Compared to the traditional black pipe galvanizing process, the production process of galvanized square rectangular pipes is shorter, more cost-effective, and has a higher surface finish. Typical working conditions include greenhouse skeleton construction, lightweight steel structure factory columns, shelf manufacturing, guardrail handrails, and support frames for various mechanical equipment. Its core advantage lies in the strong bond between the zinc layer and the substrate, which can provide long-lasting rust protection in general atmospheric environments. At the same time, it has excellent cold bending and welding performance, making it easy to process and install in the future. It is one of the widely used basic building materials in modern industrial and construction fields.

  The specifications of this product include key indicators such as edge length, wall thickness, length, and zinc layer weight. The common side length ranges from 20mm to 400mm, and the wall thickness is usually between 1.0mm and 12mm. Non standard sizes can be customized according to customer needs. The standard length is generally 6 meters or 12 meters, and cutting can also be negotiated according to transportation conditions. Materials such as Q195, Q215, Q235B and other low carbon steels are commonly used to ensure good plasticity and toughness. The adhesion amount of zinc layer on galvanized strip raw materials is generally between 60-270g/m ², depending on the galvanizing process of the original strip (such as hot-dip plating or electroplating). The implementation standards usually refer to GB/T 3094-2012 "Cold drawn special-shaped steel pipes" or GB/T 6728-2017 "Cold formed hollow section steel for structural use". The surface has a silver white metallic luster, without missing plating, black spots or bubbles, the weld seam is smooth and flat, without obvious burrs, high dimensional accuracy, good straightness, and meets the strict restrictions on bending and twisting in national standards, ensuring the convenience and aesthetics of construction and assembly.

  In the selection process, it is necessary to clearly distinguish the differences in application scenarios between galvanized rectangular pipes and black hot-dip galvanized pipes. Galvanized square rectangular pipes are suitable for indoor dry environments or structural components with moderate anti-corrosion requirements, such as indoor shelves, decorative keels, lightweight sheds, etc., due to their thin zinc layer and pre galvanized nature; If used in outdoor highly corrosive environments, coastal areas, or long-term immersion in water, it is recommended to choose black pipe hot-dip galvanized products with thicker wall thickness and zinc layer or undergo additional anti-corrosion treatment. When making a purchase, special attention should be paid to the wall thickness tolerance to avoid excessive negative deviation affecting the load-bearing capacity. For structures that require welding, it is important to note that high temperatures during welding can damage the zinc layer around the weld seam. After welding, zinc supplementation and anti-corrosion treatment must be carried out to prevent corrosion from spreading from the weld seam. In addition, the performance differences of strip steel substrates from different origins can also affect the risk of cold bending cracking in the final product. It is recommended to conduct sample bending tests before large-scale procurement to ensure that the mechanical performance requirements of specific projects are met.

  In terms of installation and maintenance, the exposed substrate cut of galvanized rectangular pipes after cutting, drilling or welding is prone to rusting, and must be repaired in a timely manner with zinc rich paint or special anti rust spray to maintain the integrity of the overall anti-corrosion system. When stacking and storing, a dry and ventilated area should be selected, with a raised bottom to prevent ground moisture erosion, avoid contact with acidic and alkaline substances, and prevent chemical corrosion of the zinc layer. In daily use, regularly check whether there are signs of looseness or rust on the connecting nodes, especially in humid environments. If white rust (zinc oxide) or black spots are found on the surface, they should be cleaned and rust proof oil should be applied in a timely manner. Although the galvanized layer has self-healing ability, severe scratches require manual intervention. Reasonable design and standardized construction can significantly extend the service life of galvanized rectangular pipes, reduce maintenance costs throughout the entire lifecycle, ensure structural safety and stability, and are suitable for various long-term service building and mechanical projects.

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