Precision seamless steel pipes are high-precision tubes manufactured through cold drawing or hot rolling processes. Unlike conventional seamless pipes, they feature a smooth inner and outer surface without an oxide layer, allowing them to withstand high pressure with no leakage. These pipes offer excellent dimensional accuracy, superior surface finish, and the ability to undergo cold bending, flaring, and flattening without cracking. They are widely used in the production of pneumatic and hydraulic components, such as cylinders and other precision-engineered parts.
The key difference between precision steel pipes and standard seamless steel pipes lies in their manufacturing process and specifications. Seamless steel pipes are typically produced without weld seams, making them suitable for high-pressure applications. They can be either cast or cold-drawn, often resulting in a rougher surface. On the other hand, precision steel pipes are a more recent development, designed with tight tolerances on both inner and outer dimensions, ensuring consistent quality and performance.
Cold-drawn precision steel pipes have several distinct characteristics:
1. Smaller outer diameter compared to hot-rolled pipes.
2. High precision allows for small-batch production with consistent quality.
3. Excellent surface finish due to the cold working process.
4. More complex cross-sectional shapes can be achieved.
5. Improved mechanical properties and denser metal structure.
These pipes are manufactured according to various international standards, including GB/T 3639, GB/T 8713, DIN 2391-2, and HK15-2000.
They are commonly used in the manufacturing of mechanical structures, hydraulic systems, and automotive components. The delivery condition of the pipes varies depending on the required processing and application. Common delivery states include:
- **Cold processed / Hard (BK):** No heat treatment after the final cold working, allowing only minimal deformation.
- **Cold processed / Soft (BKW):** Heat treatment is applied after the final cold working to allow limited deformation, such as bending or flaring.
- **Annealed (BKS):** Final annealing below Ac1 temperature to relieve cold working stresses.
- **Fully Annealed (GBK):** Complete annealing in a protective atmosphere after cold working.
- **Normal Cold (NBK):** Final cold working followed by protection during the heating process.
These options ensure that the pipes meet specific performance and formability requirements, making them versatile for a wide range of industrial applications.
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