Answers

• 
  What are the common specifications and wall thicknesses of seamless steel pipes?

  ere are some common specifications for seamless steel pipes (outer diameter × wall thickness, mm):

  Hot-rolled pipe: Outer diameter: >38～630; Wall thickness: 3～80; Common specifications: 42×4, 50×5, 89×6, 108×4.5, 133×7, 159×6, 219×6, 273×8, 325×8.5

  Cold-drawn (cold-rolled) pipe: Outer diameter: 6～720; Wall thickness: 0.25～120; Common specifications: 22×2.5, 25×2.5, 32×3, 38×4, 45×3

  Common standards and materials:

  Standards: GB/T 8162 (for structural use), GB/T 8163 (for fluid transport);

  Materials: 10#, 20#, 35#, 45#, 16Mn, etc.

  When purchasing, the following must be specified: the applicable standard, the intended use, the outer diameter, the wall thickness, and the tolerances.

  
  

  1. Small-diameter seamless steel pipes

  Outer diameter range: 6 mm~108 mm

  Common outer diameter specifications: 6, 8, 10, 12, 14, 16, 18, 20, 25, 32, 38, 42, 45, 48, 51, 57, 60, 76, 89, 108mm

  Wall thickness range: 1 mm~12 mm

  Applications: Primarily used for conveying fluids (such as water, gas), mechanical structural parts (such as automotive drive shafts), instrument conduits, etc.

  2. Medium-diameter seamless steel pipes

  Outer diameter range: 114 mm~325 mm

  Common outer diameter specifications: 114, 133, 140, 159, 168, 180, 219, 273, 325mm

  Wall thickness range: 4 mm~25 mm

  Application scenarios: Mainly used for oil pipelines, natural gas transportation, heat pipelines, and large mechanical structure support, etc.

  3. Large-diameter seamless steel pipes

  Outer diameter range: 351mm and above

  Common outer diameter specifications: 351, 402, 426, 450, 508, 610mm, etc.

  Wall thickness range: 6 mm- 50 mm (some special applications can be thicker)

  Application scenarios: Suitable for high-pressure pipelines (such as power plant steam pipelines), pressure vessels, marine engineering, bridge construction, etc.

  
  
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  After I place an order and it enters the production process, can I get real-time updates on the production progress, quality inspection status, and other information about the steel?

  Hello, thank you for your message. Of course, you can. Once an order is placed and enters the production process, you can contact the person in charge, who will update you in a timely manner. However, please note that we provide real-time synchronization at the node level, rather than a live broadcast of every process on the factory floor.

  The specific information that can be obtained includes: firstly, synchronization by node: production scheduling confirmation, raw material arrival, completion of key processes, and completion pending inspection, etc.

  We can provide batch-by-batch factory test certificates, third-party inspection reports from platforms at key stages, on-site photos/videos, completion inspection results, and records of handling anomalies.

  After container loading, we can provide the container number, bill of lading number, vessel name and voyage number, and synchronize key milestones such as customs declaration, departure, and arrival at the port; the logistics track is based on the data of the shipping company and port, and there may be normal information delays.

  
  
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  If we purchase steel bars in bulk through your platform, do you accept third-party re-inspection? At what frequency should mechanical properties and chemical composition be sampled?

  The platform fully accepts and supports third-party re-inspection of steel bars purchased in bulk. This is a routine and important step in ensuring the quality and fairness of bulk steel transactions.

  The sampling frequency for third-party re-inspection follows the industry standard of "batch inspection, with 60 tons as the base and additional samples for quantities exceeding 40 tons". Chemical composition is mainly determined according to the furnace/tank number, while mechanical properties are sampled incrementally as the batch size increases. The platform accepts third-party re-inspections. The specific sampling and testing procedures can be further confirmed with the platform or your designated third-party testing agency during the order execution stage.