Material, Dimensions, and Production Details for No. 10 Seamless Steel Pipe

First, Material Standards and Specifications for No. 10 Seamless Steel Pipe

According to the national standards GB/T 8162-2018 "Seamless Steel Pipe for Structural Use" and GB/T 9948-2025 "Seamless Steel Pipe for Petrochemical and Chemical Plants," No. 10 seamless steel pipe is a high-quality carbon structural steel. The "10" in its designation represents a carbon content of 0.07%-0.14%. The standard outer diameter range for this type of pipe is 10-426mm, with a wall thickness of 1.5-36mm. Common sizes range from Φ25-159mm. For example, a typical size of No. 10 seamless steel pipe produced by hot rolling, such as Φ89mm × 4.5mm, has a theoretical weight of 9.38kg/m, a tensile strength of≥335MPa, a yield strength of≥205MPa, and an elongation of≥24%. Precision machinery models adhere to the higher standard of GB/T 3639, with dimensional tolerances within ±0.05mm. It's worth noting that the market uses two different designations, "No. 10" and "10#," which, upon verification, represent different designations for the same material. When purchasing, users should carefully distinguish between similar grades in international standards such as ASTM A106, as their chemical composition and mechanical properties can differ slightly. Thick-walled models (wall thickness > 20mm) often use European standard materials such as S355J2H, suitable for high-pressure applications.

Second, Production Process and Key Technical Points for No. 10 Seamless Steel Pipe

1. Hot Rolling Process: Round billet → Heating in a ring furnace to 1250°C → Forming in a piercing mill → Extension on a continuous rolling mill → Calibration on a sizing mill → Straightening → Eddy current testing → Cutting → Heat treatment. Key control points are the service life of the piercing plug (typically 300-400 pieces/piece) and the rolling temperature fluctuation range (±20°C). 2. Cold Drawing Precision Processing: After pickling and phosphating, the hot-rolled tube undergoes multiple cold drawing passes (deformation 15%-25%/pass) to achieve IT8-IT10 precision. Seamless steel tubes for precision machinery require an additional spheroidizing annealing process (720°C ± 10°C for 4 hours) to achieve a hardness between 140 and 170 HB.

3. Quality Control System: This includes online ultrasonic thickness measurement (accuracy ±0.1mm), fully automatic water pressure testing (test pressure ≤ 20 MPa), and spectral component analysis. Especially for fluid transportation applications, 100% eddy current testing is required, with a defect detection sensitivity of 0.8mm flat-bottom holes.

Third, Analysis of Typical Application Scenarios for No. 10 Seamless Steel Pipe

1. Energy Sector: Used as furnace tubes in petroleum cracking units (operating temperature ≤ 450°C), requiring use with heat-resistant steels such as 12CrMoVG. A case study of an oilfield steam injection boiler project shows that using Φ114×16mm pipes has a service life more than three times longer than that of ordinary welded pipes.

2. Machinery Manufacturing: Hydraulic cylinder barrels should use precision cold-drawn steel pipes (e.g., Φ50×5mm), with an inner surface roughness of Ra0.8μm. Test data from a construction machinery company shows that cylinders made from No. 10 seamless steel pipes have a 40% higher pressure resistance than ordinary pipes.

3. Building Structures: When using Φ219×10mm pipes for large-span stadium trusses, normalizing treatment (900°C air cooling) is required to ensure weldability. Actual measurements at a Shenzhen sports center project show that the impact energy of heat-treated pipe welds reaches 54J (at -20°C). 4. Special Applications: Thick-walled pipes for chemical equipment (e.g., Φ325×30mm) require a -46°C Charpy impact test; pipes for nuclear power plants require controlled residual content of elements such as copper and cobalt (Cu ≤ 0.10%, Co ≤ 0.02%).

Fourth, Key Points for Selecting and Decision-Making No. 10 Seamless Steel Pipe

1. Parameter Matching Principle: When calculating wall thickness based on operating pressure, refer to the ASME B31.3 formula: t = PD / (2SE + 0.8P), where the design pressure P is 1.5 times the operating pressure. For example, for a Φ89mm steel pipe under 6MPa operating conditions, the calculated minimum wall thickness is 3.2mm; the actual specification should be 4.5mm.

2. Cost Optimization Strategy: When purchasing in bulk for sizes below Φ159mm, hot-rolled steel pipes offer 15%-20% cost savings over cold-drawn steel pipes. For non-pressure-bearing structural components, consider using GB/T 8163 fluid pipes instead of GB/T 8162 structural pipes. 3. Supplier Evaluation Criteria: Focus on mill configuration (such as whether it is equipped with a three-roll limited-motion mandrel continuous mill), quality assurance system (whether it has API 5L certification), and case studies (whether it has CNPC Class A supplier qualification).

Fifth, Industry Development Trends for No. 10 Seamless Steel Pipe

1. Material Upgrade: Some companies have developed improved steel grades in the BX10 series, which increase yield strength to 345 MPa by adding trace amounts of niobium (0.02%-0.05%).

2. Smart Production: A Shandong steel mill implemented an MES system that increased the yield rate of No. 10 seamless steel pipe from 87% to 92%. The heating furnace combustion model was optimized through big data analysis.

3. Green Manufacturing: The emerging pickling-free process uses mechanical dephosphorization instead of traditional pickling, reducing waste acid emissions by 0.15 m³ per ton of product. This process is currently being piloted at some companies in Jiangsu.