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GOST 8734-75 defines the dimensional and technical requirements for cold-formed seamless steel pipes, covering products with an outer diameter from 1 mm to 200 mm and a wall thickness from 0.2 mm to 22 mm.
The cold-forming process provides high-dimensional precision, an improved surface finish, and enhanced mechanical strength, making these pipes suitable for applications requiring tight tolerances and reliable performance.
During manufacturing, the outer diameter and wall thickness are strictly controlled. Upon customer request, the inner diameter and wall thickness variation can also be taken into account. The maximum deviations for internal-diameter do not exceed those allowed for the external diameter. For pipes of 10 mm or smaller in diameter, tolerances are determined by agreement between the manufacturer and the customer.
Ovality and wall thickness variation must remain within the specified tolerances for outer diameter and wall thickness.
Pipe curvature per 1 meter of length shall not exceed:
3 mm for pipes 5–8 mm in diameter
2 mm for pipes 8–10 mm in diameter
1.5 mm for pipes over 10 mm in diameter
At the customer’s request, curvature for pipes 20–90 mm in diameter can be limited to 1 micron per meter.
Chemical Composition
C (%) | Si (%) | Mn (%) | P (%) | S (%) | Cr (%) | Ni (%) | Cu (%) |
0.07–0.14 | 0.17–0.37 | 0.35–0.65 | ≤0.025 | ≤0.030 | ≤0.15 | ≤0.30 | ≤0.30 |
Mechanical Properties
Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |
≥343 | ≥206 | ≥24 |
Outside Diameter & Tolerance
Outside Diameter (mm) | Tolerance (mm) |
5 ≤ OD ≤ 10 | ±0.15 |
10 < OD ≤ 30 | ±0.30 |
30 < OD ≤ 50 | ±0.40 |
OD > 50 | ±0.8% |
Wall Thickness & Tolerance
Wall Thickness (mm) | Tolerance |
WT ≤ 1 | ±0.12 mm |
1 < WT ≤ 5 | ±10% |
WT > 5 | ±8% |
1 < WT ≤ 2.5, OD > 110 | ±12.5% |
Advantages of GOST 8734-75 Steel Pipes
1. High Dimensional Accuracy: Cold deformation ensures precise tolerances, making the pipes ideal for high-precision mechanical, hydraulic, and pneumatic systems.
2. Smooth Inner Surface: Reduced internal roughness lowers fluid resistance, improving performance in flow-sensitive applications.
3. Reliable Mechanical Strength: Adequate tensile and yield strength ensure suitability for pressure-bearing and structural uses.
4. Wide Range of Specifications: Available in numerous diameters and wall thickness combinations to meet diverse engineering and design requirements.
Applications of GOST 8734-75 Steel Pipes
1. Oil and gas transmission systems (low to medium pressure)
2. Heat exchangers and condenser units
3. Machinery and automotive components
4. Hydraulic and fuel line systems
5. Industrial and general-purpose piping
Hunan Gaoxing Steel Development Zone, No.1888 Purui South Rd, Wangcheng District,Changsha, Hunan, China
Tel: 0086-0731-88678598
