Production Standard | Chemical Composition | Physical & Mechanical Properties
Metal pipe — is a hollow cylindrical round metal product made of carbon steel. It is widely used in industry, construction, and public utilities. According to the production method, pipes are divided into 3 types: welded, seamless, and furnace-welded pipes.
Production Standard:
- GOST 8731/32 — seamless pipe
- GOST 10704/05 — welded pipe
Chemical Composition (%):
- St3, St20, St37
- S235, S275 (according to EN standard)
| Element | Percentage (%) | Effect |
|---|---|---|
| Carbon (C) | 0.17-0.24 | Strength and hardness |
| Manganese (Mn) | 0.35-0.70 | Strength, impact resistance |
| Silicon (Si) | 0.17-0.37 | Elasticity |
| Phosphorus (P) | ≤ 0.035 | Increases brittleness if elevated |
| Sulfur (S) | ≤ 0.035 | Impairs weldability |
| Iron (Fe) | Remainder | Main base |
Mechanical Properties:
| Property | Seamless | Welded |
|---|---|---|
| Tensile strength | 410-550 MPa | 370-510 MPa |
| Yield strength | 245-355 MPa | 215-315 MPa |
| Elongation | ≥ 20-25 % | ≥ 18-22 % |
| Impact resistance | High | Moderate |
| Pressure resistance | Very high | Moderate-high |
| Feature | Seamless | Welded |
|---|---|---|
| Chemical composition | Same | Same |
| Structure | Homogeneous | Welded seam |
| Mechanical strength | Higher | Slightly lower |
| Pressure resistance | Very high | Moderate-high |
| Price | Expensive | Cheaper |
| Safety | Maximum | Standard dependent |
Physical Properties:
| Property | Seamless | Welded |
|---|---|---|
| Density | ≈ 7850 kg/m³ | ≈ 7850 kg/m³ |
| Melting point | 1450-1520 °C | 1450-1520 °C |
| Thermal conductivity | 45-60 W/m·K | 45-60 W/m·K |
| Linear thermal expansion | (11-13) x 10⁻⁶ 1/°C | (11-13) x 10⁻⁶ 1/°C |
| Electrical conductivity | Good | Good |
| Magnetic property | Magnetic | Magnetic (ferromagnetic) |
| Heat capacity | 460-500 J/kg·K | 460-500 J/kg·K |
| Corrosion resistance | Moderate (coating required) | Moderate (external coating required) |
| Physical durability | High, more durable due to being seamless | Seam area may be sensitive to load and pressure |
Application Areas | Advantages | Limitations | Terms of Sale
Application Areas:
-
Seamless Pipe
- High-pressure oil and gas pipelines
- Steam and boiler systems
- Power generation (power plants)
- Petrochemical and chemical industry
- Hydraulic and pneumatic systems
- Aviation and mechanical engineering
- High-temperature lines
-
Welded Pipe
- Water and sewage lines
- Low and medium pressure gas systems
- Construction and metal structures
- Heating and ventilation (HVAC)
- Industrial pipelines
- Oil and gas distribution lines
- Fence, post, and frame systems
Advantages:
-
Seamless Pipe
- No weak points since there is no seam
- Resistant to very high pressure and temperature
- Homogeneous metal structure
- Long-term and safe operation
- High impact and fatigue resistance
- Reliable in cryogenic and high-temperature environments
-
Welded Pipe
- Cheaper and more economical
- Easily produced in large diameters
- Wide range of sizes and thicknesses
- Easy to find and fast to procure
- Seam strength is high in modern ERW technology
- Convenient installation
Limitations:
-
Seamless Pipe
- Expensive price
- Difficult to find in large diameters
- Complex and energy-intensive production
- Limited size and thickness options
- Procurement lead times can be long
-
Welded Pipe
- Welded seam is a potential weak point
- Limited for high pressure and temperature
- Lower impact and fatigue resistance than seamless
- Corrosion can start faster in the seam zone
- Restricted use in critical safety applications
Terms of Sale:
- Pipe price is determined by size, thickness, and type (welded, seamless). Prices are quoted per meter.
- Pipe demand is passed as quantity (pieces), pipe length is 6m or 12m for welded, and 7.85m for seamless.
- Relevant documents are provided to the buyer upon request (contract, acceptance act, invoice, waybill, weight slip, cash receipt, laboratory test analysis, certificate, etc.).
