Black steel pipe is a type of carbon steel pipe made from carbon steel or low-alloy steel as the base material. After hot rolling or cold rolling, a black iron oxide layer is formed on the surface. It is high-strength, easy to weld, and cost-effective. It is available in two main categories: seamless steel pipe and welded steel pipe, and is used in industrial and infrastructure fields.
Glory Steel is a high-quality black steel pipe manufacturer in China, specializing in manufacturing Q235/ASTM A53 black steel pipe in sizes SCH 20-SCH 80 for water supply and drainage, gas transmission, and structural support. Square, round, and rectangular cross-sections are available, and custom orders are accepted.
Specification
| Item | Black Steel Pipe |
| Place of Origin | Tianjin, China |
| Standard | GB/T 8162, GB/T 8163, ASTM A53, API 5L |
| Steel Grade | Q235B, ASTM A53 Grade B, API 5L Grade B |
| Shape | Round, Square, Rectangular |
| WT | 1.65-20mm |
| Outer Diameter | 1/2″ – 24″ (DN15 – DN600) |
| Length | 6-12m |
| Technique | ERW/SSAW/LSAW, Seamless |
Chemical Composition
| Grade | Q235B | Q345B | 20# steel | ASTM A53 Gr.B |
|---|---|---|---|---|
| C | ≤0.20 | ≤0.20 | 0.17 – 0.24 | ≤0.30 |
| Si | ≤0.30 | ≤0.55 | 0.17 – 0.37 | ≤0.30 |
| Mn | 1.20 – 1.60 | 1.00 – 1.60 | 0.35 – 0.65 | 0.29 – 0.90 |
| P | ≤0.045 | ≤0.035 | ≤0.035 | ≤0.050 |
| S | ≤0.045 | ≤0.035 | ≤0.035 | ≤0.045 |
| Base | Fe | Fe | Fe | Fe |
Mechanical Properties
| Grade | Yield strength (MPa) | Tensile strength (MPa) | Elongation (%) | Brinell hardness (HB) |
|---|---|---|---|---|
| Q235B | ≥235 | 370-500 | ≥26 | 120-150 |
| Q345B | ≥345 | 470-630 | ≥21 | 140-180 |
| 20# steel | ≥245 | 410-550 | ≥25 | 130-160 |
| ASTM A53 Gr.B | ≥240 | 415-550 | ≥20 | 130-160 |
Application scenarios
Industrial Pipelines
Oil transport pipes, black steel gas pipes, fluid transport in chemical plants, and frames for mining and machinery equipment.
Building and Infrastructure
Black hot-dip plastic-coated steel pipes are used for cable protection, scaffolding, steel structure columns, bridge supports, warehouse racking, and drainage protection pipes.
Energy Transmission
Used as a functional pipe layer in heating systems, combined with insulation layers and plastic pipes to form “black jacket insulated pipes,” and also for solar panel supports, etc.
Key Advantages
- High Strength: Suitable for high-pressure and high-temperature environments, such as industrial fluids and fire-fighting pipelines, with excellent tensile and yield strength.
- Excellent Machinability: Can be easily cut, bent, welded, and drilled. Post-processing options include painting, hot-dip plastic coating, or galvanizing to enhance corrosion resistance.
- Economical and Practical: Lower cost compared to stainless steel or galvanized pipes, making it a cost-effective choice for structural support.
- Highly Customizable: Supports customized outer diameter, wall thickness, and length; can be threaded, beveled, and other end treatments.
Common classifications
By Process
- Seamless pipe: High strength, no weld seams, suitable for high-pressure environments.
- Welded pipe: Low cost, suitable for general applications such as construction scaffolding and structural frames.
By Section
Round tubes, square tubes (black square tubes), rectangular tubes
Welded black steel pipe VS Seamless black steel pipe
| Dimensions | Seamless black iron pipe | Welded black iron pipe |
| Raw Materials | Carbon steel bar (round steel billet) | Cold-rolled/hot-rolled steel strip |
| Process | No weld seam | With welds |
| Pressure Bearing Capacity | High quality | Medium |
| Wall Thickness Grade | Full range | Mainstream SCH 20/40/80 |
| Representative Material | ASTM A53 Grade B, API 5L Grade B, Q235B | ASTM A53 Grade B, Q235B |
| Cost | High quality | Lower grade |
SCH Steel Pipe Specification
| Size | OD | SCH 20 | SCH 40 | SCH 60 | SCH 80 |
|---|---|---|---|---|---|
| 1/2″ (DN15) | 21.3 mm | 2.1 mm | 2.8 mm | — | 3.6 mm |
| 3/4″ (DN20) | 26.9 mm | 2.1 mm | 2.9 mm | — | 3.9 mm |
| 1″ (DN25) | 33.7 mm | 2.4 mm | 3.4 mm | — | 4.5 mm |
| 1 1/4″ (DN32) | 42.4 mm | 2.8 mm | 3.6 mm | — | 5.0 mm |
| 1 1/2″ (DN40) | 48.3 mm | 2.8 mm | 3.7 mm | — | 5.2 mm |
| 2″ (DN50) | 60.3 mm | 3.2 mm | 3.9 mm | 5.2 mm | 5.5 mm |
| 2 1/2″ (DN65) | 76.1 mm | 3.6 mm | 5.2 mm | 6.0 mm | 7.1 mm |
| 3″ (DN80) | 88.9 mm | 4.1 mm | 5.5 mm | 6.6 mm | 7.6 mm |
| 4″ (DN100) | 114.3 mm | 5.2 mm | 6.0 mm | 7.1 mm | 8.6 mm |
| 6″ (DN150) | 168.3 mm | 7.1 mm | 7.1 mm | 9.5 mm | 11.0 mm |
| 8″ (DN200) | 219.1 mm | 7.1 mm | 8.2 mm | 10.3 mm | 12.7 mm |
Factory advantages
- Factory Direct Supply: Years of professional production experience, no middlemen, direct production and sales, making prices more competitive.
- In-Stock Inventory: Regularly stocked SCH 40/SCH 80 specifications, allowing for quick response to small batch orders.
- Fast Delivery: Regular orders ship within 15–30 days, urgent orders can be prioritized for production.
- Flexible Customization: Supports small batch trial orders (minimum 5 tons), accepting specifications for length, material, wall thickness, etc.
cooperative projects
FAQs
Glory Steel factory, located in Tianjin, China, is an ISO 9001 certified factory with an annual output of 100,000 tons. We specialize in seamless black steel pipe, ERW/SSAW black pipe, and threaded black steel pipe, with hot-selling sizes including 2 inch, 3/4 inch, and 4 inch, for water, gas, and oil projects. With our high-quality products and services, we export to over 120 countries.
Mon-Fri: 8:00 – 18:00 (GMT+8)
