I. Overview of BS 6323 Seamless Steel Pipes
BS 6323 seamless steel pipes are high-precision seamless steel pipes manufactured according to the British standard BS 6323. They are widely used in mechanical engineering, industrial fluid transportation, high-pressure steam pipelines, and hydraulic systems.
This standard covers seamless pipes made of carbon steel and low-alloy steel, suitable for high-temperature, high-pressure, and precision machining environments, ensuring dimensional accuracy and stable mechanical properties of the pipes.
Product Features
- Precise dimensions: Strict control of outer diameter, wall thickness, and length tolerances.
- Reliable mechanical properties: Stable yield strength, tensile strength, and elongation.
- Multiple steel grades available: Carbon steel (CFS3/CFS4) is suitable for medium and low pressure applications, while low-alloy steel (16Mo3/13CrMo44) is suitable for high-temperature and high-pressure applications.
- Optional surface treatments: Bright finish, hot-rolled, galvanized, or coated with anti-rust oil.
- Wide range of applications: Mechanical pipelines, hydraulic systems, high-pressure steam pipes, and structural support.
II. Common Steel Grades and Materials of BS 6323 Seamless Steel Pipes
| Steel Grade / Material | Type | Key Features | Typical Applications |
|---|---|---|---|
| CFS 3 | Carbon Steel | Moderate strength, good plasticity and workability, excellent weldability | General mechanical structural tubes, low- to medium-pressure fluid pipelines |
| CFS 4 | Carbon Steel | Higher strength than CFS 3, better load-bearing capacity | Mechanical engineering, high-load structural piping |
| 16Mo3 | Low Alloy Steel | Good high-temperature performance, strong creep resistance | High-temperature steam pipelines, boilers, heat exchanger systems |
| 13CrMo4-5 / 13CrMo44 | Low Alloy Steel | Excellent high-temperature and high-pressure performance, superior overall mechanical properties | Power plants, chemical industry, high-temperature high-pressure industrial pipelines |
| E355 (equivalent) | High-Strength Structural Steel | High strength, good dimensional accuracy (commonly used for equivalence) | Precision machinery, hydraulic systems, engineering equipment |
Selection Tips:
- For general mechanical and fluid applications: Prioritize CFS 3 / CFS 4, which offer good value for money.
- For high-temperature or high-pressure conditions: 16Mo3 or 13CrMo series are recommended.
- For applications requiring high dimensional accuracy: Cold-finished steel pipes are recommended.
III. BS 6323 Seamless Steel Pipe Chemical Composition and Mechanical Properties
i. Chemical Composition of BS 6323 Seamless Steel Pipes
| Steel Grade | C (%) | Mn (%) | Si (%) | P ≤ (%) | S ≤ (%) | Cr (%) | Mo (%) |
|---|---|---|---|---|---|---|---|
| CFS 3 | ≤0.20 | 0.60–1.20 | ≤0.35 | 0.045 | 0.045 | — | — |
| CFS 4 | ≤0.25 | 0.80–1.40 | ≤0.35 | 0.040 | 0.040 | — | — |
| 16Mo3 | ≤0.16 | 0.40–0.90 | ≤0.35 | 0.025 | 0.020 | ≤0.30 | 0.25–0.35 |
| 13CrMo4-5 / 13CrMo44 | 0.10–0.18 | 0.40–0.70 | ≤0.35 | 0.025 | 0.020 | 0.70–1.15 | 0.40–0.60 |
| E355 (for equivalence) | ≤0.22 | ≤1.60 | ≤0.55 | 0.025 | 0.025 | — | — |
ii. BS 6323 Seamless steel pipe mechanical properties
| Steel Grade | Yield Strength ≥ (MPa) | Tensile Strength (MPa) | Elongation ≥ (%) | Impact Performance (Reference) |
|---|---|---|---|---|
| CFS 3 | 235 | 410–530 | 22% | Pass at room temperature |
| CFS 4 | 275 | 440–600 | 20% | Pass at room temperature |
| 16Mo3 | 280 | 450–600 | 22% | Pass at 20°C |
| 13CrMo4-5 / 13CrMo44 | 300 | 450–650 | 20% | Optional at 20°C / 0°C |
| E355 (for equivalence) | 355 | 490–630 | 22% | Optional at −20°C |
IV. BS 6323 Seamless Steel Pipe Temperature and Pressure Rating Selection Table
| Steel Grade | Applicable Temperature Range (℃) | Typical Working Pressure Range* | Suitable Operating Conditions |
|---|---|---|---|
| CFS 3 | −20 to 300 | ≤ 10 MPa | General mechanical structures, low-pressure fluids, equipment piping |
| CFS 4 | −20 to 350 | ≤ 16 MPa | Medium-load structures, medium-pressure industrial pipelines |
| 16Mo3 | −20 to 530 | ≤ 25 MPa | High-temperature steam, boiler pipes, heat exchange systems |
| 13CrMo4-5 / 13CrMo44 | −20 to 580 | ≤ 32 MPa | High-temperature and high-pressure applications, power plants, chemical plants |
| E355 (reference) | −40 to 400 | ≤ 20 MPa | Precision machinery, hydraulic systems, high-strength pipelines |
Quick Selection Guide
- Ambient temperature + Low pressure (≤10 MPa)
Choose CFS 3, offering excellent cost-effectiveness. - Ambient temperature + Medium pressure (10–16 MPa)
Choose CFS 4, offering higher load-bearing capacity. - High-temperature applications (>350℃)
16Mo3 or 13CrMo4-5 are mandatory. - Long-term high-temperature + high-pressure operation
13CrMo4-5 / 13CrMo44 are preferred. - High requirements for dimensional accuracy and strength
E355 (cold-worked) is an option.
