In offshore and subsea engineering, the reliability and corrosion resistance of pipelines directly affect project safety and service life. Under extreme conditions such as high salinity, high pressure, and strong corrosive environments, ASTM A671 steel pipe demonstrates excellent mechanical performance, chemical stability, and consistent weld quality. This article provides an in-depth analysis of ASTM A671 pipes’ mechanical properties, chemical composition, testing standards, and application advantages, while showcasing LONGMA’s production and inspection capabilities.
ASTM A671 Standard and Marine Engineering Suitability
ASTM A671 is an Electric-Fusion-Welded (EFW) steel pipe standard developed by ASTM International, primarily used for pressure and high-temperature service. The pipes are available in different grades: CC60, CC65, and CC70.
| Grade | Tensile Strength (MPa) | Yield Strength (MPa) | Typical Applications |
| ASTM A671 CC60 | 415–550 | 240–310 | Medium- and low-pressure subsea pipelines |
| ASTM A671 CC65 | 450–585 | 275–355 | Mid-depth offshore oil & gas systems |
| ASTM A671 CC70 | 485–620 | 310–415 | Offshore platform high-pressure main lines |
Summary:
- CC60 is suitable for systems with high workability requirements.
- CC65 balances strength and toughness, making it the most commonly used grade.
- CC70 provides maximum strength for high-pressure and high-temperature marine conditions.
Mechanical Properties and Chemical Composition
- Mechanical Properties Comparison
| Property | Test Standard | CC60 | CC65 | CC70 |
| Tensile Strength (MPa) | ASTM A370 | 415–550 | 450–585 | 485–620 |
| Yield Strength (MPa) | ASTM A370 | ≥240 | ≥275 | ≥310 |
| Elongation (%) | ASTM A370 | ≥20 | ≥18 | ≥18 |
| Impact Energy (J) | ASTM E23 | ≥27 | ≥27 | ≥30 |
Conclusion:
ASTM A671 pipes exhibit excellent tensile strength, yield strength, and low-temperature toughness, ensuring structural stability under deep-sea high-pressure conditions.
- Chemical Composition Table
| Element | Range (%) | Function |
| Carbon (C) | 0.24–0.30 | Increases strength and hardness |
| Manganese (Mn) | 0.70–1.35 | Enhances toughness and impact resistance |
| Silicon (Si) | 0.15–0.50 | Improves oxidation and corrosion resistance |
| Phosphorus (P) | ≤0.035 | Reduces brittleness |
| Sulfur (S) | ≤0.035 | Minimizes cracking and lamination defects |
Typical Grades:
ASTM A671 CC60 Class 22 and ASTM A671 CC65 CL22 are strictly controlled for chemical composition, ideal for subsea pipelines and high-humidity environments.
Comparison: ASTM A671 vs A672 and A691
| Feature | ASTM A671 | ASTM A672 | ASTM A691 |
| Manufacturing Process | EFW | EFW | EFW |
| Material Type | Carbon / Low Alloy Steel | Pressure Vessel Steel | Cr-Mo Alloy Steel |
| Suitable Environment | Medium- to high-pressure, corrosion-resistant | High-pressure steam systems | Ultra-high temperature & pressure |
| Common Grades | CC60 / CC65 / CC70 | CL20 / CL22 / CL25 | 1¼Cr-½Mo / 2¼Cr-1Mo |
| Cost Level | ★★★ | ★★★★ | ★★★★★ |
Analysis:
Considering strength, cost, and corrosion resistance, ASTM A671 pipe offers the best value for offshore engineering applications.
Testing and Quality Control
LONGMA applies comprehensive testing to every ASTM A671 steel pipe to ensure compliance with ASTM standards and client requirements.
| Test | Standard | Content | Purpose |
| Chemical Analysis | ASTM E415 | Elemental composition | Verify raw material quality |
| Tensile Test | ASTM E8/E8M | Tensile and yield strength | Ensure mechanical performance |
| Impact Test | ASTM E23 | Charpy V-notch impact energy | Confirm low-temperature toughness |
| NDT (UT/RT) | ASTM E213 / E309 | Weld defect detection | Ensure weld integrity |
| Hydrostatic Test | ASTM A530 | High-pressure sealing | Check leakage and pressure resistance |
In-house Laboratory:
LONGMA can issue full Material Test Certificates (MTCs) and third-party inspection reports, providing traceable quality assurance.
Typical Offshore Applications
| Application | Typical Use | Advantages |
| Subsea Pipeline Systems | Natural gas & oil transport | High pressure and corrosion resistance |
| Offshore Riser | Vertical lift pipes | Impact and fatigue resistance |
| Thermal & Condensate Systems | Heat exchange loops | Stable heat transfer |
| Chemical & Desalination Units | Corrosive fluid transport | High purity and long service life |
Summary:
ASTM A671 CC60 and CC65 pipes maintain stable operation under complex marine conditions, reducing maintenance frequency and total lifecycle costs.
LONGMA Brand Advantages
- Over 20 years of ASTM-standard pipe manufacturing experience
- High-precision EFW welding processensuring dense, uniform welds
- Full range coverage CC60–CC70, supporting custom wall thickness and lengths
- Certified to DNV, ABS, ISO9001, ready for global offshore projects
- Provides MTC + third-party inspection reports, guaranteeing traceable quality
Conclusion: A Reliable Choice for Offshore Challenges
Materials and manufacturing quality determine the success of offshore and subsea projects.
ASTM A671 steel pipe is an ideal solution for harsh marine environments due to its excellent mechanical properties, corrosion resistance, and welding stability.
LONGMA delivers high-quality ASTM A671 pipe, ensuring project safety, reliability, and long-term performance for global clients.
