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ASTM A671 CB70
keyword ASTM A671 CB70 Category Steel pipe material Related products Get a quoteTechnical Specification and Product Characteristics of ASTM A671 CB70 Spiral Steel Pipe
1、 Standard and Level Definition
Execution standard: ASTM A671 is an electric fusion welding (EFW) steel pipe standard, suitable for medium and low temperature (-29 ℃~+343 ℃) high-pressure pipeline systems. CB70 is a carbon manganese steel grade with a small yield strength of 70 ksi (approximately 483 MPa).
Grade characteristics: CB70 steel grade combines high strength and low temperature toughness, suitable for spiral submerged arc welding forming process, with an outer diameter usually ≥ 400mm and a wall thickness ≥ 6.4mm.
2、 Chemical composition and mechanical properties
Chemical composition
Basic elements: carbon (C) ≤ 0.30%, manganese (Mn) 0.60-1.35%, sulfur (S) ≤ 0.035%, phosphorus (P) ≤ 0.035%, optimize welding performance.
Alloy control: Low sulfur and phosphorus design reduces cold brittleness and enhances low-temperature environmental adaptability.
Mechanical performance
Yield strength: ≥ 483 MPa (70 ksi).
Tensile strength: ≥ 483-621 MPa (70-90 ksi).
Low temperature toughness: optional -46 ℃ impact test (additional requirements such as CL22 grade need to be specified).
3、 Production process and testing requirements
Manufacturing process
Spiral forming: using hot-rolled steel strip spiral winding, the weld seam is formed by double-sided submerged arc welding (SAW) process, and the weld seam is uniform.
Post weld treatment: Stress relief heat treatment is required to prevent cold cracking and enhance weld strength.
Quality control
Non destructive testing: The weld seam requires 100% ultrasonic testing (UT) or X-ray sampling, in accordance with ASTM A435 standard.
Dimensional tolerance: Outer diameter error ≤ ± 0.75%, wall thickness deviation -5%~+10%.
4、 Application Fields and Typical Specifications
Core scenario:
High pressure oil and gas transmission pipelines and chemical equipment (such as reactor and heat exchanger pipelines).
Nuclear power auxiliary systems and industrial pipelines in low-temperature environments (-46 ℃).
High pressure pipelines for power boilers (applicable temperature ≤ 343 ℃).
Typical specifications:
Outer diameter: Φ 400- Φ 3620 mm.
Wall thickness: 8-50 mm (conventional thickness 10-25 mm).
5、 Certification and selection recommendations
Certification documents: ASTM standard material certificate (including measured data on chemical composition and mechanical properties) and non-destructive testing report are required.
Selection precautions:
Low temperature scenarios require clear additional requirements for impact testing (such as CL22 grade).
It is recommended to add anti-corrosion coatings (such as epoxy coatings or 3PE) in highly corrosive environments.
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