What is A671 CC60 Material
ASTM A671 is a standard for electric-fusion-welded steel pipes established by the American Society for Testing and Materials (ASTM), specifically intended for carbon steel and alloy steel pipelines used in low-temperature environments. The designation "CC60" represents the chemical composition category and mechanical property grade of the steel pipe. According to the standard requirements, steel pipes of the CC60 grade must meet the following key indicators:
Chemical Composition: The carbon content is controlled below 0.30%, with manganese content ranging from 1.00% to 1.60%. Trace alloying elements such as nickel and chromium are included to enhance low-temperature toughness. Harmful elements like phosphorus and sulfur are strictly limited (P ≤ 0.025%, S ≤ 0.025%).
Mechanical Properties: The minimum yield strength is 415 MPa (60 ksi), the tensile strength ranges from 485 to 760 MPa, and the elongation is ≥ 20%. A low-temperature impact energy requirement of ≥ 27 J at -46°C ensures resistance to brittle fracture in cold environments.
Dimensional Tolerances: The allowable deviation for the outer diameter is ±0.75%, the wall thickness deviation is -10%/12.5%, and the straightness deviation shall not exceed 3 mm per 3 meters.
Production Process Flow
ASTM A671 CC60 longitudinally welded steel pipes are manufactured using high-frequency resistance welding (ERW) or submerged arc welding (SAW) processes. The main production process includes:
Plate Preprocessing: Steel plates conforming to standards such as ASTM A516 Gr60 are selected and subjected to ultrasonic flaw detection testing. Edge milling is then performed to ensure welding groove precision.
Forming and Welding: The steel plates are cold-bent into a tubular shape using a JCOE or UOE forming machine. Multi-wire submerged arc welding is employed for longitudinal seam welding, with strict control over heat input (typically maintained at 25-35 kJ/cm).
Weld Treatment: After welding, internal and external burrs are removed. Online heat treatment (such as normalizing) is applied to eliminate welding residual stresses. For some applications with stringent requirements, full-pipe quenching and tempering treatments are also conducted.
Non-destructive Testing: 100% ultrasonic testing (UT) and eddy current testing (ET) are performed, along with X-ray real-time imaging testing (RT) on the welds, achieving a defect detection sensitivity of 0.5 mm.
Hydrostatic Testing: The test pressure is calculated according to a standard formula (P = 2St/D), with a pressure holding time of not less than 10 seconds to ensure pressure-bearing capacity.
Test and inspection
Third-Party Inspection: It usually requires certification from agencies such as BV, SGS, etc., covering:
Chemical analysis: Detection of all elements using direct-reading optical emission spectrometer (OES).
Mechanical tests: -60°C low-temperature impact test and hardness gradient test.
Corrosion test: HIC (hydrogen-induced cracking) resistance test in accordance with NACE TM0177 standard.
Documentation Requirements: Each batch of steel pipes shall be accompanied by the Material Test Certificate (MTC), third-party inspection report (e.g., 3.1/3.2 certificate), Non-Destructive Testing (NDT) report, and heat treatment curve records.
A671 CC60 EFW Pipe Factory
