ASTM A671 CB70 LSAW Pipe
ASTM A671 CB70 LSAW Pipe: Carbon Steel Grade for Pressure & Low-Temperature Service
Comprehensive material data for ASTM A671 CB70 longitudinal submerged arc welded (LSAW) pipe, made from ASTM A515 Grade 70 normalized carbon-silicon steel plate, including chemical composition, mechanical properties, thermal properties, international equivalents, and application guidance.
Plate forming (three-roll bending or UOE), double‑sided submerged arc welding, optional post-weld heat treatment (normalized as per grade requirement)
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ASTM A671 CB70 LSAW Pipe Introduction
ASTM A671 CB70 is a grade of electric-fusion-welded (EFW) steel pipe manufactured by the longitudinal submerged arc welding (LSAW) process, designed for atmospheric and lower-temperature service. The pipe is fabricated from plates conforming to ASTM A515/A515M Grade 70, a carbon-silicon steel intended for intermediate- and higher-temperature pressure vessel applications. The 'CB70' designation indicates that the plate material is A515 Grade 70 and the pipe is supplied in the normalized condition. This grade offers a good combination of medium tensile strength, ductility, and weldability, making it suitable for pipelines, pressure vessels, and structural components operating in moderate environments. The pipe is typically produced in OD sizes from 16 inches (406 mm) and above, with wall thicknesses up to several inches, depending on the plate availability.
ASTM A671 CB70 LSAW Pipe Chemical Composition
The chemical requirements below are those of the base plate standard ASTM A515/A515M Grade 70. Limits vary with plate thickness; values given are for plates ≤ 25 mm (1 in.), which is the most common for LSAW pipe. For heavier walls, maximum carbon and manganese may increase (see notes). All elements listed are as specified in the standard; no other elements are intentionally added.
| Element | Standard Value (wt.%) | Remarks |
|---|---|---|
| Carbon (C) | 0.31 max | For thickness ≤ 25 mm |
| Manganese (Mn) | 0.90 max | For thickness ≤ 25 mm |
| Phosphorus (P) | 0.025 max | Heat analysis |
| Sulfur (S) | 0.025 max | Heat analysis |
| Silicon (Si) | 0.15–0.40 | For Grade 70, all thicknesses |
ASTM A671 CB70 LSAW Pipe Thermal & Electrical Physical Properties
The following physical constants are representative of carbon steel similar to ASTM A515 Grade 70. Actual values may vary slightly with composition, microstructure, and temperature. These data are provided for design and modelling purposes and are not mandatory per the standard.
| Property | Typical Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20 °C |
| Elastic Modulus (E) | 200–210 | GPa | At room temperature |
| Shear Modulus (G) | 77–80 | GPa | Calculated from E and ν |
| Poisson's Ratio (ν) | 0.29 | – | At room temperature |
| Thermal Expansion (α) | 11.7 | 10⁻⁶/K | 20–100 °C range |
| Thermal Conductivity (λ) | 50 | W/(m·K) | At 100 °C |
| Specific Heat Capacity (Cp) | 460 | J/(kg·K) | At 20 °C |
| Electrical Resistivity (ρₑ) | 0.15–0.20 | µΩ·m | At 20 °C |
ASTM A671 CB70 LSAW Pipe Mechanical Properties
Mechanical properties are those of the base plate prior to welding, as required by ASTM A515/A515M Grade 70 in the normalized condition. The pipe standard ASTM A671 does not alter these minima. Values are for plate thickness ≤ 25 mm (1 in.). For heavier walls, tensile strength remains the same but elongation requirements increase slightly and yield strength may be lower; consult the full standard.
| Property | Required Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | 260 min | MPa | At room temperature, for thickness ≤ 25 mm |
| Tensile Strength (Rm) | 485–620 | MPa | At room temperature |
| Elongation (A, 8 in. / 200 mm) | 21 min | % | For thickness ≤ 25 mm |
| Elongation (A, 2 in. / 50 mm) | 27 min | % | For thickness ≤ 25 mm |
ASTM A671 CB70 LSAW Pipe Completely Equivalent Material Standards & Replaceable Grades
These standards designate exactly the same pipe grade and base material. Direct substitution is permitted within the scope of the respective specifications.
| Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASME SA-671 | CB70 | Identical to ASTM A671 CB70 (ASME Boiler & Pressure Vessel Code, Section II) |
| USA (plate) | ASTM A515/A515M | Grade 70 | Base plate standard for the pipe; same chemistry and mechanicals |
| USA (plate) | ASME SA-515/SA-515M | Grade 70 | Identical plate standard under ASME |
ASTM A671 CB70 LSAW Pipe Application Introduction
ASTM A671 CB70 LSAW pipe is primarily employed in systems that require a reliable, weldable carbon steel with moderate tensile properties and good ductility at ambient and moderately low temperatures. The normalized condition ensures consistent mechanical behaviour and facilitates subsequent fabrication.
Product Applications: Long‑distance oil and gas transmission pipelines, Pressure vessel shells and storage tanks, Boiler drums and headers, Water‑injection and process piping headers, Structural columns and caissons for offshore platforms
Processed into products: Pipe spools and fittings (elbows, reducers, tees) for ASME B31.3 process piping, Manhole assemblies and nozzle necks on pressure vessels, Expansion loops and pig‑launcher/receiver barrels, Piling sleeves and jacket legs in offshore structures, Crossover spools between vessels in refining units
Application industries: Oil & gas (upstream and midstream pipeline networks), Petrochemical and chemical processing plants, Power generation (boilers, heat recovery steam generators), Water treatment and desalination facilities, Structural and mechanical engineering
ASTM A671 CB70 LSAW Pipe Similar / Closely Related Substitute Materials
The following materials have comparable strength, chemistry, and service temperature range. They may be considered for replacement after engineering evaluation, especially for pressure vessel and piping applications.
| Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A671 | CC70 | Same pipe type, plate from A516 Grade 70 (fine‑grain killed, better notch toughness) |
| USA | ASTM A672 | B70 | EFW pipe for high‑pressure at moderate temperatures, same A515 Grade 70 plate, different welding/post-weld heat treatment |
| Japan | JIS G3103 | SB480 | Boiler and pressure vessel plate; similar tensile (480‑620 MPa) and yield (≥275 MPa), close composition; used for vessels and pipes |
| India | IS 2002 | Grade 2 | Boiler steel plate; TS 490‑630 MPa, YS ≥260 MPa, comparable C‑Mn‑Si chemistry |
| China | GB 713 | Q245R (for moderate temps) | Lower tensile (400‑520 MPa) and yield (245 MPa), but similar carbon‑silicon base; may be viable for lower pressure applications |
Notes:
- Thickness-dependent element limits: For plates over 25 mm (1 in.) to 50 mm (2 in.), carbon max is 0.33 % and manganese max 1.00 %; over 50 mm to 100 mm (2–4 in.), C max 0.35, Mn max 1.10; over 100 mm, C max 0.35, Mn max 1.20. Silicon range remains 0.15–0.40.
- Impact toughness requirements are not mandatory for the base CB70 grade but can be specified by supplementary requirements (S1–S3) when low‑temperature notch toughness is needed.
- Hydrostatic test pressure is per ASTM A671 requirements and depends on design pressure, typically 60 % of the specified minimum yield strength.
- All mechanical test specimens are taken from the pipe wall or from a welded test plate produced under the same conditions. The weld seam must meet tensile and bend test requirements.
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