CO₂ Pipeline Wall Thickness

Engineering Basis

• Wall thickness: ASME B31.4-2019 §403.2.1 — t = P·D / (2·S·E·F), plus corrosion allowance, divided by (1 − mill_tolerance) to obtain the nominal mill specification.
• SMYS: API 5L PSL2 line pipe — X42 (290 MPa) through X100 (690 MPa).
• Fracture arrest: Battelle / Maxey-Kiefner short form CVN = 1.26×10⁻⁴ · σ_h² · (R·t)^(1/3), with Mannucci grade correction (×1.7 for X70-X80, ×2.5 for X90+) and the DNV-RP-J202 CO₂ multiplier (×2.5) addressing the long decompression-pressure plateau.
• Arrest pressure: equals saturation pressure at the design temperature (Span-Wagner Wagner-form Psat) — for subcritical T, this is the plateau the steel must arrest above.
• Standards: ASME B31.4, DNV-RP-J202 (2017), API 5L PSL2, ISO 27913:2016, BS 7910 / ASME FFS-1.
• Limitations: Pure CO₂ assumed (no H₂S — sour service requires NACE/AMPP MR0175). For pipelines > 10 km, full BTCM analysis with measured decompression curve recommended.