API 5L X80 Pipe Calculator
ASME B31.8 — design pressure, minimum wall thickness and MAOP. SMYS is locked to the grade value.
API 5L X80 is an ultra-high-strength TMCP grade with a minimum yield of 555 MPa (80 ksi), produced to API 5L PSL2 as X80M in large-diameter LSAW. It is used for ultra-high pressure long-distance gas transmission where X70 requires excessive wall thickness.
When to use this calculator: Determine minimum wall for ultra-high pressure X80 gas transmission and verify that the thinner wall justifies the material premium over X70.
Example (API 5L X80)
| OD (mm) | Wall (mm) | Result |
|---|---|---|
| 762 | 17.5 | 18.4 MPa | 184 bar design pressure (F=0.72) |
Results are reference values — verify against API TR 5C3 (OCTG) or ASME B31.8 (line pipe) before use in final design.
Design Pressure
P = (2 × t × SMYS × F × E × T) / OD | ASME B31.8 §841.11
E = 1.0 (seamless / full-NDE ERW / LSAW), T = 1.0 (≤120 °C). Adjust per B31.8 Tables 841.115A/B for temperature derating or reduced joint efficiency.
Minimum Wall Thickness
t = (P × OD) / (2 × SMYS × F × E × T) | Rearranged ASME B31.8
Maximum Allowable Operating Pressure (MAOP)
MAOP = (2 × t_actual × SMYS × F × E × T) / OD
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