Engineering Critical Assessment — FAD Level 2A
Failure Assessment Diagram screen for a semi-elliptical axial surface crack using the BS 7910:2019 / API 579-1 (2021) Level-2A curve, Newman-Raju K, and the BS 7910 reference-stress solution. SI units (mm, MPa, MPa√m).
⚠ Safety-critical — screening ECA only. Single axial surface flaw, deepest point, fw=1, ρ=0 unless supplied. Includes an axial-flaw Folias bulging magnification and the Newman-Raju bending term (for high c²/Rt confirm K with the full BS 7910 Annex M / API 579 Part 9 cylinder solution); excludes fatigue growth, embedded/circumferential flaws, and weld mismatch. Not for safety case submission, regulatory filing, or formal engineering critical assessment without SME review — use Crackwise / API 579 software for ECA of record.
Geometry & Loading
mm
mm
MPa
MPa
MPa
Flaw & Material
mm
mm
MPa
MPa
MPa√m
—
Engineering Basis
KI = Pm·F·√(πa/Q) — Newman-Raju (1981) semi-elliptical surface crack, deepest point (φ=90°), Q = 1+1.464(a/c)1.65.
Reference stress σref = [Pb+√(Pb²+9(Pm·Mbulge)²(1−α)²)]/[3(1−α)²], α = (a/t)/(1+t/c) — BS 7910:2019 surface flaw, with the membrane stress carrying the same axial-cylinder bulging Mbulge as K (a flaw lowers the cylinder limit load → raises Lr).