Defects　significantly　affect　the　carrying　capacity　of　pipe　elbows.　Accurately　estimating　the　capacity　permits　fewer　pipe　inspections　and　replacements,　saving　time　and　reducing　costs.　To　study　the　effect　of　defects,　a　90　pipe　elbow　model　with　a　1016　mm-diameter　and　19.9　mm　wall　thickness　was　built.　The　material　is　API　X80　steel　and　the　curvature　radius　is　6D.　The　plastic　failure　criterion　and　twice　elastic　slope　method　were　adopted　to　determine　the　limit　internal　pressure　load.　Using　the　commercial　finite　element　software,　Abaqus,　the　influences　of　defect　location,　defect　depth,　defect　length,　defect　width　and　pipe　wall　thickness　on　the　ultimate　bearing　capacity　of　an　pipe　elbow　with　ellipsoidal　pits　was　studied.　Through　multiple　nonlinear　regression　analysis　and　nonlinear　fitting,　formulas　for　calculating　the　ultimate　internal　pressure　load　of　large-diameter　elbows　with　defects　under　various　influencing　factors　were　obtained.　The　formulas　can　provide　guidance　and　reference　for　evaluating　the　residual　strength　of　large-diameter　elbows　with　defects.　©　2020　Elsevier　Ltd