A nonlinear analysis procedure is validated in this paper to predict deformation response, up to collapse, of thin-walled Liquid Metal Reactor (LMR) piping elbows. Nonlinear shell analysis predictions are compared with experimental measurements of two full-scale large diameter (406 mm), thin-walled (D/t = 38), piping elbows tested at room temperature and at an elevated temperature in the Multi-Load Test Facility (MLTF) at Westinghouse. The overall and local deformation predictions agree very well with the measured deformation responses up to 60 percent of the measured plastic collapse moment, Mpce. The analytical-experimental correlation is reasonable up to 0.8 Mpce. At higher load levels the correlation is not as good; at collapse the analysis overpredicts measured deformations by as much as 30 percent.