Assessment of plastic loads of critical throughwall circumferentially cracked pipe bends with structural distortions under in-plane bending

• Plastic loads were evaluated in the analysis of cracked 90° pipe bends.
• Effects of structural distortions were quantified and compared.
• Assessment of collapse moments is preferred over evaluation of limit moments.
• Ovality has pronounced effect on limit loads for cracked pipe bends considered.

A comparative evaluation of limit moments based on small displacement and collapse moments based on large displacement for structurally distorted throughwall circumferentially cracked pipe bends, under in-plane closing bending were carried out using finite element analysis. The moments were obtained employing the twice-elastic-slope method. Results indicate the influence of thinning is minimal whereas the effects of ovality on both limit and collapse moments for the cases considered are significant and therefore thinning need not be considered in the analysis. Moreover determination of collapse moments is preferred when ovality is incorporated in the analysis of pipe bends with the geometries considered.