1. Structural discontinuities

1.1 General

The stress concentrations that exist in a pipe, due to geometric discontinuities, are extremely high, particularly with regard to cyclic loads. It is therefore important to know where these concentrations occur and to be able to assess them.

Structural discontinuities can be classified (according to the ASME code) as :

a) extended structural discontinuity in shape or material, affecting the distribution of stress or strain through the entire wall thickness.

Example: tappings, reductions, elbows ;

b) local structural discontinuity affecting the distribution of stresses or strains in a relatively small part of the wall thickness, resulting in clearly localized stresses....