Classification of stresses in locally thinned tubes

Classification criteria for stresses in locally thinned regions of tubes are examined with respect to the intent of Section III of the ASME Code for Class 1 components. Depending on the size of the thinned region, the membrane stresses caused by pressure loading may be classified as general primary, primary local or secondary. The criteria for classification of membrane stresses were investigated for some simple geometry and load cases, where plastic instability is the governing mode of failure due to primary loads. (orig.)