Reference stress solutions of flat end to cylindrical shell connection andcomparison with design stresses predicted by codes

The integrity of flat end to cylindrical shell connections (flat endcaps) o perating in the creep regime has been questioned since some failures have o ccurred in the recent past, mainly as Type IV cracking in the weldment. Fai lures in endcaps are potentially dangerous due to the fact that a crack wil l evolve from the inside and final failure will take place as 'break before leak', which in turn makes detection difficult. The codes treat the compon ent by calculating the cylinder and the flat endcap separately, whereas fai lures occur in the transition between the two in a cross-section not covere d by the codes. This paper presents reference stress solutions for endcaps derived from collapse loads using the Finite Element method. The computed r eference stress can be used for design and remaining life predictions. The reference stresses are compared to the predictions by some codes, and it is demonstrated which combinations of geometries have the potential for prema ture failure. (C) 2000 Elsevier Science Ltd. All rights reserved.