Session: CS-07-04 The Warren H. Bamford Memorial Symposium on Recent Developments in ASME Codes and Standards-4

Paper Number: 155989

155989 - High Temperature Flaw Evaluation Code Case N-934: Effect of Transients 

Abstract: 

The Working Group on High Temperature Flaw Evaluation (HTFE), which originally reported to both Section XI and Section III Division 5 but now is being assigned to Section XI Division 1, has developed a code case to address high temperature flaw evaluation (Code Case N-934).  The code case integrates the creep rupture rules of Section III Division 5 and the fracture rules in Section XI which are enhanced to address high temperature crack growth. 

The purpose of this procedure is to evaluate the growth of a single, characterized flaw for a defined evaluation period in a metallic component where the future thermomechanical loads are known or approximated.  The procedure was originally developed to assess the growth of the flaw under periods of constant primary load.  Code Case N-934 is currently being improved to include transient and secondary (thermal type loads).  Crack growth is accumulated over a series of time incrementsand creep rupture and crack instability are assessed.  The method is based on the R5 code. 

Paper PVP2022-85957 provided examples of use of the Code Case to provide HTFE assessments of several primary loaded crack growth problems.  In this paper, several examples of the use of the code case to assess HTFE transients based on the developing enhancements of Code Case N-934 are provided.  The example problems considered include an external surface cracked pipe subjected to internal pressure and a circumferential cracked pipe subjected to various combinations of internal pressure and bending loads using a complicated creep constitutive law for 316L stainless steel.  The enhanced Code Case N-934 procedures are used to estimate the transient effects of creep crack growth and include the estimates of the C(t) integral for HTFE crack growth assessment.  Comparisons of the estimates of C(t) with finite element solutions show that the Code Case procedures provide conservative estimates.  Crack evolution using the conservative crack growth law in Code Case N-934 is compared to results using a more accurate creep crack growth law based on material test data.  The implications on high temperature crack growth life are discussed.

Presenting Author: Frederick (bud) Brust Engineering Mechanics Corporation of Columbus

Presenting Author Biography: F. W. Brust works at Engineering Mechanics Corporation.

Authors:

Frederick (bud) Brust Engineering Mechanics Corporation of Columbus
Cedric Sallaberry Engineering Mechanics Corporation
Mark Messner Argonne National Laboratory
Mark Petkov Kairos Power