Session: CS-08-02 ASME Code Section XI Activities-2

Paper Number: 125234

125234 - Small A/l Ratios and the Use of Asme Section Xi Appendix a Stress Intensity Factor Coefficients for Circumferential Id Surface Flaws in Cylinders 

In the 2023 Edition of ASME Section XI Article A-3000, closed form equations are included to calculate stress intensity factors (K_I) for circumferential and axial flaws on the inside and outside surfaces of cylinders.  The stress intensity factors (K_I) are based on non-dimensional coefficients (G_i) that allow for the calculation of stress intensity factors (K_I) for a fourth order stress field. The closed form equations are based on tabular data from API-579.  The tabular data covers a/l ratios of 1/2 to 1/64 depending on the Ri/t ratio.  For some small a/l ratios there could be flaws whose a/l ratio is beyond the a/l ratio covered by API-579.

This paper addresses issues that have been raised on how the closed form equations for circumferential flaws are extended to small a/l ratios when no data was available for the original curve fit.  Due to the available data from API-579, the only geometry with the issue is the circumferential flaw, not the axial.  Additional finite element modeling shows that the closed form equations provide a good representation of the G_i coefficients for small a/l ratios for the ID flaw. This paper does not address the OD circumferential flaw.

Presenting Author: Darrell Lee BWX Technologies

Presenting Author Biography: For the last 40 years, Darrell has been involved in analytical and experimental stress analysis with the Babcock & Wilcox Company and BWX Technologies. During the last 10 years, he has focused on pressure vessel design and fabrication. He is active in ASME Codes and Standards and is a member of the Working Group Flaw Evaluation, Subgroup Evaluation Standards and Section XI Standards Committee.

Authors:

Darrell Lee BWX Technologies
Sureshkumar Kalyanam Westinghouse
Steven Xu Kinectrics, Inc.