Document: NRC Regulatory Guide
Document ID: a4944d20-ef6e-480b-a45d-14425bedd2e5
Document Type: regulatory_guide
Title: ASME Code Cases Not Approved for Use (Rev. 8)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2219/ML22196A065.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.193
CFR Part: 
CFR Title: 

Content:
onsidered and combined with other calculated stresses to obtain the overall stress in the pipe. (g) When buried pipe is subject to large cyclic ground surface loads, such as under heavy traffic loads, fatigue shall be considered. (5) The NRC staff recognizes that Equation A-2 in Appendix A of the code case considers both pipe stiffness and soil stiffness. For soil stiffness, the DG-1408, Page 19 CODE CASE NUMBER TABLE 2 UNACCEPTABLE SECTION XI CODE CASES SUMMARY DATE OR SUPPLEMENT/ EDITION equation calls for 0.061E’. The E’ values for different soil conditions are listed in Table A-1 in Appendix A of the code case. Based on the information from “Method for Prediction of Flexible Pipe Deflection” by the Bureau of Reclamation (December 2013), each E’ value in Table A- 1 seems to be a typical or mean value (i.e., for each category of soil type and classification, about one-half of the measured deflections were higher, and about one-half were lower, than the deflection predicted using the E’ value shown). The NRC staff finds that to reduce the possibility that the actual deflection will exceed the predicted value, a design factor, Fd, shall be used to calculate soil stiffness as expressed in 0.061FdE’ where Fd, is taken from the above Bureau of Reclamation book. N-813-1 Alternative Requirements for Preservice Volumetric and Surface Examination, Section XI, Division 1 Code Case N-813 is an alternative to the provisions of the 2010 Edition of the Section XI, Paragraph IWB-3112, which does not allow the acceptance of flaws detected in the preservice examination by analytical evaluation. Code Case N-813 would allow the acceptance of these flaws through analytical evaluation. Under Section XI, Paragraph IWB-3112, any preservice flaw that exceeds the acceptance standards of Table IWB-3410-1 must be removed. Although it is recognized that operating experience has shown that large through-wall flaws and leakages have developed in previously repaired welds as a