Document: NUREG-0800
Document ID: d5452e7b-1e61-498b-9e3d-71073b3328ef
Document Type: srp
Title: LEAK-BEFORE-BREAK EVALUATION PROCEDURES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0302/ML030280295.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.6.3
CFR Part: 
CFR Title: 

Content:
stress used to construct the master curve is (a = + () 05 y u when the yield strength, oy , and the ultimate strength, cru' at temperature are known. If the yield and ultimate strengths at temperature are not known, then Code minimum values at temperature can be used, or alter natively if (Sl) r 2.5, then 17M rf = 51 ksi, or if (S1i >2.5, then 17M Gf = 45 ksi, The value of SI used to enter the master curve for base metal and TIG welds is SI = M (Pm + Pb) (7) where Pb = the combined primary bending stress, including deadweight and seismic components. Shielded Metal Arc (SMAW) and Submerged Arc (SAW) Welds: The flow stress used to construct the master curve must be 51 ksi. 3.6.3-8 The value of SI used to enter the master curve for SMAW and SAW is =1 = M (Pm + Pb + Pe) Z (8) where Pe = combined expansion stress at normal operation, Z = 1.15 [1.0 + 0.013 (OD-4)] for SMAW, (9) Z = 1.30 [1.0 + 0.010 (OD-4)] for SAW, (10) and OD = pipe outer diameter in inches. When the allowable flaw length is determined from the master curve at the appropriate SI value, it can be used to determine if the required margins on load and flaw size are met using the following procedure: For an absolute sum load combination method, M = 1.0, and if the allowable flaw length from the master curve is equal to at least twice the leakage size flaw, then the margins on load and flaw size are met. For the algebraic sum method of load combination, first let M = 1.4, and if the allowable flaw length from the master curve is at least equal to the leakage size flaw, then the margin on load is met. Second, let M = 1.0 and if the allowable flaw length from the master curve is at least twice the leakage size flaw, then the margin on flaw size is met. Additional guidance on the fracture mechanics evaluation can be found in NUREG-1061, Volume 3, Chapter 5, dated November 1984, and entitled "Report of the U.S. Nuclear Regulatory Commission Piping Review Committee" and subtitled "Evaluation of Potential for Pipe