Fracture toughness curve

Table 6.2 Fracture toughness curves and indexing to account for irradiation... 

SI method Methodology Reference flaw Safety factor(s) Fracture toughness curve Comments... 

Most of the methodologies rely on a generic safety factor of 2 applied to pressure stress, with the safety factor on thermal stress set at unity. For leak and hydrostatic tests, the safety factor on pressure generally is reduced to 1.5. The Russian approach and the French Method 2 use a safety factor of unity for pressure stress, but the fracture toughness curve either has a safety factor included (Russian approach) or additional safety factors are applied to the fracture toughness curves (French Method 2). As indicated earlier, the new risk-informed approach which will appear in the 2011 edition of the ASME Code uses a safety factor of 1 on pressure stress. 

Reference fracture toughness curve and safety factors... 

Figure 12.1 presents a plot of the fracture toughness curve represented by Eq. 12.4 as a function of T-RT j for several fractional values of (j)Kic. 

---