For accurate assessment of residual life of components of Type 304L(N) material, studies are needed to be carried out in water environment simulating the normal operating conditions of typical boiling water reactor excluding irradiation effects. They observed higher FCGR under low flow conditions, between temperature range from 150 ☌ to 320 ☌ subjected to moderate loading frequency regime. in another study, showed the effect of flow rate and temperature on FCGR of Type 304L stainless steel. The effect of loading frequency, load ratio (R, the ratio of minimum load to maximum load in a cycle), rise time were also brought out in their test studies. observed higher FCGR in the temperature range of 150–300 ☌. , have carried out extensive investigations on austenitic stainless steel in Pressurized Water Reactor (PWR) primary coolant environment. The FCGR curve for austenitic stainless steel in water environment is not available in ASME section XI. Assessment of residual life without considering synergistic effects of corrosion and fatigue may lead to un-conservative prediction of life. Synergistic effect of corrosion and fatigue loading would increase the crack growth rate significantly. Subsequently, initiated crack will grow locally due to fatigue (cyclic loading) and corrosion in water environment. Water environment effect on fatigue crack initiation was studied extensively using smooth specimens and is being used in design analyses,. In past, the transferability of FCGR parameters from lower length scale of C(T) specimen to full scale piping component has been studied in detail, for assessment of the residual life. The FCGR curves are determined from standard pre-cracked specimens such as Compact Tension (C(T)) and Three Point Bend (TPB). In order to demonstrate the Leak-Before-Break (LBB) design criterion and predict the residual life of piping component with flaw, the FCGR curves are required. This is attributed to the presence of flaws which have either gone undetected during pre-service inspection or appeared in due course of its service. These failures can occur even though the operating stresses are well below the allowable stress limits. Failures in piping components can occur due to fatigue cycling.
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