Crack Growth Prediction for Cracked Dissimilar Metal Weld Joint in Pipe Under Large Seismic Cyclic Loading

2018 ◽  
Author(s):  
Yoshihito Yamaguchi ◽  
Jinya Katsuyama ◽  
Yinsheng Li
Keyword(s):  
Risk Assessment ◽  
Crack Growth ◽  
Seismic Risk ◽  
Evaluation Method ◽  
Seismic Loading ◽  
Steel Pipes ◽  
Dissimilar Metal ◽  
Growth Evaluation ◽  
Nickel Based Alloy ◽  
Metal Weld

Seismic risk assessment of nuclear power plants (NPPs) based on seismic hazard and fragility analyses of structures/components has become important since Japanese NPPs have experienced several large earthquakes beyond the design basis ground motion. In addition, cracks resulting from the long-term operation of NPPs have been detected in piping system of NPPs. For example, in the pressurized water reactor environment, crack initiation and propagation due to primary water stress corrosion cracking (PWSCC) have been observed in dissimilar metal welds made of nickel-based alloy. Therefore, fragility analyses related to seismic probabilistic risk assessment considering such PWSCC and seismic loading are important for more realistic seismic risk assessment. In our previous study, a fragility analysis method for cracked pipes that is applicable for the carbon and stainless steel pipes has been developed. The developed method consists of two functions for evaluating the crack growth due to seismic loading as well as the age-related degradation. Since the crack growth evaluation method is available for only carbon steel and stainless steel pipes, it is important to enhance the applicability of the method to dissimilar metal welds of pipes where the cracks due to PWSCC were observed. In this study, an extensive study for crack growth evaluation method is performed for the dissimilar metal welds. Here, applicability of the previously developed method to a nickel-based alloy weld is investigated. We performed crack growth tests using the center cracked plate specimens and welded pipe specimens with circumferential through-wall crack machined from dissimilar metal weld joint of pipes. It is found that the amount of crack growth predicted by our crack growth evaluation method are in good agreement with the experimental results. Therefore, we conclude that the previously developed method can be widely used for evaluating the crack growth behavior under seismic loading conditions in the nuclear piping including dissimilar metal welds of pipes.

Crack Growth Evaluation for Cracked Carbon and Stainless Steel Pipes Under Large Seismic Cyclic Loading

2015 ◽  
Author(s):  
Yoshihito Yamaguchi ◽  
Jinya Katsuyama ◽  
Yinsheng Li ◽  
Kunio Onizawa
Keyword(s):  
Crack Growth ◽  
Nuclear Power ◽  
Power Plants ◽  
Evaluation Method ◽  
Cyclic Response ◽  
Term Operation ◽  
Steel Pipes ◽  
Wave Forms ◽  
Growth Evaluation ◽  
Large Earthquakes

Japanese nuclear power plants have recently experienced several large earthquakes beyond the previous design basis ground motion. In addition, cracks resulting from long-term operation have been detected in piping lines. Therefore, it is very important to establish a crack growth evaluation method for cracked pipes that are subjected to large seismic cyclic response loading. In our previous study, we proposed an evaluation method for crack growth during large earthquakes through experimental study using small specimens. In the present study, crack growth tests were conducted on pipes with a circumferential through-wall crack, considering large seismic cyclic response loading with complex wave forms. The predicted crack growth values are in good agreement with the experimental results for both stainless and carbon steel pipe specimens and the applicability of the proposed method was confirmed.

OS0810 The proposal of crack growth evaluation method for piping under seismic loading

2012 ◽  
Vol 2012 (0) ◽  
pp. _OS0810-1_-_OS0810-3_
Author(s):  
Yoshihito YAMAGUCHI ◽  
Yinsheng LI ◽  
Jinya KATSUYAMA ◽  
Kunio ONIZAWA
Keyword(s):  
Crack Growth ◽  
Evaluation Method ◽  
Seismic Loading ◽  
Growth Evaluation

scholarly journals The Proposal of Crack Growth Evaluation Method for Piping under Seismic Loading

2013 ◽  
Vol 79 (802) ◽  
pp. 730-734
Author(s):  
Yoshihito YAMAGUCHI ◽  
Yinsheng LI ◽  
Jinya KATSUYAMA ◽  
Kunio ONIZAWA
Keyword(s):  
Crack Growth ◽  
Evaluation Method ◽  
Seismic Loading ◽  
Growth Evaluation

OS1427 Evaluation method of crack growth in reactor piping subjected to seismic loading beyond small scale yielding condition

2013 ◽  
Vol 2013 (0) ◽  
pp. _OS1427-1_-_OS1427-3_
Author(s):  
Yoshihito YAMAGUCHI ◽  
Makoto UDAGAWA ◽  
Yinsheng LI ◽  
Jinya KATSUYAMA ◽  
Kunio ONIZAWA
Keyword(s):  
Crack Growth ◽  
Evaluation Method ◽  
Seismic Loading ◽  
Small Scale ◽  
Small Scale Yielding ◽  
Yielding Condition ◽  
Scale Yielding

OS0807 Evaluation of crack growth under seismic loading in nickel based alloy weld

2014 ◽  
Vol 2014 (0) ◽  
pp. _OS0807-1_-_OS0807-3_
Author(s):  
Yoshihito YAMAGUCHI ◽  
Jinya KATSUYAMA ◽  
Yinsheng LI ◽  
Yutaka Nishiyama ◽  
Kunio ONIZAWA ◽  
...  
Keyword(s):  
Crack Growth ◽  
Seismic Loading ◽  
Nickel Based Alloy ◽  
Alloy Weld

Validation of Welding Residual Stress Model Using Results From a Pressurizer Surge Nozzle Mockup

2011 ◽  
Author(s):  
Doug Killian
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Crack Growth ◽  
Material Properties ◽  
Welding Residual Stress ◽  
Stress Model ◽  
Dissimilar Metal ◽  
Dissimilar Metal Weld ◽  
Metal Weld

Although numerical welding simulation is now commonly used in the nuclear industry to predict residual stresses in reactor vessels and associated piping components, there are currently no universally accepted guidelines for performing such analysis. Moreover, due to the complexity of the calculations and varying analytical procedures among analysts, there remains a need to validate predictions of residual stress against benchmark studies. As part of an industry initiative to manage the degradation of dissimilar metal welds in pressurized water reactor piping that are susceptible to primary water stress corrosion cracking, the U.S Nuclear Regulatory Commission embarked on a multi-phased program to validate welding residual stress models. The aim of Phase II of this program is to obtain measured residual stresses from a pressurizer surge nozzle dissimilar metal weld mockup for use in comparisons with numerically predicted stresses. This paper presents results of finite element analysis for various stages during the fabrication of a 14–inch pressurizer surge nozzle mockup, including an Alloy 82 dissimilar metal weld between a stainless steel safe end and carbon steel nozzle, an inside surface weld repair (back weld) and fill-in weld (weld build-up), and a stainless steel “field” weld attaching a section of straight pipe to the safe end. The NRC validation program was structured to allow participants to first calculate results using their own material properties, and then tune their welding simulations to thermocouple data. This was followed by reanalysis using NRC-supplied material properties. The program was conducted as a round robin analysis among an international group of participants and formatted as a blind validation project wherein results were submitted to the NRC prior to receipt of thermocouple and material property data. Results were obtained for both kinematic and isotropic hardening rules to study the effect of these two extreme measures of material characterization on the development of residual stress. Predicted stresses are then compared to measured stress data obtained by the deep-hole drilling technique at multiple locations through the thickness of the weld. The NRC residual stress model validation project serves as a valuable contribution to the understanding of how residual stresses are developed in dissimilar metal welds. The correlation of calculated residual stresses with measured data from a relevant mockup also serves to increase confidence in predicting crack growth in these primary pressure boundary welds by removing much of the uncertainty previously associated with residual stress input to crack growth analysis.

SCC Crack Growth Analysis for a Dissimilar Metal Weld Using Advanced FEA

2018 ◽  
Author(s):  
Takuya Ogawa ◽  
Masao Itatani ◽  
Takahiro Hayashi ◽  
Toshiyuki Saito
Keyword(s):  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Weld Joint ◽  
Growth Analysis ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Dissimilar Metal ◽  
Growth Properties ◽  
Dissimilar Metal Weld ◽  
Metal Weld

Management of plant service life is a key issue for improving the safety of light water reactors. Some incidents of primary water stress corrosion cracking (PWSCC) of pressurized water reactor (PWR) components, such as a primary loop piping/nozzle weld, and intergranular stress corrosion cracking (IGSCC) of boiling water reactor (BWR) components, such as a shroud support weld, have been reported in the past. When a crack is detected, crack growth analysis is required as part of the structural integrity assessment of the component with the crack. In Japan, the “Rules on Fitness-for-Service for Nuclear Power Plants” of the Japan Society of Mechanical Engineers (JSME FFS Code) describes the conventional methodology for analyzing crack growth. The methodology assumes a semi-elliptical crack shape and is based on crack growth calculation at only the deepest and surface points of the crack. However, the actual crack growth behavior is likely to be very different from that analyzed by the conventional methodology due to the complex distribution of residual stress and dependency of crack growth properties on the materials composing the weld joint, particularly in the case of cracks in a dissimilar metal weld. Recently, crack growth analysis techniques using finite element analysis (FEA) have been used to analyze crack growth behavior in more detail. In this study, a program code was developed for SCC crack growth analysis that consists of fracture mechanics analysis by “ABAQUS”, crack growth calculation and automatic remesh of the FE model by in-house code. Case studies of SCC crack growth analysis for a dissimilar metal weld were performed and the analysis results were compared with those obtained by the conventional methodology. As a result, it was confirmed that the conventional methodology provides a conservative estimation of crack growth behavior. It was also found that the difference in crack growth properties of individual materials composing the weld joint had a significant effect on the crack growth behavior, particularly on a dissimilar metal weld. Furthermore, the effect of the material anisotropy of the SCC crack growth rate for the weld metal on the crack growth behavior was investigated.

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