Experimental and analytical assessment of circumferentially surface-cracked pipes under bending
This study was performed to assess the validity of various techniques to predict maximum loads for circumferentially surface-cracked pipes under bending. Experimental data were developed for both carbon steel and stainless steel pipes. Predictions of maximum loads were made using the net-section-collapse method, the IWB-3640 analysis procedures, and a newly developed finite-length surface-cracked pipe J-estimation method. The net-section-collapse method gave good maximum-load predictions for certain types of pipe. However, for pipes with large radius to thickness (R/sub m//t) ratios and/or low toughness this analysis method tended to overpredict the experimental maximum load. A plastic-zone screening criterion was developed to show when this method was valid and when elastic-plastic fracture mechanics should be used. The limit-load procedures embodied in IWB-3640 provide the desired underprediction of the failure stress. The average failure stress for the nine stainless steel base metal experiments was 61% higher than predicted by Table IWB-3641-1 and 23% higher than predicted by the Source Equations. For the three stainless steel flux weld experiments the predicted failure stresses were adjusted by a stress multiplier to account for the lower toughness of the flux welds. The average failure stress for the flux weld experiments was 78% higher than predicted by Table IWB-3641-5 and 39% higher than predicted by the Source Equations. Predictions from two versions of the new finite-length surface-cracked pipe J-estimation method were compared to experimental results. One version is for pipes with large R/sub m//t ratios (SC.TNP) while the other is a more general approach (SC.TKP) where the large R/sub m//t ratio restriction is relaxed. The results show that the SC.TNP method tends to overestimate the maximum loads by 15% on the average whereas the SC.TKP method tends to underpredict the maximum loads, as desired, by 32%.
- Research Organization:
- Battelle Columbus Div., OH (USA); Nuclear Regulatory Commission, Washington, DC (USA). Div. of Engineering Safety
- OSTI ID:
- 6556560
- Report Number(s):
- NUREG/CR-4872; BMI-2149; ON: TI87900678
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
CARBON STEELS
PIPES
CRACKS
PREDICTION EQUATIONS
FRACTURE MECHANICS
STAINLESS STEELS
BENDING
FAILURES
STRESSES
TESTING
ALLOYS
CHROMIUM ALLOYS
CORROSION RESISTANT ALLOYS
EQUATIONS
IRON ALLOYS
IRON BASE ALLOYS
MECHANICS
STEELS
220200* - Nuclear Reactor Technology- Components & Accessories
360103 - Metals & Alloys- Mechanical Properties