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
220200* -- Nuclear Reactor Technology-- Components & Accessories
36 MATERIALS SCIENCE
360103 -- Metals & Alloys-- Mechanical Properties
ALLOYS
BENDING
CARBON STEELS
CHROMIUM ALLOYS
CORROSION RESISTANT ALLOYS
CRACKS
EQUATIONS
FAILURES
FRACTURE MECHANICS
IRON ALLOYS
IRON BASE ALLOYS
MECHANICS
PIPES
PREDICTION EQUATIONS
STAINLESS STEELS
STEELS
STRESSES
TESTING