Seismic ratchet-fatigue failure of piping systems
Failures of piping systems during earthquakes have been rare. Those that have failed were either made of brittle material such as cast iron, were rigid systems between major components where component relative seismic motions tore the pipe out of the component, or were high pressure systems where a ratchet-fatigue fracture followed a local bulging of the pipe diameter. Tests to failure of an unpressurized 3-in. and a pressurized 6-in. diameter carbon steel nuclear pipe systems subjected to high level shaking have been accomplished. Failure analyses of these tests are presented and correlated to the test results. It was found that failure of the unpressurized system could be correlated well with standard ASME type fatigue analysis predictions. Moreover, the pressurized system failure occurred in significantly less load cycles than predicted by standard fatigue analysis. However, a ratchet-fatigue and ductility exhaustion analysis of the pressurized system did correlate very well. These findings indicate modifications to design analysis methods and the present ASME Code piping design rules may be appropriate to cover the ratchet-fatigue failure mode.
- Research Organization:
- Hanford Engineering Development Lab., Richland, WA (USA)
- DOE Contract Number:
- AC06-76FF02170
- OSTI ID:
- 6797377
- Report Number(s):
- HEDL-SA-3643-FP; CONF-870636-3; ON: DE87005482
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
220200 -- Nuclear Reactor Technology-- Components & Accessories
220900* -- Nuclear Reactor Technology-- Reactor Safety
ALLOYS
CARBON STEELS
CRACKS
DYNAMIC LOADS
EARTHQUAKES
FAILURES
FATIGUE
FRACTURE MECHANICS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS TESTING
MECHANICAL PROPERTIES
MECHANICAL TESTS
MECHANICAL VIBRATIONS
MECHANICS
NUCLEAR FACILITIES
NUCLEAR POWER PLANTS
PIPES
POWER PLANTS
REACTOR COMPONENTS
SEISMIC EFFECTS
SEISMIC EVENTS
STEEL-ASTM-A106
STEELS
STRAINS
TESTING
THERMAL POWER PLANTS