Control of corrosion-fatigue in NGV fuel cylinders. Topical report, January 1987-August 1989
Natural gas vehicle (NGV) fuel cylinders are periodically recertified using hydrostatic testing. However, the procedure is costly, and of questionable value for the detection of corrosion-fatigue cracking, the most serious form of cylinder degradation. The present program examines the feasibility of an improved recertification procedure based on in-service acoustic emissions (AE) monitoring of cracks during cylinder refueling, combined with fracture mechanics testing and analysis to determine the optimum inspection period, the level of detectability required, and the cylinder retirement criteria. Laboratory experiments were used to measure the corrosion-fatigue and fracture resistance of several cylinder steels, as well as to provide basic information on AE sources. A comparison of the latter information with the background noise obtained during cylinder refueling was used to demonstrate the feasibility of the AE procedure. An analytical fracture mechanics model for corrosion-fatigue crack growth in the cylinders was also developed and used, together with the measured materials' properties, to predict cylinder life as a function of crack size, operating pressure, and environment. Conditions for leak-before-break of the cylinder were also examined. Areas requiring additional work are defined, including the important task of determining the minimum AE-detectable crack size in actual cylinders.
- Research Organization:
- Southwest Research Inst., San Antonio, TX (United States)
- OSTI ID:
- 5483420
- Report Number(s):
- PB-91-178749/XAB; CNN: GRI-5086-252-1440
- Country of Publication:
- United States
- Language:
- English
Similar Records
Fracture mechanics analysis of NGV fuel cylinders. Part 1. Steel cylinders. Topical report, August 1989-February 1993. [NGV (Natural Gas Vehicles)]
Fracture mechanics analysis of NGV fuel cylinders. Part 2. Metal cylinder liners. Topical report
Related Subjects
034000 -- Natural Gas-- Combustion
36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
42 ENGINEERING
420500* -- Engineering-- Materials Testing
ACOUSTIC EMISSION TESTING
ACOUSTIC TESTING
ALLOYS
CERTIFICATION
CHEMICAL REACTIONS
COMBUSTION
CONTAINERS
CORROSION FATIGUE
CRACK PROPAGATION
CRACKS
ENERGY SOURCES
FATIGUE
FEASIBILITY STUDIES
FLUIDS
FOSSIL FUELS
FRACTURE MECHANICS
FUEL GAS
FUEL SYSTEMS
FUELS
GAS CYLINDERS
GAS FUELS
GASES
IN-SERVICE INSPECTION
INSPECTION
IRON ALLOYS
IRON BASE ALLOYS
LEAK DETECTORS
LEAKS
LOADING
MATERIALS HANDLING
MATERIALS TESTING
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MECHANICS
NATURAL GAS
NONDESTRUCTIVE TESTING
OXIDATION
PRESSURE DEPENDENCE
SERVICE LIFE
SIZE
STEELS
TESTING
THERMOCHEMICAL PROCESSES
VEHICLES