- Author
-
Early, J. G.
|
Interrante, C. G.
- Title
- Metallurgical Investigation of a Full-Scale Insulated Rail Tank Car Filled with LPG Subjected to a Fire Environment. Failure Analysis Report. Report No. 7.
- Coporate
- National Bureau of Standards, Gaithersburg, MD
- Sponsor
- Department of Transportation, Washington, DC
- Report
-
NBSIR 75-657; Report 7
January 1975
63 p.
- Distribution
- LIMITED DISTRIBUTION Available from National Technical Information Services
- Keywords
-
tank failures; fire tests; metallurgy
- Abstract
- An analysis of the failure of an insulated rail tank car, RAX 202, which had been tested to failure in a fire enivronment at White Sands Missile Range, New Mexico, was requested by the Federal Railroad Administration, Department of Transportation. The tank car, filled with liquified petroleum gas (LPG), failed after aproximately 94 minutes of exposure to a JP-4 jet fuel fire. Five plate samples were selected for laboratory study at the National Bureau of Standards. The results of metallurgical investigations suggest that a region approximately 30 inches in length near the top of the tank car in shell course 3 was the site of the initial rupture of the tank car. The results of stress-relieving experiments conducted on samples taken from the top and bottom of the car indicated that the top of the tank car experienced temperatures of 1200 deg. F to 1250 deg. F for times of between 10 to 15 minutes. The fracture features of the initial rupture were indicative of failure by a stress-rupture mechanism. It was concluded that this 30-inch stress-rupture crack led to tensile overload, instability and to the onset of rapid crack propagation in a shear mode, with the initial shear fracture propagating as an extension of the original stress-rupture crack. Within a short distance, this shear fracture turned 90 deg. and propagated in the plate rolling direction, a result explained by the anisotropy of the fracture resistance of this steel at the elevated temperatures of the test.