This paper presents the results of an investigation into the frangible joint behavior of tanks designed to API 650 rules. In such tanks, the roof-to-shell joint is intended to fail in the event of overpressurization, venting the tank and containing any remaining fluid. The reasoning behind present API design formulas is reviewed. Combustion analyses, structural analyses, and the results of testing are presented. Results show that higher pressures are reached before frangible joint failure than predicted by the present API 650 calculation. One consequence is that (for empty tanks) uplift of the bottom can be expected to occur more frequently than predicted using API 650. However, uplift does not necessarily mean bottom failure. Instead, the relative strength of the shell-to-bottom and roof-to-shell joints will determine failure. This ratio is larger for larger tanks. Recommendations are made as to possible changes in the design approach of API 650.

Issue Section:
Research Papers
Topics:
American Petroleum Institute, Roofs, Storage tanks, Failure, Shells, Design, Combustion, Fluids, Structural analysis, Testing
1.
American Petroleum Institute, 1993, “API Standard 650: Welded Steel Tanks for Oil Storage,” 9th Edition, Washington, DC.
2.
Barnett, H. C., and R. R. Hibbard, 1957, “Basic Considerations in the Combustion of Hydrocarbon Fuels With Air,” Rept. 1300, Propulsion Chemistry Division, Lewis Flight Propulsion Lab., NASA, Cleveland, OH.
3.
Ferguson, C. R., 1986, Internal Combustion Engines, John Wiley and Sons, New York, NY.
4.
Lu, Zhi, and Swenson, Daniel, 1994, “User’s Manual for API-Tank: A Program for the Analysis of Storage Tanks with Frangible Roof Joints,” Manual Release 1.0, Mechanical Engineering Dept., Kansas State University, Manhattan, KS.
5.
Morgenegg, E. E., 1978, “Frangible Roof Tanks,” Proceedings, American Petroleum Institute, Refin. Dep., Midyear Meeting, 43rd, Toronto, Ontario, May 8–11, API, Vol. 57, Washington, DC, pp. 509–514.
6.
Prager, M., 1991, “Summary of Frangible Roof Failure Experiences,” provided information, Pressure Vessel Research Council, ASME, New York, NY, May 6.
7.
Swanson Analysis Systems, Inc., 1994, ANSYS Manuals, Houston, PA.
8.
Swenson, D., Fenton, D., Lu. Z., Ghori, A., and Baalman, J., 1994, “Evaluation of Design Criteria for Storage Tanks with Frangible Roof Joints,” Final Report, Kansas State University, Manhattan, KS.
9.
Yoshida, S., and Miyoshi, T., 1992, “Bifucation Buckling of the Top End Closure of Oil Storage Tanks Under Internal Pressure,” Stress Classification, Robust Methods, and Elevated Temperature Design, ASME PVP-Vol. 230.
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