API PUBL 937 : 1996

Description / Abstract:

API PUBL 937, 1996 Edition, April 1996 - Evaluation of Design Criteria for Storage Tanks with Frangible Roof Joints

FOREWORD

American Petroleum Institute (API) provides standards for the design, construction and inspection of storage tanks. One of the family of design standards, API 650--Welded Steel Tanks for Oil Storage--is the target of the research addressed by this Bulletin. API 650 includes, among other important design provisions, criteria governing the design of frangible roof joints for welded steel, above-ground, cylindrical, storage tanks.

The frangible joint is the primary design feature which assures the functional integrity of the cylindrical shell and bottom joint to contain the liquid in the event of an unexpected over-pressurization of a tank. Because of the importance of the frangible joint design feature from a safety and environmental implication, API decided additional research was warranted. In May 1989, Guido Karcher, acting in behalf of API, defined specific areas where research is needed to evaluate the frangible roof joint provisions of API 650 standard and initiated a request to PVRC Design Division to address these research needs. The request was assigned to the Committee on Dynamic Analysis and Testing for administrative and technical direction. The main goals of the Committee included initiating the research program, monitoring the progress, assuring the results are responsive to the API request and making sure that the results are clearly and concisely documented. Liaison with the Committee on Shells and Ligaments was maintained throughout the research activities.

The Committee on Dynamic Analysis and Testing solicited proposals from qualified organizations to address the needs defined in Guido Karcher's May 1989 letter. The solicitation resulted in four proposals which were thoroughly and objectively evaluated by the Committee. The proposal by Kansas State University, Professors Daniel Swenson and Don Fenton, was selected as the most responsive to the defined needs. A PVRC grant (91-02) was issued in October 1990 for the first phase of the three-phase research program.

Thanks to Dr. Martin Prager for his technical and administrative skills and the dedication and aggressive nature of the research team at Kansas State University under the direction of Professor Swenson, the comprehensive three-phase research program, including a final report of the analytical and experimental evaluations, an interactive Windows based PC program for the analysis of storage tanks with frangible roof joints and user manual for the PC program was completed on schedule in April 1994--duration of approximately 3½ years from the time the grant was issued. The thoroughness and quality of the products are commendable.

The research team at Kansas State University which consisted of:

• co-investigators Professors Daniel Swenson and Don Fenton

• graduate research assistants Zhi Lu, Asif Ghori and Joe Baalman

• an undergraduate honor student Mark Devries deserves commendable recognition for a job well done.

In addition special thanks are extended to:

• Mr. Richard Basile for his invaluable liaison efforts with the responsible API Committees, feedback to PVRC and project directors, and review of research reports and the PC-based computer program

• Dr. Greg Hollinger for his liaison efforts with the Committee on Shells and Ligaments

• Mr. J. C. Thompson, a veteran expert in the field, for his valuable comments from an independent consultant's viewpoint.

The members of the Committee on Dynamic Analysis also provided significant contributions by direct interaction with the project directors during numerous progress reports provided at regular Committee meetings and the review of draft reports for each phase of the research.

Although specific acknowledgements to others that assisted in the research are given in Section 9.0 of this Bulletin, it is appropriate to note the cost support provided by Texaco, E1 Dorado Plant in constructing the tanks utilizing Ace Construction.

The project was jointly funded by PVRC and API with the majority of the funds provided by API. PVRC thanks API for the support of this extremely important project which not only provides an analytical and experimental bases for the current API 650 design rules for frangible roof joints, but also provides the technical bases for potential improvements to the current rules.