American Petroleum Institute

Evaluation of Design Criteria for Storage Tanks with Frangible Roof Joints
 N PUBL 937

Annotation

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.