In recent years, the demand for the reliable and economically justifiable assessment techniques for integrity of large scale above-ground oil storage thanks, as ones of the aging infrastructures, is increasing.Under this situation of Japan, the HPI (the High Pressure Institute of Japan) made the adhoc committees, which have been sponsored by the Japan National Oil Corporation (石油公司)， working on the necessary technologies to assess the integrity and to provide the rational maintenance for the national crude oil storage tanks exceeding a capacity of 100,000kl. The committees addressed mainly on the problems of underside corrosion of the bottom floors, on the durability evaluation technique of internal protective- coating systems, and also on fracture mechanical assessment method for crack growth behavior at the toe of shell- annular fillet welds when, especially, the tank undergoes a strong earthquake, with along reliable through-coating NDT techniques for cracks in the welds. Some of the results in the committee works for six years since 1991 are presented in this issue.This article surveys the present situation of above-ground tank management and integrity evaluation technologies in Japan. It also focuses on some problems posed and identified from the adhoc committee works, which are on the underside corrosion of tank floors, on the internal coating and linings used as the corrosion protection and on the defect assessment method for cracks in fillet welds, including the through-coating NDT techniques for harmful cracks to structural soundness in above- ground oil tanks.
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