RBI for Atmospheric Storage Tanks

Two API projects are co-sponsoring an effort to develop a risk based inspection (RBI) method for atmospheric storage tanks (AST). One of the projects is the long standing RBI project that is developing RBI methods for all types of pressure equipment; and the other is the more recently formed group that is focused on developing risk assessment methods for oil and gasoline terminals and other storage tank facilities. This article covers the preliminary model that has been proposed for both projects by the joint contractor for both projects, DNV. As such, this model is a draft and still undergoing review and revision by the two API project groups.

API 653, In-service Tank Inspection Standard, now recognizes the value of RBI for storage tanks for determining tank inspection strategies, including setting of inspection intervals. But it states specifically that the method must be conducted by qualified RBI practitioners, and the assessments must be approved by API authorized tank inspectors and qualified engineers. These assessments must be reviewed for potential changes in risk, at least every 10 years, or more often, as changes occur.