ThinkTank

FFS and RBI for Tanks

Equity Engineering has led the way in applying FFS and RBI technologies to Aboveground Storage Tanks (ASTs), including developing an AST module for API RBI software that considers risk scenarios for tank shell and floor components.

We are also leaders in the development and use of Finite Element Analyses to evaluate AST settlement. Joel Andreani, our specialist in tankage, has co-authored several papers including "An Evaluation of Procedures for Determining the Fitness for Service of Settled Aboveground Storage Tanks," (Andreani, Osage, others), "Final Report on the Study of Out - of - Plane Settlement," (Andreani, others), and "Non-Linear Finite Element Analysis of Edge Settlement in Riveted Aboveground Storage Tanks," (Andreani). These papers are cited as references for many of the current revisions to Appendix B of API RP 653, Tank Inspection, Repair, Alteration, and Reconstruction.

The ThinkTank Program

Integrated FFS and RBI capabilities
Specialized tank settlement evaluations
Hydrotest exemption analyses
API RBI for tanks
Remaining Life assessments
Rerating using procedures in API 653, API 579, and other industry standards
Evaluation of fire damage
Aboveground Storage Tank FFS Tool Set
Specialized Assessments of Refrigerated & Liquefied Hydrocarbon Gas Tanks

Case Studies

Equity has performed numerous tank assessments that have saved millions in unnecessary repairs and business interruption. Some examples:

An evaluation of Stress Corrosion Cracking in ammonia storage tanks and spheres: By conducting in-depth RBI and FFS assessments, we developed inspection plans that emphasized non-intrusive inspection techniques and focused inspection where it was needed the most to manage risk
API 579 Level 3 assessment of nearly through-wall localized pitting in a sludge tank: We determined the tank did not require immediate repairs, and developed criteria for pit size, pit depth and spacing at which repair should be considered
Hydrostatic Test Exemption assessment of a doorsheet repair to a gasoline tank: We performed Finite Element Analyses of the tank and developed inspection criteria based on API 579 flaw assessment procedures that allowed the tank to be exempted from hydrotest
Fitness-For-Service assessment of severe tank bottom settlement resulting in snap-through buckling of the cone-up bottom: We performed Finite Element Analysis of the tank's post-buckling behavior and determined the permissible time to next inspection based on settlement rates. We also developed criteria for the evaluation of replacement of roof support members warped and buckled by the settlement
Finite Element Analysis of a sagging external floating roof: We determined the roof's drainage system was inadequate for the rainfall intensity at the site and the pontoon-to-deck geometry. We re-designed the roof's drainage system and detailed pontoon-to-deck stiffening measures to avoid future pontoon-to-deck failure or roof instability
Re-design of a tank with failed welds at an internal partition plate: We performed Finite Element Analyses of a frequently filled tank that had a full shell height internal partition used to segregate two products in the tank. We re-designed the partition to reduce the fatigue stress range to a permissible limit

Featured Expert

Joel Andreani
P.E.

Mr. Andreani performs Fitness-For-Service evaluations, engineering specification and design support, engineering training, and project consulting...

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Joel Andreani, P.E.

Joel Andreani Mr. Andreani performs Fitness-For-Service evaluations, engineering specification and design support, engineering training, and project consulting on a wide variety of refinery and chemical plant equipment. A pressure-containment and structural specialist, Mr. Andreani has worked in various refinery technical service groups providing engineering support to refineries and chemical plants worldwide.

Mr. Andreani has developed advanced skills in Finite Element Analyses with emphasis on non-linear behavior. He performs advanced stress analysis in the design and assessment of tankage and spheres, piping, pressure vessels, steel and concrete structures, and foundations. He appraises the service suitability of existing equipment in accordance with API 579. He is also an expert in tank settlement, having been one of the primary developers of API 653 edge settlement procedures, and the leader of a current API project to re-write API 653 rules on differential shell and global bottom settlement. He analyzes vibration of equipment and structures, and performs fatigue assessments, structural reliability evaluations and risk assessments.

Mr. Andreani has managed company specification programs and has developed over 50 design, fabrication, inspection and testing specifications for tankage, piping and structures, and specifications for wind, seismic and blast load criteria for petrochemical equipment and structures for petrochemical facilities worldwide. He performs design reviews for tankage, piping, pressure vessels, structures and foundations as part of major refinery capital projects, including expansions, revamps and de-bottlenecking projects. In addition, Mr. Andreani serves on the API Aboveground Storage Tank Subcommittee on Design, and performs code compliance calculations and interpretations for tankage, piping, pressure vessels, structures and foundations.