Vista Precision Solutions, Inc.

Douglas W Mann

Joseph W Maresca, Jr

Stephen D Ford

A method and apparatuses to extend the time interval between out-of-service, in-tank inspections while insuring structural integrity using a risk-based, Bayesian statistical approach comprised of a passing leak detection test, determining that the tank is not leaking, estimating a thickness of the tank floor to estimate a corrosion rate, and conducting a risk assessment using the result of the leak detection test, the corrosion rate and thickness of the tank floor, and statistical data of tank failures.

Method for extending the time between out-of-service, in-tank inspections using ultrasonic sensor

The method and apparatus of the present invention will provide a means for a tank owner to determine the time until the next out-of-service API 653 internal inspection of an aboveground storage tank (AST) or an underground storage tank (UST) should be considered or performed based on in-service measurements of the tank filled with fuel or another liquid. The inspection interval is determined from a leak detection test with a pass and a probability distribution of the survival rate of the tank bottom that is representative of the tank being inspected. More accurate estimates are obtained by using measurements of the thickness and corrosion rate of the tank bottom at one or a few locations in the tank and the results of an acoustic emission (AE) corrosion activity test and/or previous out-of-service inspection measurements of the tank floor bottom thickness of the floor at many locations. The method is based on the concept of equivalent risk.

Method and apparatus for determining the time between internal inspections of a tank

A method and apparatuses to extend the time interval between out-of-service, in-tank inspections while insuring structural integrity using a risk-based, Bayesian statistical approach comprised of a passing leak detection test and the using the results from (1) tank floor thickness measurements, (2) prior out-of-service tank floor inspection results, and/or (3) acoustic emission corrosion maps of the tank floor to estimate the minimum thickness and maximum corrosion rate of the tank during the extension period. The present invention uses an in-tank, mass-based leak detection system to establish tank integrity, three or more ultrasonic (UT) thickness measurement sensors for measurements of the tank floor at one location, and to establish the spatial distribution of corrosion of the tank floor, one or more prior API 653/12R1 or STI SP001 tank floor thickness inspections and/or three or more in-tank AE sensors mounted inside the tank with vertical and horizontal locations in an oblique plane relative to the tank floor.

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Tipp City, OH, United States of America

Douglas W Mann