Aboveground Storage Tank Floor Corrosion Condition Assessment

Resumen

The floors of aboveground storage tanks remaina most difficult part of the vessel to inspect forcorrosion damage. Generally, this section of the tankis inaccessible from the outside for conventionalnondestructive testing (NDT) and the costs ofopening the vessel and preparing it for an internalinspection including cleaning, purging and loss ofproduction availability create a significant financialburden for the tank owner or operator. An advancedNDT method with the capability of assessing thecondition of the tank floor without opening thetank is acoustic emission (AE) monitoring1. The AEmethod requires installation of sensors on the outsidewall of the tank and monitors the floor passively forcorrosion damage and its extreme case of leakingat substantially lower cost. AE monitoring is afront-line inspection method that complements theinternal inspection techniques. When it is integratedas an input to a risk-based maintenance program, itprovides both an enhanced level of tank reliabilityand significant cost savings over time-basedperiodically scheduled internal inspections2,3. Thispaper provides an overview of the AE inspectionmethod as applied to tank-bottom plate conditionassessment, a brief description of its use in a riskbasedmaintenance program including a case studyof the practical use of AE monitoring for tankbottom inspection.