NDTsi 2001 Session: Major Component Inspection I-IV
Eddy Current Characterization of Erosion-Assisted Tube Support Plate Degradations
D. Leimbach, PPL Electric Utilities, USA; N. Muthu, K. Krzywosz, EPRI, USA
ABSTRACT
Balance-of-plant (BOP) heat exchanger condition assessment programs include not only the monitoring of overall heat exchanger performance but also assessing the integrity of heat exchanger tubing and tube support plates through non-destructive and, sometimes destructive evaluation. Tube support plates found in BOP heat exchangers play a vital role in proper component operation and reliability. Recently, EPRI NDE Center developed an eddy current inspection technique that identifies and quantifies various degrees of tube support plate degradation. The test incorporates specialized transmit-receive bobbin probes operating at low to intermediate frequencies to characterize the condition of tested tube support plates. EPRI fabricated several air-transportable mock-up (ATM) bundles that housed both normal tube support plates and eroded support plates that are closely replicated to simulate progressive erosion and thinning of tube support plate thickness. Various sizes and shapes of machined holes represented erosion and vibration damages. These ATM's served to establish a criterion for repair and to provide both qualitative and quantitative information about the tube support plate conditions. Additionally this technique by relying on a higher intermediate frequency channel to detect flaws in the free-span tubing region allowed simultaneous characterization of tubing and tube support plate conditions in one scan. This paper presents results of applying the new eddy current inspection methodology for identifying and quantifying the erosion-assisted tube support plate degradations.
Publication Source: 3nd International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurized Components, November 14-16, 2001, Seville Spain. Publisher: Tecnatom s.a. - [Homepage]
