Dealuminification of heat exchanger tubes. (November 2019)

• Record Type: Journal Article
• Authors: Pelliccione, A.S.; Silva, L.S.; Silva, F.L.M.C.; Silva, O.P.
• Is Part Of: Engineering failure analysis. Volume 105(2019)
• Page Start: 970
• Page End: 981
• Publication Date: 2019-11
• Subjects: Dealloying -- Dealuminification -- UNS C61400 -- Aluminum bronze -- Heat exchanger -- Tube; System failures (Engineering) -- Periodicals; Fracture mechanics -- Periodicals; Reliability (Engineering) -- Periodicals; Pannes -- Périodiques; Rupture, Mécanique de la -- Périodiques; Fiabilité -- Périodiques; Fracture mechanics; Reliability (Engineering); System failures (Engineering); Periodicals; Electronic journals; 620.112
• DOI: 10.1016/j.engfailanal.2019.07.052
• Languages: English
• ISSNs: 1350-6307

Abstract

Abstract: This paper presents a failure analysis of heat exchanger tubes manufactured from aluminum bronze. The equipment operates as an intercooler after the first stage compression. The cooling medium was seawater that passed inside the tubes. The investigation involved visual inspection, chemical analysis, metallography, hardness test, scanning electron microscope analysis, and thermal-hydraulic evaluation. The aluminum content of the analyzed tube was higher than the maximum value defined by the design specification ASTM B111 C61400. The high aluminum content promoted γ2 phase formation that was preferentially attacked from the tube inner surface. The tubes failed due to dealloying (dealuminification) associated with under-deposit corrosion in regions of higher temperatures and lower seawater velocities. Highlights: Failure of aluminum bronze tubes due to plug-type dealloying (dealuminification), associated with under-deposit corrosion. High aluminium content of the tubes material, promoting aluminum-rich phase (γ2 ) formation. Multi-disciplinary study, including optical metallography, SEM/EDS analysis, SEM/EBSD analysis and thermal-hydraulic simulation. Selective attack of γ2 phase as evidenced by metallography and SEM/EDS analysis. Coherency between the tubes failure locations and the results of thermal-hydraulic evaluation.