A small percentage of the protective interior topcoat in B-52 integral wing fuel tanks is failing. Two separate modes of failure are observed. On vertical surfaces, fragments of paint detached from the aluminum contain frozen in wrinkles, striations and channels. On the floor of the fuel tank, paint detached from the aluminum is flat and featureless. In this first communication, the BMS10-39 epoxy paint is structurally characterized, with emphasis on the detection of elements of chemical degradation. A preliminary model is then developed for the delamination process operative on vertical surfaces, as supported by interactions of the coating with diethylene glycol monomethyl ether (DIEGMEa fuel system deicer used in military jet fuel) in high temperature distillates from JP-8 jet fuel; and for the delamination process operative on the floor of the fuel cell based on interactions of the paint with mixtures of water and DIEGME. Preliminary results indicated that removal of paint from the floor of the fuel cell could be due to exposure of the paint to mixtures of DIEGME and water in which the DIEGME level exceeds about 50 vol.%. To generate a margin of safety, and perhaps minimize loss of paint from the floor of the fuel cell, water should be drained from the fuel cell before the DIEGME level reaches about 40 vol.% in the water. Based on the location of failed regions on vertical surfaces in the B-52 fuel cell, and an analysis of the paint and the jet fuel, a failure process based on the interaction of DIEGME enriched distillates from the fuel with the paint was proposed and defended using model systems generated by high temperature distillation from the fuel. These studies must be confirmed by showing that material evaporated at lower temperatures from JP-8 fuel is enriched in DIEGME, and that said distillate is able to swell significantly BMS10-39 epoxy paint.
Epoxy paint failure in B-52 fuel tanks. Part I - Preliminary development of a model for the process
Beschädigung der Epoxidharzbeschichtung in B-52-Treibstofftanks. Teil I: Entwicklung eines vorläufigen Prozessmodells
Progress in Organic Coatings. An International Journal ; 56 , 4 ; 285-296
2006
12 Seiten, 11 Bilder, 14 Quellen
Aufsatz (Zeitschrift)
Englisch
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