Studies on the Behavior Some Paints in Electro-insulating Fluid Based on Vegetable Esters

Abstract

For the purpose of using three different types of painting materials for the inner protection of the transformer vats, their behavior was studied under actual conditions of operation in the transformer (thermal stress in electro-insulating fluid based on the natural ester in contact with copper for electro-technical use and electro-insulating paper). By comparing determination of the content in furans products (HPLC technique) and gases formed (by gas-chromatography) in the electro-insulating fluid (natural ester with high oleic content) thermally aged at 130 �C to 1000 hours in closed glass vessels, it have been found that the presence the investigated painting materials lead to a change in the mechanism and kinetics of the thermo-oxidation processes. These changes are supported by oxygen dissolved in oil, what leads to decrease both to gases formation CO2, CO, H2, CH4, C2H4 and C2H6) and furans products (5-HMF, 2-FOL, 2 -FAL and 2-ACF). The painting materials investigated during the heat treatment applied did not suffer any remarkable structural changes affecting their functionality in the electro-insulating fluid based on vegetable esters.

Ageing of Some Painting Materials Subjected to Thermal Treatment in Natural Esters

“…As for images a), b) and c) of figure 3, one may notice that, further to the thermal treatment, the morphology of the surface of the PM-3 samples is significantly changed, which suggests that the painting material underwent structural/ composition changes -these changes may explain the evolution of the pull-off test values shown in Table 2 and, respectively, the chemical behavior of PM-3 (which is different from PM-1 and PM-2 samples) by formation of gases and furanic compounds [38] and, also, the evolution of pH (acidity) and humidity [39] of the investigated oil under thermal stress working conditions. 1.…”

“…A particular case, which is relatively less studied until now, is the case of the interaction between the polymeric painting systems and the electro insulating fluids inside of the electrical transformers tanks, under the thermal, electrical and chemical stress [38,39].…”

“…Inside of the electrical transformers tanks, the painting materials are exposed to the thermal ageing through the thermo-oxidative processes with the participation of the oxygen which is dissolved in the electro insulating fluid (transformer oil) [38] and further to the interaction with the transformer oil [38,39]. Under these circumstances, can be observed, on one side, the degradation of the coating (which may lead to the exfoliation of the coating and to the failure of the combined insulation system oil / Kraft insulation paper of the transformer itself) and, on the other side, to the degradation of the transformer oil and of the electro insulating paper.…”

Assessment of Paint Layers Quality 3. Analysis by SEM-EDAX and XRF techniques of the paint layers applied on a railway bridge

“…They degrade relatively fast both by top coat degradation and by intense increases of biofouling.The metal structures durability and safety in exploitation are complex issues from theoretical point of view, but also with material, social and, ecological significant implications.The theoretical complexity of the issues arises from the special diversity of the stress factors acting synergistically on the metal structures and the protection systems provided.Depending on the operating environment during exploitation, the metal structures and the anti-corrosion protection systems with which they are provided are exposed to a number of stress factors such as: mechanical (vibration, trepidation, etc. ), thermal [1, 2] climatic [3-6], non-ionizing radiation in IR and / or UV spectrum [2,4,6,7], chemical [8][9][10][11][12], microbiological [14-25] etc.Under concerted / simultaneous and synergistic action of stress factors, corrosion protection films (usually polymeric) are ageing and lose their anti-corrosion protection capability [15].After the first corrosion germs appear under the paint layer the process is substantially accelerated -firstly in the joining zones (screws, welds, etc., fig. 1 and fig.…”

“…Depending on the operating environment during exploitation, the metal structures and the anti-corrosion protection systems with which they are provided are exposed to a number of stress factors such as: mechanical (vibration, trepidation, etc. ), thermal [1,2] climatic [3][4][5][6], non-ionizing radiation in IR and / or UV spectrum [2,4,6,7], chemical [8][9][10][11][12], microbiological [14][15][16][17][18][19][20][21][22][23][24][25] etc.…”