Preliminary Assessment of End-of-Life Epoxy-Glass Laminates from Large Vertical Fuel Tanks: Technical Function, Thermal Behaviour and Waste Management Implications

End-of-life thermoset composite coatings removed from fuel storage infrastructure represent a difficult waste stream because they combine a cross-linked polymer matrix, glass fibre reinforcement, functional layers and possible contamination from long-term contact with petroleum products. This study presents a preliminary assessment of an epoxy-glass laminate removed from the internal surface of a large vertical diesel fuel storage tank. The work combined a simplified numerical analysis of the technical role of the coating with thermogravimetric analysis and microscopic examination of solid residues after thermal conversion. The numerical results confirmed that the coating had a real reinforcing function, reducing the maximum equivalent stress in the corroded steel shell from 228.80 MPa to 191.85 MPa. TG/DTG analysis showed that the main mass loss of the laminate occurred below 500–600 °C, while the residual mass depended strongly on the process atmosphere. The highest residue was obtained after pyrolysis (28.75%), followed by CO2-assisted conversion (26.17%) and combustion (20.87%). Microscopic observations showed that pyrolysis favoured morphological preservation of the fibrous/mineral fraction, but the glass fibres remained partly associated with carbonised epoxy resin and graphite-containing particles. Combustion removed the organic fraction more completely, but the remaining fibres showed signs of degradation. The results indicate that pyrolysis should be treated as a promising preliminary pretreatment route when morphological preservation of the fibrous/mineral fraction is prioritised, although the retained mechanical performance and phase composition of the fibres were not assessed. The study should be regarded as a thermogravimetric and microscopic screening of a real post-service epoxy-glass coating, supporting preliminary selection of end-of-life management pathways rather than a complete recycling or environmental assessment. By linking the thermal behaviour of a real post-service composite coating with feasible end-of-life pathways, the study contributes to sustainable waste management by supporting more informed decisions on material preservation, energy recovery, industrial co-processing and avoidance of landfilling for difficult thermoset composite wastes.