Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
EFFECT OF SILICA ADDITION IN THE ADHESIVE PRIMER LAYER OF COMPOSITE SYSTEMS USED TO REPAIR LEAK DEFECTS IN PIPELINES
Submission Author:
Heraldo da Costa Mattos , RJ , Brazil
Co-Authors:
Camila Ranucci de Luca, Mauro Jorge Rocha FIlho, João Marciano Laredo dos Reis, Heraldo da Costa Mattos
Presenter: Heraldo da Costa Mattos
doi://10.26678/ABCM.COBEM2023.COB2023-2138
Abstract
Fibre reinforced polymer composites are often used to repair through-thickness corrosion damage in metal pipes. Usually, a primer adhesive layer is initially applied to the surface of the pipe and then the composite reinforcement is applied in concentric layers. This paper investigates the possibility of adding silica as a low-cost thixotropic thickener to a commercial epoxy resin to facilitate the application of the prime layer while maintaining the strength and effectiveness of the repair after curing. The study of the influence of the silica concentration on the rheological behaviour of the adhesive before fully cured was performed using a rheometer. Hydrostatic burst tests were carried out on specimens with through-thickness defects, repaired using the same composite, but with two different initial adhesive layers (same surface finish and layer thickness, but with silica and without silica). The study shows that introducing a low fraction of silica facilitates the application of the primer and does not significantly affect the strength of the repair. The introduction of a small fraction of silica powder (1% by weight) in a commercial adhesive increases its apparent viscosity, facilitating its application as primer layer adhesive (an adhesive used in some repair systems to bond the composite laminate to the substrate) on the surface of corroded pipelines. This is particularly important in the repair of leakage defects in complex positions. The adhesive becomes fluid and easy to handle as it is applied to the pipe surface but becomes a gel when left undisturbed. Because of these qualities, this adhesive is less likely to drip from a brush than the adhesive without silica. Besides, the silica does not affect severely the mechanical performance of a composite repair system after the resin is fully cured. This thickener has proved to be remarkably effective in imparting thixotropic properties to coating masses. In the case of through-wall defects, the failure pressure is lower when using silica in the primer layer adhesive. However, this can be easily circumvented by increasing the thickness of the composite repair. Another interesting remark is that all the main conclusions in this paper apply for pipe repairs using bonded metallic or composite patches instead of composite gloves. The addition of such a low-cost thixotropic thickener makes the application of the adhesive layer in composite repair systems easier while maintaining good adhesive properties and avoiding leaking.
Keywords
Through-thickness defects in pipelines, composite repair systems, Primer layer, thixotropic thickener, Silica Powder, Failure pressure
