Effect of metallic sealant thickness on leak arrest and composite repair performance in pipeline systems

This study investigates the combined effect of metallic sealant thickness and composite laminate configuration on the structural performance of pipeline repair systems. A total of 63 experiments were conducted on through-wall defects with diameters of 10.2 mm, 15.2 mm, and 25.4 mm diameters, three metallic sealant thicknesses (3.5 mm, 7 mm, and 10.5 mm) were evaluating under both dry and wet conditions. Additionally, two- and four-layer fiberglass composite overwraps were applied to assess their influence on pressure retention and energy release rate. Results showed that increasing sealant thickness significantly enhanced failure leak pressure, particularly in wet environments, where thinner sealants underperformed. The 10.5 mm thickness consistently delivered the best sealing capability across all conditions. Composite repairs improved performance further, with four-layer systems providing the highest-pressure resistance. However, only a marginal increase in interfacial energy release rate was observed, suggesting diminishing returns beyond a certain layer count. Experimental leak pressures exceeded theoretical predictions from ISO/TS 24,817, indicating the need to update current models. This research provides practical guidance for selecting optimal sealant thicknesses and laminate configurations based on defect size and environmental conditions, offering a more reliable, in-service repair solution for pipelines in the oil and gas industry.