Development of nano filler reinforced semi-solid rapid curing sealant paste for through-thickness leaking defect repair in pipelines

The present paper discusses the development of a Semi-solid Rapid Curing epoxy Resin-based (RaCER) sealant paste using micro and nanoscale fillers and curing agents. Semi-solid consistency and rapid curing behaviour are two essential criteria for a RaCER sealant paste to be qualified to be applicable for repairing leaking defects in oil and gas pipelines. RaCER is a two-part system consisting of a resin-based paste (Part A) and a curing agent-based paste (Part B). The compositions of the micro and nano fillers in Part A and Part B and the amount of curing agent in Part B vary to achieve the required semi-solid consistency and optimum curing time. The optimization of micro and nanofiller compositions and curing agents is done with the help of statistics. A mathematical model for the response of these variables curing time, tensile, compression, and shear strength, is developed using a full factorial design of experiments. The optimum composition is derived using response surface methodology. Hydrostatic burst tests on pipe specimens with 10 mm through hole defect repaired in the live and non-live conditions are conducted to evaluate the performance of RaCER paste. An enhanced repair methodology is also evolved for repairing large-size leaking defects and sealing the leak in live condition. The failure pattern and enhanced pressure-bearing capability of the epoxy resin-based sealant paste indicate better interfacial bonding with steel and Glass Fiber Reinforced Polymer (GFRP) substrates, making the product suitable for oil and gas pipeline repair compared to other commercially available products.