<p>Glass-fiber reinforced polymer (GFRP) composites pipes are increasingly opted as an alternative to metallic pipes for transportation of crude oil due to their high specific strength, superior corrosion resistance and tailor-made properties. However, during transportation of crude oil, paraffin deposits over the inside pipe surface, reducing the cross-sectional area and affecting the performance. Therefore, an effective methodology for real-time measurement of thickness of wax deposition on the inside of a smart GFRP circular pipe is explored. The proposed approach employs sensors i.e. Fiber Bragg grating (FBG) sensors, strain gauges and thermocouples which are embedded during manufacturing to monitor the real-time temperature and strain under operating condition. Water at varying temperatures and flow rate is circulated through the pipe and the resulting temperature gradient along the thickness are measured. As wax builds up, it acts as an insulating layer, reduces heat transfer and results in a measurable temperature drop. This temperature drop is correlated with the thickness of wax deposition in the pipe using heat transfer equations, provided the film heat- transfer co-efficient is calculated accurately. Additionally, the strain is recorded on real-time basis which increases linearly with the thickness of deposit. While the temperature-based estimation may under-predict thin wax layer due to little change in outlet temperature, strain measurements offer great sensitivity even to a minor deposition. Strain data also helps to locate the place of deposition along the pipe axial length. This dual parameter monitoring strategy enhances the reliability and accuracy in estimating wax thickness without disruption.</p>