Rehabilitation of corroded pipes that are used for marine applications working under internal pressure is not only difficult task but also produces large amount of waste. In this paper, the repairing process of underwater steel pipes with woven glass fiber reinforced epoxy composites is studied. ASME PCC-2 and ISO-24817 are the only available design codes for the design of such repair system. These two codes suggest calculating the minimum composite repair thickness for a given design pressure based on the diameter of the pipe, its wall thickness and composite allowable strain. It was observed that the diffusion coefficient of the glass fiber-epoxy composite laminate increased with time of sea-water exposure. After 40 days of immersion of this laminate in sea water at 85°C, 43.4% reduction in strength & 14.9% reduction in modulus were observed. The hoop stresses in repaired pipe before and after dipping were increased from 288.64 MPato 357.89 MPa, suggesting a need for higher composite repair thickness for complete rehabilitation. A satisfactory agreement between numerical and experimental results is obtained © 2019 Elsevier Ltd.