CFRP Repair and Strengthening of PCCP for Thrust Restraint

Design of carbon fiber reinforced polymer (CFRP) repairs for pipes near bends requires consideration of longitudinal stresses resulting from hydraulic thrust-induced axial forces and bending moments, temperature changes, and Poisson's ratio effect of circumferential strain. In addition, CFRP strengthening of the thrust restraining system may be required due to increased pressure resulting from change in demand. CFRP composites offer significant advantages in such applications, as it does in typical circumferential repairs, such as eliminating the need for replacement of the pipe near the bend or access for external repair, as long as all longitudinal load effects are properly determined by analysis and accounted for in design. Longitudinal repair with CFRP also requires special end termination details to ensure proper transfer of stresses into the CFRP liner. This paper presents the results of the experience gained in design of CFRP liners and their terminations for longitudinal forces determined from analysis.