Parametric optimization for rehabilitation of pipes with adhesive bonding

Abstract

This work deals with the optimization of process parameters for rehabilitation of the pipe through-wall hole defects using adhesive bonding. Epoxy-based nonstructural adhesive (NSA) and structural adhesive (SA) combination, precure temperature, bond length, and surface preparation were considered as the parameters. The optimization of parameters directly on pipes is an expensive and time-consuming process. Hence, stainless steel and carbon fiber-reinforced polymer (SS-CFRP) composite single-strap joint was considered. The equivalent loads that were acting during the hydrostatic pressure test were applied to the SS-CFRP joint and its parametric effect on bond strength was studied. The stress distribution along the adhesive layer length has been derived analytically. The surface roughness of prebond surfaces was measured using a 3-D microscope. The quality of the adhesive bond was evaluated using nondestructive testing (digital radiography). The damaged pipe was rehabilitated with optimized parameters and its hydrostatic pressure resistance was tested according to ISO/TS 24817 standards. From the results, it is observed that the rehabilitated pipe with optimized parameters was able to sustain a maximum of 79% of its allowable pressure.