Measuring the Remaining Strength Factor of a Steel-Adhesive-Repair System

A new repair-reinforcement system to be utilized on pipeline showing external metal loss was developed and tested by employing scaled models in order to verify the system’s effectiveness in reestablishing pipeline structural integrity. The repair system is composed of pre-curved thin layers of steel lamina, which are set in place on the external metal loss defect area of a pipe and cemented in place with epoxy resin. Hydrostatic burst tests were performed on three types of pipe specimens: with metal loss defects, without metal loss defects and with metal loss defects but repaired with the new system. Strain gages were used to monitor elastic and plastic strains during the tests. Test results, burst pressures and pressure-strain curves were compared using simple analytical equations that were developed to determine the number of thin steel layers to be used in the system and to model the behavior of each tested specimen. The investigation reached the conclusion that the simple analytic equation is effective for determining the required repair thickness and its number of layers, that the repair system reconstructs pipe integrity and that it should be further investigated as to applying it while the pipeline is still in operation.