An enhanced method for determining the maximum strain a pipeline coating could tolerate

An enhanced mandrel bend testing method has been proposed for the evaluation of the maximum strain level that could be tolerated by an organic coating, and for the understanding of localised coating deformation and cracking behaviours under nonuniform mechanical strains. The aim is to develop a practical method that is suitable for selecting pipeline coatings in order to ensure that the selected coatings have sufficient flexibility to meet the high strain demand during the construction, hydrostatic testing and operation of high pressure pipelines. Two new mandrel bend testing setups have been designed by employing either centre or end clamps in order to improve the uniformity of strain distributions over coated steel coupons, and by using strain gauges to perform in situ measurements of local strains. A series of tests have been carried out to evaluate the new method for testing the flexibility of selected epoxy based pipeline industry coatings. Preliminary computational simulation has also been carried out for assisting the interpretation of mandrel bending test results.