EFFECTIVENESS OF UNLOADING NPP PIPELINE SECTION WITH A PIPE WALL THINNING DEFECT BY MOUNTING A BAND OR A WELDED COUPLING.

Formation of erosion-corrosion wear defects in Npp pipelines is one of the urgent problems of nuclear power engineering. During pipeline repair, a defective section is cut out and a new pipe spool is mounted using welding, which is a rather labour-consuming process, and requires draining of the transported liquid. To prolong the service life, a defective pipeline section can be reinforced by mounting a repair structure, for instance a band or a welded coupling. In order to substantiate the rationality of application of reinforcing structures in pipeline repair, the finite element analysis of the stress-strain state of a rectilinear pipeline section with an erosion-corrosion wear defect under the impact of internal pressure, as well as evaluation of the effectiveness of unloading a defective section in the case of application of a reinforcing structure of the type of a band or a welded coupling in repair were performed. The analysis results have shown a high effectiveness of applying such structures. The obtained results can be used in substantiation of introduction of alternative technologies for repair of pipelines in the Ukrainian NPP, predominantly technological ones, particularly in those cases when repair by traditional methods is not possible or rational for technical or economic reasons. [ABSTRACT FROM AUTHOR]