DETERMINATION OF FLOW STABILIZATION ZONE IN PIPELINE CORROSION RATE MEASURING DEVICES

Analysis of corrosion damage of interfield product pipelines showed that the corrosion rate in the pipeline is not uniform not only along the length and technological zone (flow and dead-end lines), but also along the distribution in the cross section of the pipe in the pipeline (upper, lower and side segments). Therefore, recently, special devices with four witness samples installed in the upper, lower and side segments of the cross section of the pipeline have been used to determine the corrosion rate on interfield product pipelines. The paper examines the effect of medium velocity on the flow stabilization zone in these special devices for measuring flow velocity when determining corrosion-erosion wear of pipelines. It is shown that these devices do not provide controlled conditions for hydrodynamics and mass transfer similar to the conditions in the controlled pipeline, which does not allow to correctly predict its residual life. So for pipelines DN 80 flow stabilization occurs only at a distance of 0,234 m from the entrance to this device, and for pipelines DN 100 at a distance of 0.294 m. This is more than 3 times the length of the current flow velocity measuring devices, which is 0.073 m for DN 80 and 0 for DN 100.071 m. Accordingly, witness samples of these devices are located in an area with unstable flow parameters, which does not allow to correctly determine the rate of corrosion-erosion wear of the pipeline based on the data of witness samples.A method for calculating the flow stabilization zone in special devices with witness samples in conditions of corrosion-erosion wear is proposed, which allows determining the required length of the device and the zone for mounting witness samples. Based on calculations performed in SolidWorks Flow Simulation, it is proposed to extend these devices for the pipeline DN 80 PN 40 to 0.4 m, for pipeline DN 100 PN 40 up to 0.5 m. This will allow to shift witness samples from the inlet flange for pipeline DN 80 PN 40 by 235, 295 mm DN 100 PN 40 for the pipeline and ensure flow stabilization, respectively, approximate the conditions of corrosion-erosion wear of witness samples and the pipeline itself.