Selection of an inhibitor for corrosion protection of the inter-pipe space of the underwater transition of the “Pavlodar – Shymkent” oil pipeline through the Irtysh river

Abstract

The article presents a study of the protection degree of a model inhibiting solution samples in order to select the optimal inhibitor for protecting the annular space of the underwater crossing of the “Pavlodar-Shymkent” main oil pipeline across the Irtysh river built by the pipe-in-pipe method. In order to determine the corrosion rate of pipe steel we used witness coupons made of 17G1S steel similar to the steel of the pipeline in operation. Gravimetric and electrochemical methods were used to study the inhibitory properties of inhibiting solutions consisting of corrosion inhibitors Rancor 1101, CRW 82590, VpCI 337, ForeRP 40, and water from the Irtysh river. We carried out comparative analysis of the corrosion rates of pipe steel and the protection degree of inhibitor solutions at various concentrations. Any of inhibitors in concentrations from 50 to 750 ppm, in static mode, do not provide a protective effect, at which steel 17G1S shows increased resistance in a corrosive environment of water samples from the river Irtysh (reduction of the average corrosion rate to 0.005 mm/year according to GOST). Comparing the protective ability of corrosion inhibitors in a corrosive environment from water samples from r. Irtysh, it has been exhibited that the Baker Hughes inhibitor CRW 82590 shows the best protective ability, in static mode during gravimetric studies 80,38% (500 ppm) and 82,52% (750 ppm), in static mode during electrochemical studies 85,90% (500 and 750 ppm).