METHOD FOR ASSESSING THE RESISTANCE OF PIPELINE STEELS TO "GROOVING" CORROSION Russian patent published in 2021 - IPC G01N17/00 C23F13/00 

FIELD: corrosion protection.

SUBSTANCE: invention relates to the field of corrosion protection of field oil pipelines operating under the simultaneous influence of an aggressive environment, mechanical stresses and abrasive particles, and can be used to assess the resistance of pipeline steels to "groove" or "ridge" corrosion. The method includes making a plate from the analyzed steel, bending the plate in the bracket to the required deflection arrow, while the length and the residual deflection arrow of the plate are taken in a ratio that ensures the occurrence of the level of residual stresses in the pipeline at the midpoint of the plate at the midpoint of the plate with on the inner side across the length, a rounded incision is made with a radius of 0.5 mm and a depth of up to 0.3 mm, installing the plate in a horizontal position with the notched side down in a thermostat with an aggressive medium, which is an aqueous solution of NaCl with a concentration of 2 to 3%, thermostating at a temperature of 55 to 65°С for 5 to 50 hours with an air flow to the place of the notch and fixing the exposure time, while the surface of the plate around the notch is covered with a protective varnish, which is removed before measurements, and the depth of the notch before Н_i and after Н_i* exposure to the environment is determined at n ≥10 points along its length, in this case, the plate is placed under an optical microscope and the distance between the bottom of the notch and the surface of the plate is measured by fine focusing, then the change in the depth of the notch ∆Н_i at each point is determined as ∆Н_i = Н_i* - Н_i, as a result of the corrosive effect of the environment, then the average change in ∆Н_av is determined, as ∆Н_av = ΣΔНi / n and calculate the corrosion rate by the formula K = (∆Н_av / t) 8760 [mm / year], where ∆Н_av, mm, t is the thermostating time, hour, 8760 is the number of hours per year.

EFFECT: development of a method for assessing the corrosion resistance of pipeline steels under conditions of simultaneous exposure of the pipe to an aggressive environment and mechanical stresses.

1 cl, 7 dwg, 2 tbl