METHOD OF DETEREMINATION OF THE SERVICE LIFE OF THE ANTICORROSIVE PROTECTIVE COATINGS FOR THE UNDERGROUND STEEL PIPELINES Russian patent published in 2006 - IPC C23F13/00 

FIELD: ferrous metallurgy; methods of production of the external anticorrosive protective coating for the subterranean steel pipelines.

SUBSTANCE: the invention is pertaining to the methods of the non-destructive inspection of the subterranean pipelines steel insulated pipes and may be used for the mass test determination of the service life of the various types external anticorrosive protective coatings of the subterranean steel pipelines of the designed for operation in the conditions of the hostile medium at the close location from the ground surface of the ground waters of the various mineralization and elemental composition. The method provides for: seasoning of the samples of the prototype pipes with the diameter of 89 - 400 mm and the length of 600 - 1000 mm within seven days after their manufacture first - in the open air under the conditions of their warehousing; then - in the liquid hostile medium imitating the subterranean ground waters; determine - in the equal time intervals within up to three years of the period of the prototype samples seasoning in the hostile medium - the integral index of the quality, reliability and durability - the transitional electric resistance of the coating by the standard method of "the wet contact"; ascertain the dependence of variations of the transitional electric resistance of the coating on the time period of their staying in the hostile medium; and define the service life of the external anticorrosive protective coating of the steel pipelines from the following expression: T = β(k-ρ₀/ρ_n)^1/α , where T - the service life of the pipelines coating (years); β - the factor of dimension, β=0.083 year/month; α - the experimentally ascertained factor characterizing the intensity of the pipeline coating aging at operation in the concrete conditions of the hostile medium, α = 1-2; k - the coefficient of proportionality, month; ρ₀ - the transitional electric resistance of the coating after its seasoning in the hostile environment within one month, Ohm·m²;_{ρn - the least admissible normative transitional resistance of the pipelines coating in the process of operation, Ohm·m². The technical result of the invention is the rise of accuracy and reliability of determination of the life service of the external anticorrosive protective coating of the subterranean steel pipelines designed for operation in the conditions of their underflooding by the aggressive ground waters.}

EFFECT: the invention ensures the rise of accuracy and reliability of determination of the life service of the external anticorrosive protective coating of the subterranean steel pipelines designed for operation in the conditions of their underflooding by the aggressive ground waters.

3 tbl, 1 dwg