Method for controlling corrosion under thermal insulation layer

Abstract

The invention provides a method for controlling corrosion under a thermal insulation layer. The method includes the following steps: 1) preparing paint, wherein the thermal conductivity of a coating formed by the paint needs to be smaller than or equal to 0.05 [W / (m.K)], the decontamination rate of the coating formed by the paint is larger than 95.0%, and the contamination sensitivity rate is larger than 4.5%; 2) applying the paint, wherein the paint is applied to the surfaces of pipelines and equipment, the coating is formed after the paint is dried, and the thermal insulation layer is installed on the surface of the coating; 3) installing a corrosion monitoring device, wherein the corrosion monitoring device comprises metal coupling electrodes, a signal transmitter and an indicator, andthe metal coupling electrodes are installed on the surface of a metal substrate, in the coating and in the thermal insulation layer in the construction process; and 4) performing corrosion monitoring,wherein current signals of the metal coupling electrodes are transmitted to the signal transmitter, the signal transmitter receives the current signals and amplifies the current signals, and the indicator is driven to display the current signals. The method for controlling corrosion under the thermal insulation layer can provide an effective basis for the strategy of maintenance under the thermalinsulation layer, and the purpose of controlling corrosion of the metal substrate is achieved.

Description

technical field [0001] The invention relates to the technical field of corrosion and protection of pipeline equipment in nuclear power plants, in particular to a method for controlling corrosion under insulation layers suitable for nuclear power plant environments. Background technique [0002] Corrosion under insulation (CUI, corrosion under insulation) refers to a corrosion phenomenon that occurs on the outer surface of pipes or equipment with insulation materials applied. Insulation materials usually have a loose and porous structure with a large specific surface area, so they have a strong water absorption capacity. Due to insulation design defects, mechanical damage, maintenance problems, etc., water vapor will gradually enter the insulation layer. Most insulation materials are inorganic substances, which contain a large amount of chloride, fluoride, sulfide, etc., which will promote metal corrosion. [0003] In the prior art, there are two ways to solve the problem of...

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Problems solved by technology

[0003] In the prior art, there are two ways to solve the problem of corrosion under the insulation layer: one is to improve the performance of the insulation layer, such as selecting insulation materials with low water content and fast drying, to enhance the performance of the protective layer to prevent moisture from entering Insulation layer, but there is no insulation layer that can completely isolate moisture in practical applications. At the same time, due to design defects or insulation installation and maintenance problems, moisture directly enters the insulation layer

The second is to apply ordinary anti-corrosion coatings on the metal surface, but due to the performance factors of the coating itself, such as the thermal expansion coefficient is different from that of the metal, the thermal cycle will often lead to an increase in the internal stress of the coating, which will eventually cause early failure of the coating. It cannot effectively solve the corrosion problem under the insulation layer

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