Solid solution transition close potential stainless steel bead welding method for pre-repairing of steel pipeline welded junction

Abstract

The invention discloses a solid solution transition close potential stainless steel bead welding method for a pre-repairing of a steel pipeline welded junction. The method is used for bead welding of stainless steel on the inner wall at the end of a low carbon steel pipe, in particular to the solid solution transition close potential stainless steel bead welding method for pre-repairing of the steel pipeline welded junction. The method differs from other stainless steel bead welding methods for steel pipeline welded junction pre-repairing and is the solid solution transition close potential stainless steel bead welding method with the premise that good welding performance and inner corrosion prevention performance of the steel pipeline welded junction are guaranteed and corrosion of a bead welding bimetallic cell on the inner wall of the steel pipeline welded junction is prevented. The method is the key technology guaranteeing continuousness of a corrosion prevention layer of the inner wall of a steel pipeline and belongs to one of the main contents of the steel pipeline DGR integrated corrosion prevention technology.

Description

technical field [0001] The invention relates to the technical field of anti-corrosion repairing of the inner wall of welded joints of steel pipes. It is a method for pre-repairing welded joints of steel pipes for solid solution transition near-potential stainless steel surfacing welding, and is a method for surfacing stainless steel on the inner wall of a low-carbon steel pipe end. , especially a steel pipe welding joint pre-filling solid solution transition near-potential stainless steel surfacing method, which is different from other steel pipe pre-filling stainless steel surfacing methods, and is a method to ensure that the steel pipe welding joint is good Welding performance and internal anti-corrosion performance, and the solid solution transition near-potential stainless steel overlay welding method based on the premise of preventing the corrosion of the bimetal battery on the inner wall of the steel pipe weld joint. This method is a technology to ensure the continuity of...

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Problems solved by technology

[0004] Invention patent application number 201510515750.7 discloses a method of anti-corrosion surfacing on the inner wall of steel pipe welding joints for internal repair of pipeline welding joints. The diameter of the pipe end is reduced, and the air-fired solid solution makes the interface between the surfacing layer and the low-carbon steel base metal overlap smoothly, and realizes the purpose of pre-repairing the corrosion-resistant alloy surfacing welding of the steel pipe weld joint, but the surfacing welding part of this method is different from the There is a large potential difference at the interface of unsurfacing low-carbon steel. Once the anti-corrosion coating inside the steel pipe falls off and the bimetallic interface contacts a conductive medium, electrons will be obtained due to the correction of the potential of stainless steel relative to low-carbon steel and become a cathode. Low-carbon steel is relatively stainless steel. If the potential is more negative, electrons will be lost to become anodes, which is manifested as galvanic corrosion at the bimetallic interface; although this method controls the total amount of chromium carbide pinholes through cladding surfacing welding, due to the deep penetration of TIG surfacing welding, in actual operation It is still unavoidable that a large amount of carbon migrates and forms chromium carbide inclusions in the surfacing layer with affinity with chromium in the stainless steel. This chromium carbide pinhole is the main cause of pitting corrosion pits on the surface of the stainless steel surfacing layer.

[0005] The above surfacing welding method does not involve the stainless steel filled short pipe and the solid solution of the stainless steel filled short pipe, and does not involve the control measures for the galvanic corrosion caused by the potential difference of the bimetal interface

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