Non-destructive welded joints of inner-coated steel pipes in long-distance pipelines

Abstract

The invention discloses a lossless welding connector for a long-distance pipeline steel pipe with an internal coating. The lossless welding connector comprises a flaring welding connector and a necking-down welding connector which are in inserted welding with each other. The two welding connectors are provided with end walls with a certain thicknesses, the inside of the flaring welding connector and the top of the end wall of the necking-down welding connector are provided with leading-in grooves in inserted matching, the top of the end wall of the flaring welding connector and an outer wall of the necking-down welding connector are provided with welding grooves matched with each other, and the flaring welding connector is provided with an injection port and an overflow port. The welding connector does not reduce the diameter of a pipeline, the heat conduction characteristics of the pipeline are utilized, the temperature of a pipe body is reduced by circulation of a heat exchange carrier in the pipeline, the anti-corrosive internal coating is protected, and lossless welding is achieved.

Description

technical field [0001] The invention relates to a non-destructive welded joint of an inner-coated steel pipe of a long-distance pipeline, and belongs to the technical field of welded joints with anti-corrosion inner-coated pipes. Background technique [0002] In oil, natural gas, coal slurry, coal bed methane, water industry and other technical fields, long-distance transportation has extremely strict requirements on pipes, and the combination of long-distance transportation pipes is usually a long-distance pipeline. Long-distance pipelines are a combination of steel pipes. When transporting oil, natural gas, water or severely corroded fluid media, it is necessary to add an anti-corrosion coating on the inner wall of the steel pipe to prevent the corrosion of the pipe by the fluid medium transported by the pipe. In the existing technology Among them, when pipes with internal anti-corrosion coating are welded and connected to long-distance pipelines, it is necessary to reserv...

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Problems solved by technology

[0003] Although with the continuous development of the industry, industrial pipeline robots can be used to enter the pipeline for joint repair and coating repair, but it is only a symbolic repair of the welding part, but it is difficult to achieve the quality level of the factory prefabricated anti-corrosion layer

There are many disadvantages in construction site jointing and coating repair: First, the process and quality are difficult to monitor, especially the quality of rust removal is difficult to reach the level of factory operations, which will inevitably affect the key performance of the anti-corrosion coating - adhesion; Second, the surface of the factory-coated anti-corrosion layer is smooth and dense, and the overlap between the repair coating and the original anti-corrosion layer is prone to delamination and peeling off; third, all special powder anti-corrosion coatings resistant to high temperature, high pressure, high corrosion and low temperature are Special curing and plasticization is required, and there is no way to complete on-site repairing, resulting in weak points of anti-corrosion, forming a wooden barrel effect, and greatly reducing the service life of the pipeline

[0004] In order to reduce the inner joint, the more commonly used is the lining coating joint sleeve. Although it can effectively compensate for the joint defect, it also has the problem of affecting the diameter of the pipeline. Generally, the wall thickness of this type of joint sleeve is about 10- 14mm, if calculated on the basis of a steel pipe with a diameter of 114.3mm, the diameter is reduced by 20%, and the flow field of the conveying medium at both ends of the connecting sleeve changes, which is prone to eddy currents, the local diameter is reduced, the flow rate is increased, and local erosion is aggravated, which is easy flow field corrosion

And due to the change of the local diameter, the resistance increases, resulting in a decrease in the delivery volume

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