Sleeve for in-service welding with reduced hydrogen cracking tendency

Abstract

The invention discloses an in-service welding sleeve. The in-service welding sleeve comprises a sleeve body and a heating belt; the heating belt serves as a weld preheating assembly and a postweldingheat insulation device and cooperates with the sleeve body, and the inevitable hydrogen cracking phenomenon in the welding process is decreased through the weld preheating treatment and postwelding heat treatment; the sleeve body is welded to a position needing to be repaired so that leakage can be stopped or a pipeline can be reinforced, a gap is reserved between the sleeve body and the pipelineand filled with high-pressure inert gases, the force borne by the pipeline can be reduced, in addition, the inert gases in the gap are stable in performance, and the situation that the pipeline is subjected to external corrosion can be avoided; and accordingly, the service life of the pipeline is prolonged, and the repaired pipeline can continue being in service for a long time.

Description

technical field [0001] The invention belongs to the field of pipeline welding, and in particular relates to an in-service welding sleeve which reduces the tendency of hydrogen cracking. Background technique [0002] During the long-term service of oil and gas pipelines, it is inevitable that corrosion and perforation will cause leakage and pipeline damage. Failure to deal with it in time may cause many serious problems. Therefore, it is necessary to strengthen and repair the weak or leaking parts of the pipeline. For oil and gas pipelines, welding cannot be stopped. In addition, hydrogen-induced cracking (hereinafter referred to as hydrogen cracking) is also one of the important reasons for the failure of welds. If the above two problems cannot be solved well, a good repair effect cannot be achieved. [0003] The in-service welding process provided by the existing technology mainly includes two types, one is the sleeve repair, which is to weld the sleeve outside the damaged ...

AI Technical Summary

Problems solved by technology

[0005] In the existing technology, methods such as low-hydrogen electrode, tempering bead process, and medium-frequency induction heating are often used to reduce the cooling rate and hydrogen source intake to reduce the impact of hydrogen cracking; the Chinese invention patent with application number 201810360208.2 proposes An in-service welding method for gas pipelines is proposed. This invention integrates the two methods of the prior art, and reduces the flow velocity in the main pipe by rebuilding branch pipes, thereby reducing the cooling rate. The remaining steps are similar to the prior art. However, this method needs to build branch pipes, which increases the operation steps, and because the pipeline fluid is flowing, the heat loss is still very serious

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