Welding method of pipelines

Abstract

The invention relates to a welding method of pipelines. The welding method specifically comprises the following steps that preheating is performed as follows: when the temperature of the environment where the pipelines are located is lower than 0 DEG C, to-be-welded openings of the pipelines and surrounding pipes are preheated to the specified temperature; welding is performed as follows: sealed welding is performed on the to-be-welded openings in the circumferential directions of the pipes; and heat preservation is performed as follows: heat preservation treatment is performed on welding lines formed in the to-be-welded openings and the surrounding pipes, so that the temperature of the welding lines and the surrounding pipes is decreased at the rate not higher than the preset rate until the temperature of the welding lines and the surrounding pipes is decreased below the preset rate. According to the welding method, the temperature of the to-be-welded openings and the surrounding pipes is controlled by the aid of early waste heat and later heat preservation, and the residual stress of the to-be-welded openings and the surrounding pipes is reduced, so that the tensile strength of the welding lines is equivalent to that of the pipes, the problem that cracks appear easily after low-temperature welding is solved, the safe service performance of the heat supply pipelines is improved, and the work and the life of town residents are guaranteed.

Description

technical field [0001] The invention relates to the field of welding technology, in particular to a pipeline welding method. Background technique [0002] With the continuous development of central heating in northern cities and towns, large-scale combined heat and power has gradually become one of the main forms of central heating. Since the distance between thermal power plants and users is generally long, long-distance and large-diameter central heating pipelines have gradually become one of the main characteristics of urban central heating. Due to the long winter and short summer in the north, the construction period is tight and the construction volume is large, so winter construction is unavoidable. Arc welding is an important connection method for long-distance heating pipes. In the cold winter, the heating pipes welded by the usual welding method often have cracks in the weld seam in the first heating season, which leads to the failure of heating pipes. Pipeline le...

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Problems solved by technology

[0003] In order to solve all or part of the above problems, the present invention provides a pipe welding method, which controls the temperature of the joint to be welded and its surrounding pipes through the early waste heat and the later heat preservation, and reduces the residual stress of the joint to be welded and its surrounding pipes, so that The tensile strength of the weld is equivalent to that of the pipe, which solves the problem of cracks after low-temperature welding, improves the safe service performance of heating pipes, and ensures the work and life of urban residents

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