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A kind of pipe joint welding process

A technology of casing joint and welding process, applied in welding equipment, manufacturing tools, arc welding equipment, etc., can solve the problems of pipeline leakage, incomplete cleaning of impurities, and fast cooling speed.

Active Publication Date: 2021-09-10
上海江南船舶管业有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The above-mentioned existing technical solutions have the following defects: if there is a crack in the welded part of the pipe joint, there will be a danger of pipe leakage
The reasons for cracks are as follows: Incomplete cleaning of impurities before welding, excessive current during welding, and excessive cooling speed

Method used

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  • A kind of pipe joint welding process
  • A kind of pipe joint welding process
  • A kind of pipe joint welding process

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] refer to figure 1 , is a casing joint welding process of a pipeline disclosed by the present invention, comprising the following steps:

[0039] S1: Remove oil stains inside and outside the pipe wall. Remove the oil, dust and other impurities inside and outside the pipe wall of the pipe 1, especially the oil left when the pipe is bent needs to be thoroughly cleaned, otherwise there will be bubbles, impurities, cracks in the weld, and the weld will not meet the standard.

[0040] S2: Remove the peeling on the inner wall of casing 2. Use an angle grinding wheel to remove the peeling phenomenon on the inner wall of the casing 2. If the peeling part cannot be completely removed, replace the casing 2 to prevent the generation of low melting point eutectics.

[0041] S3: Sleeve the sleeve 2 outside the end of the pipe 1, and the gap between the sleeve 2 and the pipe 1 is 2 mm. Such as figure 2 and image 3 As shown, when welding, a layer of insulation pipe 3 is placed o...

Embodiment 2

[0048] A casing joint welding process for pipes, the difference from Embodiment 1 is that the gap between the casing 2 and the pipe 1 is 2.5mm. The welding process parameters in step S4 are as follows: first layer: welding current 110A, arc voltage 12V, welding speed 7cm / min, argon gas flow 9L / min; other layers: welding current 130A, arc voltage 15V, welding speed 5.5cm / min min, argon flow rate 11L / min. S7: First remove the cracked weld metal, and use the set low current welding method to repair the cracks in multiple passes. The welding process parameters of the low current welding method are set as welding current 100A, arc voltage 12V, welding speed 7cm / min, argon Air flow 9L / min. In multi-pass repair welding, the next repair welding is performed when the temperature after the previous repair welding drops to within 55°C.

Embodiment 3

[0050] A casing joint welding process for pipes, the difference from Embodiment 1 is that the gap between the casing 2 and the pipe 1 is 3 mm. The welding process parameters in step S4 are as follows: first layer: welding current 110A, arc voltage 12V, welding speed 8cm / min, argon gas flow rate 10L / min; other layers: welding current 130A, arc voltage 15V, welding speed 6cm / min , Argon gas flow rate 12L / min. S7: First remove the cracked weld metal, and use the set low current welding method to repair the cracks in multiple passes. The welding process parameters of the low current welding method are set as welding current 110A, arc voltage 12V, welding speed 8cm / min, argon The air flow rate is 10L / min. In multi-pass repair welding, the next repair welding is performed when the temperature after the previous repair welding drops to within 60°C.

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Abstract

The invention relates to the technical field of pipeline welding, and discloses a welding process for casing joints of pipelines, which includes the following steps: S1: removing oil stains inside and outside the pipe wall; S2: removing peeling on the inner wall of the casing; S3: connecting the casing to the pipeline Outside the end, the gap between the sleeve and the pipe is 2‑3mm; S4: multi-layer welding is performed on the gap between the pipe and the sleeve to form a multi-layer weld coaxial with the pipe; S5: multi-layer weld After forming, weld the capping layer on the weld seam, and the capping layer covers the weld seam and the end of the pipe; S6: During the arc extinguishing process, the arc crater is filled with welding wire; it prevents the generation of low melting point liquid film and reduces the Welding tensile stress controls the infiltration of harmful substances. Multi-layer welding can effectively attenuate residual tensile stress after welding, slow down cooling rate, prevent thermal cracks, slow arc extinguishing, fill arc craters with welding wire, and further prevent thermal cracks.

Description

technical field [0001] The invention relates to the technical field of pipeline welding, in particular to a welding process for casing joints of pipelines. Background technique [0002] Pipe joint welding is a common process in pipeline welding. In many cases, 1Cr18Ni9Ti austenitic stainless steel is used as the pipe fitting and casing material for pipe joint welding. It has the characteristics of small thermal conductivity and large linear expansion coefficient. produce greater thermal stress. [0003] The above-mentioned existing technical solutions have the following defects: if cracks appear in the welded parts of the pipe joints, there will be dangers of pipe leakage. The reasons for cracks are as follows: incomplete cleaning of impurities before welding, excessive current during welding, and excessive cooling speed. Contents of the invention [0004] In view of the deficiencies in the prior art, one of the purposes of the present invention is to provide a casing jo...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B23K9/028B23K9/235
CPCB23K9/028B23K9/0282B23K9/235
Inventor 冯旭东
Owner 上海江南船舶管业有限公司
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