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A magnetic-structure coupling method detecting weld seam crack expansion of in-service pipelines through a magnetic flux leakage process

A welding seam crack and crack propagation technology, applied in the direction of material magnetic variable, etc., to achieve the effect of easy fracture and avoid the occurrence of malignant accidents

Active Publication Date: 2018-05-15
NORTHEAST GASOLINEEUM UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, through domestic and foreign literature searches, no related technologies have been found for the magnetic-structural coupling method of weld crack propagation in oil and gas pipelines. This invention will fill the technical gap in this field

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  • A magnetic-structure coupling method detecting weld seam crack expansion of in-service pipelines through a magnetic flux leakage process
  • A magnetic-structure coupling method detecting weld seam crack expansion of in-service pipelines through a magnetic flux leakage process
  • A magnetic-structure coupling method detecting weld seam crack expansion of in-service pipelines through a magnetic flux leakage process

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Embodiment Construction

[0072] Below in conjunction with accompanying drawing, the present invention will be further described:

[0073] combine figure 1 As shown, the microcracks are distributed in the center of the weld bead ( Figure 8 As an example, the magnetic-structural coupling method of this magnetic flux leakage method to detect weld cracks in in-service pipelines is as follows:

[0074] Step 1. Based on ANSYS finite element software, perform parameterized assignment, including geometric dimensions, material parameters, load parameters and other parameters.

[0075] (1) Assign values ​​to the geometric parameters of pipes, welds, microcracks, magnetized structures, and surrounding air.

[0076] a. The geometric parameters of the two-dimensional pipeline include the inner diameter of the pipeline D i = 400mm, outer diameter D o = 416mm;

[0077] b. The geometric parameters of the weld include the weld width B 1 =18mm, excess height H 1 =2mm;

[0078] c. The geometric parameters ...

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Abstract

The invention relates to a magnetic-structure coupling method detecting weld seam crack expansion of in-service pipelines through a magnetic flux leakage process. The method includes 1) performing parameterization assignment based on ANSYS finite element software; 2) selecting a structural stress analysis unit type, performing pipeline weld seam modeling and applying displacement and load boundaryconditions; 3) constructing an initial micro crack based on a VCCT technique, and calculating crack expansion according to an energy release rate rule; 4) according to an open distance and an expansion length in a crack expansion process, reconstructing an air grid at the crack position; 5) according to structure characteristics of a pipeline weld seam, building an external-inspection magnetization structure model including permanent magnets, an armature and pole shoes at the pipeline weld seam; 6) designing an arc path above the pipeline weld seam, extracting a magnetic-structure coupling calculation result, analyzing the position and intensity of a magnetic flux leakage, and evaluating the crack expansion process; 7) repeating step 3) to the step 6), and performing calculation and analysis repeatedly until the pipeline is broken. The degree of weld seam damage of pipelines can be determined by the method.

Description

technical field [0001] The invention relates to an in-service detection method for pipeline welds in the technical field of oil and gas gathering and transportation engineering, in particular to a magnetic-structure coupling method for detecting the expansion of weld cracks in in-service pipelines by magnetic flux leakage. Background technique [0002] In the long-term operation of oil and gas pipelines, major accidents such as corrosion, perforation, cracking, and seal failure may occur, causing major fires or explosions caused by oil leakage, posing a serious threat to the safety of people's lives and property and the ecological environment. Common damage failure modes tend to occur in stress concentration areas, especially on the weld bead of oil and gas pipeline weld areas and their heat-affected zones. The stress concentration areas are prone to stress corrosion cracking and induced cracking under the joint action of pressure and media. Many catastrophic accidents are c...

Claims

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Application Information

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IPC IPC(8): G01N27/83
CPCG01N27/83
Inventor 崔巍张强徐晔张静李健奇宋微刘佳鹏张云忠
Owner NORTHEAST GASOLINEEUM UNIV