Fractal dimension representation method for expansion trend of corrosion fatigue crack of gas pipeline

A fractal dimension and crack propagation technology, applied in the direction of analyzing materials, measuring devices, instruments, etc., can solve the problems of uncertainty, time-consuming and labor-intensive, and achieve the effect of cost reduction

Inactive Publication Date: 2017-08-22
XIAN UNIV OF POSTS & TELECOMM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In order to obtain reliable results, the Paris method requires a large number of samples for long-term measurement, which is very time-consuming and labor-intensive
As mentioned earlier, due to the influence of the environment, some measured parameter values ​​have certain uncertainties

Method used

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  • Fractal dimension representation method for expansion trend of corrosion fatigue crack of gas pipeline
  • Fractal dimension representation method for expansion trend of corrosion fatigue crack of gas pipeline
  • Fractal dimension representation method for expansion trend of corrosion fatigue crack of gas pipeline

Examples

Experimental program
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Effect test

Embodiment 1

[0064] A fractal dimension characterization method for corrosion fatigue crack growth tendency of gas pipeline, comprising the following steps:

[0065] 1. Cut the pipe and make a CT sample, followed by surface cleaning and drying

[0066] 1) Cut the pipe: press figure 1 As shown, the arc-shaped pipe was cut. The test material was taken from a certain pipe in Puguang Gas Field. The design pressure was 11MPa and the wall thickness was 17.5mm. That is, the circumferential direction; R indicates that the crack expands along the wall thickness. Since the pipe wall is very thin, it is impossible to cut the sample according to the CR orientation, so the sample can only be cut from the pipe according to the CL orientation. L is the direction of crack propagation, according to CL Orientation intercepted 3 samples of base metal;

[0067] 2) Preparation of CT samples: CT samples were made according to GB / T 6398-2000 standard. After the above-mentioned arc-shaped samples were removed, ...

Embodiment 2

[0089] A fractal dimension characterization method for corrosion fatigue crack growth tendency of gas pipelines, the main steps of which are as follows:

[0090] Step 1, cut the pipe and make a CT sample, followed by surface cleaning and drying;

[0091] (1) Cut and prepare CT sample: press figure 1 Cut the curved tube as shown, and then make the curved tube into a CT sample (such as figure 2 shown);

[0092] (2) Prefabricated fatigue cracks: the precrack load ratio is 0.1, the maximum load is 10kN, and the length of the prefabricated fatigue cracks is about 1.5-2mm;

[0093] (3) Cleaning: firstly carry out rust removal on the surface of the sample, and the formula of the rust removal solution is as follows:

[0094] formula weight percentage Hydrochloric acid (mass concentration 15%) 55％ Hexamethylenetetramine 10％ water 35％

[0095] Soak the sample in the derusting solution to ensure that the surface of the CT sample is fully exposed to ...

Embodiment 3

[0113] A fractal dimension characterization method for corrosion fatigue crack growth tendency of gas pipelines, the main steps of which are as follows:

[0114] Step 1, cut the pipe and make a CT sample, followed by surface cleaning and drying.

[0115] 1) Cut and prepare CT sample: press figure 1 Cut the curved tube as shown, and then make the curved tube into a CT sample (such as figure 2 shown).

[0116] 2) Pre-fabricated fatigue cracks: the pre-crack load ratio is 0.1, and the maximum load is 10kN. The length of the prefabricated fatigue crack is about 1.5-2mm.

[0117] 3) Cleaning: firstly carry out rust removal on the surface of the sample, the formula of the rust removal solution is as follows:

[0118] formula weight percentage Hydrochloric acid (mass concentration 15%) 55％ Hexamethylenetetramine 10％ water 35％

[0119] Soak the sample in the derusting solution to ensure that the surface of the CT sample is fully exposed to the d...

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Abstract

The invention discloses a fractal dimension representation method for an expansion trend of a corrosion fatigue crack of a gas pipeline. The method comprises the steps of firstly cutting an L360 pipe wall material and preparing a CT sample; secondly, carrying out pre-fatigue noise testing and fractal dimension calculation on the pipe crack; thirdly, carrying out corrosion fatigue testing on the CT sample on a fatigue machine; finally carrying out noise testing on the corrosion fatigue crack and calculating a fractal dimension, wherein the expansion trend of the fatigue crack of the gas pipeline can be reflected according to the fractal dimension change of the crack noise calculated before and after the fatigue. Low-frequency noise testing and calculation are carried out on the sample, and the sample is not destroyed by the behavior, so that the method is a nondestructive testing means, and furthermore, the test can be carried out on most of metal pipes, and has relatively wide applicability.

Description

technical field [0001] The invention relates to a fractal dimension characterization method for corrosion fatigue crack propagation tendency of a gas transmission pipeline. It is specifically related to the low-frequency noise fractal dimension characterization method of L360 gas pipeline corrosion fatigue crack growth. This method first measures the low-frequency noise data of pipeline cracks before and after corrosion fatigue and calculates its fractal dimension value, and then reflects the expansion trend of fatigue cracks in oil and gas pipelines according to the calculated fractal dimension changes. Background technique [0002] my country's energy reserves are unevenly distributed geographically. The Tarim Basin, Qaidam Basin, Shaanxi-Gansu-Ningxia and Sichuan Basins in the western region contain 26 trillion cubic meters of natural gas resources and rich oil resources, accounting for about 87% of the country's onshore natural gas resources. Due to the rapid developme...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/56
CPCG01N3/56G01N2203/0066G01N2203/0073G01N2203/0274
Inventor 谢端
Owner XIAN UNIV OF POSTS & TELECOMM
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