Method and device for testing environmental fracture toughness of petroleum pipe

A technology for oil pipes and fracture toughness, which is applied in the direction of applying stable tension/pressure to test the strength of materials, etc. It can solve the problems of large dispersion of experimental results, complex sample structure, and difficult processing of prefabricated cracks, and achieve reliable experimental methods. Effect

Inactive Publication Date: 2013-06-19
SOUTHWEST PETROLEUM UNIV
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Problems solved by technology

[0004] (A) The structure of the DCB sample is complex, the processing of prefabricated cracks is difficult, the dimensional accuracy is not easy to control, and the size effect of the sample seriously affects the experimental results;
[0005] (B) The experiment uses a wedge to load the sample, the accuracy and parallelism of the loading stress are poor, and the experimental results are highly discrete;
[0006] (C) The sample with double cantilever beam structure is greatly affected by the plasticity of the metal material when it is split, and the load when the crack starts to expand cannot be accur

Method used

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  • Method and device for testing environmental fracture toughness of petroleum pipe
  • Method and device for testing environmental fracture toughness of petroleum pipe
  • Method and device for testing environmental fracture toughness of petroleum pipe

Examples

Experimental program
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Example Embodiment

[0037] Example 1

[0038] Use petroleum pipe A to process the sample as required, determine the corrosive medium and the load stress according to the service conditions, the relationship curve between the load deflection and the stress is as follows image 3 , The detailed loading data is shown in Table 1.

[0039] After corrosion for 168h, it was found that the impact toughness of the oil pipe A was significantly lower than the original state after the corrosion test, the decrease was 14.8%, and the fracture toughness decreased by 48.8%, indicating that the oil pipe A was at a temperature of 60℃, a total pressure of 10MPa, and H 2 S and CO 2 The partial pressures are respectively 1MPa and 1.5MPa, and the toughness and impact resistance are reduced to a certain extent after 168h under the condition of loading 80% nominal yield stress. There is a certain risk in this corrosive environment. The detailed results are shown in Table 2. Figure 4 .

Example Embodiment

[0040] Example 2

[0041] Using the present invention to test the fracture toughness of petroleum pipe B environment, the experimental condition temperature is 60℃, total pressure is 10MPa, H 2 S and CO 2 The partial pressures were 1MPa and 1.5MPa, and the experiment was carried out for 14 days under the condition of 80% nominal yield stress. The experimental data results are shown in Table 3. After the corrosion experiment, the impact performance and fracture toughness of petroleum pipe B were reduced by 90.5% and 93.5% respectively compared with the original state. , Indicating that the oil pipe B has poor resistance to stress corrosion cracking in this environment, cracks initiation and rapid growth, so that the toughness and impact resistance of the oil pipe B are greatly attenuated, and the possibility of environmental fracture is great, and it is not suitable for this environment.

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Abstract

The invention discloses a method and a device for testing the environmental fracture toughness of a petroleum pipe. The method comprises the following steps of: detecting the size of the fracture toughness of the petroleum pipe under the service environment, processing the petroleum pipe into a sample, determining the experimental temperature, pressure and gas-liquid phase corrosive medium according to the service working condition of the pipe, loading the sample by the device for testing the environmental fracture toughness of the petroleum pipe, calculating the fracture toughness according to the load size and the crack expansion length after experiment, and obtaining stress-corrosion-cracking resistance, notch sensitivity and the action mechanism of the metal material in the service environment. The method and the device disclosed by the invention has the advantages that the size of the fracture toughness of the metal material of the petroleum pipe in any load and corrosion environment can be determined, the impact-toughness damage degree of the metal material in the service environment can be detected, so that the preference of the petroleum pipe is carried out and the experimental base is provided for designing the strength of the petroleum pipe.

Description

technical field [0001] The invention relates to a method and device for testing the environmental fracture toughness of petroleum pipes, more specifically, it relates to a method for testing the environmental fracture toughness of petroleum pipes, and also relates to an experimental device for testing the fracture toughness using the method. Background technique [0002] In the petroleum industry, in order to avoid unforeseen accidents and disasters such as pipe cracking, performance attenuation, and intergranular fracture due to stress corrosion, it is necessary to carry out environmental fracture evaluation experiments on petroleum pipes. The applicability and reliability in the research and evaluation. At present, the method of evaluating the environmental fracture of metal materials at home and abroad is mainly the constant load stress corrosion test method, that is, the A method experiment is carried out by using the stress ring under normal temperature and pressure, wh...

Claims

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Application Information

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IPC IPC(8): G01N3/08
Inventor 曾德智侯铎张智施太和任建邓文良
Owner SOUTHWEST PETROLEUM UNIV
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