Method for nondestructive examination of oxide thickness distribution in stainless steel tubes

A stainless steel tube, non-destructive testing technology, applied in the direction of electric/magnetic thickness measurement, electromagnetic measurement device, material magnetic variable, etc., can solve the problems of incompatibility, inability to effectively detect the boundary condition of oxide scale, boundary insensitivity, etc.

Inactive Publication Date: 2009-11-25
林俊明
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

This method can be used to detect whether there are internal oxides in the austenitic stainless steel pipe, and, according to the proportional relationship between the stray magnetic field strength and the amount of magnetic substances in the pipe, it can also reflect the amount of internal oxides to a certain extent. However, There are two types of scale in the elbow section of the stainless steel pipe, one is the primary scale, which is closely attached to the inner wall of the stainless steel tube, and the other is the drop-type scale, which is formed from the primary scale In the parts accumulated after cracking and peeling, the contact between the dropped oxide scales is in a loose state, and there are gaps between them, tha

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  • Method for nondestructive examination of oxide thickness distribution in stainless steel tubes

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Embodiment 1

[0030] Embodiment one, see figure 1 As shown, a method for non-destructive testing of oxide scale thickness distribution in stainless steel pipes of the present invention comprises the following steps:

[0031]a. The eddy current sensor 1 is attached to a position on the outer wall of the elbow section (i.e. the U-shaped pipe section) of the stainless steel pipe 10; the eddy current sensor 1 is mounted on an adaptive probe bracket 2, and the adaptive probe bracket 2 includes The two arms are the first arm 21 and the second arm 22, the first arm 21 and the second arm 22 are pivotally connected and connected by a spring, so that the first arm 21 and the first arm 22 can be opened to each other to form any angle within 180 degrees , to adapt to different pipe diameters of stainless steel pipes; when the eddy current sensor 1 is installed on the self-adaptive probe bracket, it can be connected by thread, so that the eddy current sensor 1 can be adjusted up and down, so that the ed...

Embodiment 2

[0038] Embodiment 2, a method for non-destructive testing of oxide scale thickness distribution in stainless steel pipes according to the present invention, comprising the following steps:

[0039] A. Wrap the multi-channel eddy current sensors arranged in a linear array around the stainless steel pipe wall in a 360° manner around a circle of the wall of the elbow section of the stainless steel pipe (i.e. the U-shaped pipe section);

[0040] B. The eddy current sensors of each channel are respectively excited by the preset multi-frequency signal sent by the arbitrary waveform generator in the way of time-sharing excitation, and the multi-frequency excitation signal passes through the pipe wall of the stainless steel pipe to generate eddy current in the oxide skin;

[0041] C. The eddy current sensor corresponding to each channel picks up the eddy current induction signal of the oxide skin by the respective eddy current sensor, and the eddy current induction signal output by eac...

Embodiment 3

[0045] Embodiment 3, a method for non-destructive testing of oxide skin thickness distribution in stainless steel pipes according to the present invention, comprising:

[0046] Wrap the flexible multi-channel eddy current sensors arranged in an area array outside the wall of the bent pipe section (i.e. U-shaped pipe section) of the stainless steel pipe;

[0047] The eddy current sensors of each channel are respectively excited by the preset multi-frequency signal from the arbitrary waveform generator by the method of time-sharing excitation, and the multi-frequency excitation signal passes through the pipe wall of the stainless steel pipe to generate eddy current in the oxide skin;

[0048] The eddy current sensor corresponding to each channel picks up the eddy current sensor signal on the oxide scale, and the eddy current sensor signal output by each eddy current sensor is amplified, phase-sensitive detection, and frequency-mixed to process the interference signal and then sen...

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Abstract

The invention discloses a method for nondestructive examination of oxide thickness distribution in stainless steel tubes, vortex flow transducer is sticked on external wall of bend section in stainless steel tubes, motivated by a multi-frequency signal, vortex flow sensing signal is obtained by the vortex flow transducer, the signal is processed by a computer processing system into data in correspondence position corresponding to oxide thickness of bend section in stainless steel tubes after signal amplification, phase sensitive detection and frequency mixing of interference signals, whole perisporium of the stainless tube is detected by surrounding, a plurality of data in a plurality of positions correspondinig to oxide thickness of bend section in stainless steel tube to be tested is obtained, the computer processing system proceeds imaging treatment according to data of oxide thickness corresponding to stainless steel tubes, images corresponding to stainless steel tubes for mapping oxide vortex flow sensing signals are obtained; and then a pseudo-three-dimensional image corresponding to shape of stainless steel tube is obtained, and oxide distribution conditioin inside the stainless steel is displayed.

Description

technical field [0001] The invention relates to a non-destructive testing method, in particular to a method for non-destructive testing of the oxide skin thickness distribution in a stainless steel tube. Background technique [0002] Non-destructive testing NDT (nondestructive test) is a detection method that does not damage or affect its future performance or use on materials or workpieces. By using NDT, defects existing in the interior and surface of materials or workpieces can be found, and workpieces can be measured. It can determine the internal composition, structure, physical properties and state of materials or workpieces. Non-destructive testing technology has been widely used in various industrial fields, such as manufacturing, aerospace, petrochemical and other fields. [0003] Stainless steel pipes are commonly used as heat exchanger pipes in power stations. During long-term use, the inner walls of the pipes are prone to oxide scales. Oxide skin is a layer of s...

Claims

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Application Information

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IPC IPC(8): G01N27/90G01B7/06
Inventor 林俊明
Owner 林俊明
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