CN102954996A - Method for determining pipeline recesses through triaxial magnetic leakage internal detection line signal - Google Patents

Abstract

The invention provides a method for determining pipeline recesses through triaxial magnetic leakage internal detection line signals. The method uses four three-dimensional hall sensors to record three magnetic leakage signals with independent axial directions, analyzes component characteristics of magnetic leakage in three directions at pipeline defects through a specialized magnetic leakage data read tool, and determines types of the defects as well as depth, length and width information of the defects. If the following conditions are met, recesses can be determined to exist in the pipeline: (1) an amplitude changing of an axial signal is less than or equal to 5 mt; (2) a radial signal is a bidirectional pulse wave, a height amplitude of the signal is more than or equal to 20 mt and a continuously changed length of the signal is more than 10 mm; and (3) an amplitude changing of a transverse signal is less than or equal to 5 mt. A relationship between the defect sizes and the magnetic leakage signals is that a defect depth d (mm) is in an exponential relationship with the height amplitude h (mt) of the radial signal, that is, d=18.82*e^0.001h. The method is simple and reliable to determine recess signals of the internal detection.

Description

Detection line signal determining method in a kind of canal depression three axle leakage fields

Technical field

The present invention is detection line signal determining method in a kind of canal depression three axle leakage fields.Relate to and measure magnetic variable and piping system technical field.

Background technology

The at present main internal detector that adopts how much is judged in the detection of canal depression, detecting device loads a plurality of mechanical arms, if distortion appears in pipeline, the mechanical arm automatic telescopic, sensor on the mechanical arm sends signal simultaneously, enter data storage system, use the deformation analysis software of specialty to carry out data analysis, can obtain geometry deformation size and position on the pipeline.But the method can only be found the depression greater than 2% caliber, judge the threaten degree of depression in the pipeline actual moving process or have to cave in both at home and abroad and repair the decision criteria Main Basis degree of depth and two indexs of curvature, for the depression less than 2% caliber, in case exist than deep camber, to cause pipeline failure to break, have a strong impact on the safe operation of pipeline, the depression that how to identify less than 2% caliber becomes a technical barrier.

CN101968463A discloses detection line signal recognition method in a kind of spiral pipeline weld seam crack like defect three axle leakage fields; " Non-Destructive Testing " 01 phase in 2011 " based on the pipeline feature identification of three axle leakage field inner detection techniques " discloses the pipeline feature identification based on three axle leakage field inner detection techniques.Following technical characterictic is specifically all disclosed: utilize four three-dimensional Hall elements, the magnetic leakage signal of three discrete axial of record, the leakage field that reads three directions of tool analysis by special magnetic flux leakage data divides measure feature, judge the type of defective and the degree of depth, length, the width of defective, but do not provide the decision criteria of depression.

Summary of the invention

The objective of the invention is to invent a kind of method of utilizing detection line signal characteristic judgement canal depression in the three axle high definition leakage fields.

Detection can only provide the signal characteristic under the axial or tangential single direction in the present common leakage field, but because depression belongs to the body distortion, does not exist in the situation of metal loss, does not substantially have to change at axial or horizontal line signal characteristic.And the radial line signal that detects in the three axle leakage fields is to caving in sensitivity, the generation field signal departs from, thereby depression can be distinguished over metal loss class defective, the technology path that the present invention solves is according to the signal determining principle of three axle leakage field internal detectors to defective, by to the statistics of flaw indication feature and the correspondence of real defect, find out signal characteristic.

Technical scheme of the present invention:

Three axle high definition flux leakage detectors utilize four three-dimensional Hall elements to replace 4 traditional coil pickoffs, can record the magnetic leakage signal (traditional leakage field instrument can only record one or two direction) of three discrete axial, be axial (Axial) of pipeline, radially (Radial), the horizontal leakage field component of (Transverse) three directions, the leakage field that reads three directions in tool analysis defect of pipeline place by special magnetic flux leakage data divides measure feature, can judge the type of defective, and the information such as degree of depth of defective, length, width.

Canal depression is mainly the distortion of body, and the radial line signal that therefore detects in the three axle leakage fields produces and departs from, and radially can produce certain leakage field.If in three axle high definition leakage fields, possess simultaneously following three conditions in the detection signal, think that then there is depression in pipeline:

1) axially signal is substantially unchanged, and namely the signal intensity amplitude is less than or equal to 5mt; Fig. 1 is seen in the performance signal;

2) radial signals is the bidirectional pulse ripple, and the signal height amplitude should be equal to or greater than 20mt, and signal continually varying length is greater than 10mm vertically, Fig. 2 is seen in performance signal;

3) laterally signal is substantially unchanged, and namely the signal intensity amplitude is less than or equal to 5mt; Fig. 1 is seen in the performance signal;

There is following relation between its flaw size size and the magnetic leakage signal:

Depth of defect d (mm) and radial signals height amplitude h (mt) exponent function relation namely satisfy d=18.82*e^0.001h; Fig. 2 is seen in the performance signal;

As from the foregoing, because the detection signal decision method is by certain rule, utilizes the abnormal signal feature that identifies the discovery of three axle high definition leakage field internal detectors to take a decision as to whether canal depression in the present invention, and provided the flaw size determination methods, improve internal detector and identified such defective ability, solve the decision problem of three axle high definition leakage field internal detectors to canal depression, improved the Integrity Management level.Not only internally detection depression signal determining is simple, reliable for this method simultaneously, and is easy to study and application.

Description of drawings

Detect axial signal waveforms in the corresponding three axle high definition leakage fields of real defect on Fig. 1 pipeline

Detect the radial signals oscillogram in the corresponding three axle high definition leakage fields of real defect on Fig. 2 pipeline

Detect horizontal signal waveforms in the corresponding three axle high definition leakage fields of real defect on Fig. 3 pipeline

Embodiment

Embodiment. this example is the industrial field of doing at certain Φ 720mm pipeline.

This example is real defect feature and the interior detection signal of three axle high definition leakage fields on this pipeline, sees Fig. 1-Fig. 3 for details.

It is according to decision method of the present invention, will verify sample after the fault location excision on pipeline.There is real defect at a place on pipeline, in three axle high definition leakage fields, detect, as shown in Figure 1 axially signal waveforms, as shown in Figure 2 radial signals oscillogram, horizontal signal waveforms as shown in Figure 3.This axial signal waveforms and horizontal waveform figure line signal are substantially unchanged, and signal amplitude changes less than 3mt; Radial signals is the bidirectional pulse ripple, and the signal height amplitude is 40mt, and signal vertically continually varying length greater than 10mm.Therefore determine to be canal depression herein, the degree of depth of this depression is d=18.82*e^ (0.001*40)=19.58mm, the depth of defect of actual samples is 20mm, and error is 0.42mm, is in the tolerance interval, has confirmed the reliability of size discrimination model.

The result of actual measurement conforms to actual fully, has also just verified the correctness of the method.

Claims (1)

1. detection line signal determining method in the canal depression three axle leakage fields, it is characterized in that utilizing four three-dimensional Hall elements, the magnetic leakage signal of three discrete axial of record, be pipeline axially, radially, the leakage field component of horizontal three directions, the leakage field that reads three directions in tool analysis defect of pipeline place by special magnetic flux leakage data divides measure feature, judge the type of defective, and the degree of depth of defective, length, width information; If in three axle high definition leakage fields, possess simultaneously following three conditions in the detection signal, think that then there is depression in pipeline:

1) axially signal is substantially unchanged, and namely the signal intensity amplitude is less than or equal to 5mt;

2) radial signals is the bidirectional pulse ripple, and the signal height amplitude should be equal to or greater than 20mt, and signal vertically continually varying length greater than 10mm;

3) laterally signal is substantially unchanged, and namely the signal intensity amplitude is less than or equal to 5mt;

There is following relation between its flaw size size and the magnetic leakage signal:

Depth of defect d and radial signals height amplitude h exponent function relation namely satisfy d=18.82*e^0.001h.

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