CN101408625A - Method for detecting underground steel pipe corrosion condition by ground artificial magnetization - Google Patents
Method for detecting underground steel pipe corrosion condition by ground artificial magnetization Download PDFInfo
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Abstract
The invention relates to a method for detecting the corrosion condition of an underground steel pipe. The method for detecting the corrosion condition of the underground steel pipe by ground artificial magnetization is characterized by comprising the following steps: (1) a reference point is chosen at the ground of a site without the magnetic field influence of steel objects, a magnetometer is adopted to respectively measure a magnetic field vertical component value when a magnetic field emission device provides power supply (the magnetic field emission device emits magnetic fields to the surrounding space) and a magnetic field vertical component value when the magnetic field emission device does not provide power supply, and an artificial magnetic field vertical component value of the reference point is obtained based on the difference of the two values; (2) the measurement same as that in the step 1 is performed on a measurement point arranged on the ground above the underground steel pipe to obtain an artificial magnetic field vertical component value of the measurement point; (3) the artificial magnetic field vertical component value of the measurement point is subtract from the artificial magnetic field vertical component value of the reference point to obtain a magnetic field vertical component value generated at the measurement point under the artificial magnetic field magnetization of the underground steel pipe; and (4) that whether the underground steel pipe is corroded and the corrosion degree are determined according to the size of the magnetic field vertical component values of various measurement points; the smaller the magnetic field numerical value is, the more severe the corrosion is. The method has the advantages of low cost and wide scope of applicable pipe diameters, and can effectively detect the corrosion condition of the underground steel pipes.
Description
Technical field
The present invention relates to the detection method of underground steel pipe corrosion condition.
Background technology
Pipeline transportation is one of China's five big transportatioies industry, and it is widely used in industries such as oil gas, chemical industry, feedwater and heating, and extremely important status is arranged in national economy.Pipeline transportation is used steel pipe always.The steel pipe of imbedding in the ground is underground because of bury underground throughout the year, and multiple factors such as its surrounding environment and tube fluid can cause corrosive pipeline.The steel pipe of inflammable and explosive fluids such as transfer oil, rock gas, coal gas, because of accidents such as corrosion failure runs, emits, leakage also often take place, not only influence normally carrying out of production work, and pollute the environment, even set off an explosion and fire, cause heavy losses for the country and people's property and life.Therefore, the corrosion condition to underground steel pipe detects and monitors.Has crucial meaning.
Bury and be usually expressed as the tube wall attenuation of pipeline after the ground steel pipe corrodes, or pit and pit occur.At present, the method that detects underground steel pipe corrosion condition both at home and abroad mostly is to carry out in pipe.This class detection technique has leakage flux method, eddy-current method, laser method, supercritical ultrasonics technology and communications Act of 1934 etc.Wherein laser detection method and TV detection method need just can draw pipeline corrosion data effectively accurately with other method cooperation.Though eddy-current method goes for multiple black and non-ferrous metal pipeline, eddy current to the penetration power of ferromagnetic material too a little less than, can only be used for detecting the surface corrosion situation of steel pipe.In addition, because the testing result of eddy-current method and the conductivity of detected metal have relation, also require tested steel pipe to keep constant temperature in order to improve measuring accuracy.So external now use corrosive pipeline detection method more widely is leakage flux method and supercritical ultrasonics technology.
Domesticly introduce ultrasonic Detection Method and leakage flux detection method instrument and equipment is counted cover, and succeeded in developing the leakage flux detector voluntarily.Because this class methods instrument and equipment costliness (import instrument equipment whenever is enclosed within more than 1,000,000 dollars), detect the cost height (for example somewhere φ 720mm ultrasound examination only usage charges just up to more than 130 ten thousand yuan/70km, only use the battery expense just reach 300,000 yuan/70km), the height of testing cost is that general unit is difficult to bear.Because a kind of model of detector only is suitable for a kind of caliber in the pipe, and oil field and petroleum chemical enterprise's gathering line specification are varied, can not spend the detecting instrument that a huge sum of money removes to purchase all size.In addition, the following caliber of φ 273mm does not also have this type of detector, thereby can't detect with these class methods the pipeline of the following size of φ 273mm that accounts for the suitable vast scale of gathering line.Should be noted also that when pipeline corrosion detect to be implemented to influence production, runs into some situation (for example pipeline turns round) even can't move.Above factor has restricted the development that domestic pipeline corrosion detects.
At present, domestic many detection units can only measure its corrosion condition at the steel pipe place that suspection is corroded with supercritical ultrasonics technology on the basis of anticorrosive coat detection and pipe corrosion environmental assessment, must excavate and peel off anticorrosive coat for this reason, again instrument are close to steel pipe and measure.Therefore, the method and the instrument and equipment of the economic and practical underground pipe corrosion situation of detection of research are the task of top priority.
Summary of the invention
The object of the present invention is to provide a kind of ground artificial magnetization to detect the method for underground steel pipe corrosion condition, this method testing cost is cheap, be suitable for the caliber scope big, can effectively detect underground steel pipe corrosion condition.
For achieving the above object, technical scheme of the present invention is: ground artificial magnetization detects the method for underground steel pipe corrosion condition, it is characterized in that it comprises the steps:
1) selects a basic point on ground, no iron and steel thing influence of magnetic field place, the emission of magnetic field device is settled on the ground, survey the magnetic field vertical component value that when the emission of magnetic field device is not powered, (does not produce under the situation of artificial magnetic field) with the magnetometer of surveying vertical magnetic field, magnetic field vertical component value when obtaining basic point and not powering;
To emission of magnetic field device power supply, the emission of magnetic field device is spatial emission magnetic field towards periphery then, makes magnetic field with the same depth location of underground steel pipe depth value to be detected greater than 0.2 * 10
-4Tesla (T) (contains 0.2 * 10
-4Tesla), surveys the magnetic field vertical component value of when the emission of magnetic field device is powered (producing under the situation of artificial magnetic field), magnetic field vertical component value when obtaining the basic point power supply with the magnetometer of surveying vertical magnetic field;
Magnetic field vertical component value when magnetic field vertical component value subtracts basic point and do not power when powering with basic point, the gained difference is basic point artificial magnetic field vertical component value;
2) the ground configuration measuring point directly over underground steel pipe to be detected, the emission of magnetic field device is placed in ground measuring point place, at the measuring point place earlier with the magnetic field vertical component value of magnetometer survey when the emission of magnetic field device is not powered of surveying vertical magnetic field, magnetic field vertical component value when obtaining measuring point and not powering;
To the power supply of emission of magnetic field device, the emission of magnetic field device is the spatial emission magnetic field identical with step 1) towards periphery then, with the magnetic field vertical component value of magnetometer survey when the emission of magnetic field device is powered of surveying vertical magnetic field, magnetic field vertical component value when obtaining the measuring point power supply;
Magnetic field vertical component value when magnetic field vertical component value subtracts measuring point and do not power when powering with measuring point, the gained difference is measuring point place artificial magnetic field vertical component value;
3) measuring point artificial magnetic field vertical component value subtracts the magnetic field vertical component value that basic point artificial magnetic field vertical component value obtains measuring point place underground steel pipe (or claiming underground steel pipe) generation under the artificial magnetic field magnetization;
4) size of the magnetic field vertical component value that produces down according to the above-mentioned artificial magnetic field magnetization of each measuring point determine whether underground steel pipe has been corroded and the degree that is corroded (numerical value is more or less the same more greatly and each other on the underground steel pipe section that is not corroded, on the underground steel pipe section that has been corroded then numerical value obviously reduce); The magnetic field vertical component value numerical value that produces under this artificial magnetic field magnetisation is more little, illustrate be corroded serious more.
The magnetic field vertical component value that artificial magnetic field magnetization produces down on the underground steel pipe section that is not corroded is divided by the thickness of pipe in millimeter, the magnetic field numerical value that should reduce when approximating 1 millimeter of the thickness that on average is corroded (equal rotten thickness) greatly.It generally is to be a hot spot (measuring point) more than the scope with 1 meter that the corrosion of steel pipe at present detects.Corrosion depth is a heavy corrosion greater than 4 millimeters; Corrosion depth is that moderate is corroded the 2-4 millimeter; Corrosion depth less than 2 millimeters be mild corrosion.According to maintenance requirement, the overhaul in time of heavy corrosion point.
One of described emission of magnetic field device is the twin coil device, and it comprises bracing frame 1, big coil 2, pin 3, small coil 4, second binding post 6; Bracing frame 1 is made up of big toroidal frame, little toroidal frame, connecting link, little toroidal frame is positioned at big toroidal frame, and little toroidal frame and big toroidal frame concentric, little toroidal frame is fixedlyed connected with big toroidal frame by at least 3 connecting links, is respectively equipped with ring groove on little toroidal frame, the big toroidal frame; Be wound with big coil 2 in the ring groove on the big toroidal frame, the two ends of big coil 2 link to each other with first binding post, second binding post 6 respectively; Be wound with small coil 4 in the ring groove on the little toroidal frame, the two ends of small coil 4 link to each other with the 3rd binding post, the 4th binding post respectively; Second binding post links to each other with the 3rd binding post or the 4th binding post, makes big coil stream direction opposite (clockwise direction, another is counter-clockwise direction then) with electric current in the small coil; First binding post and the 3rd binding post or the 4th binding post are respectively by lead, switch link to each other with the both positive and negative polarity of power supply (the 3rd binding post or the 4th binding post for do not link to each other with second binding post); The center pit internal fixation of little toroidal frame has the sensor of the magnetometer of surveying vertical magnetic field; Big coil 2 and small coil 4 are at grade; Be fixedly connected with that the 3-5 root is collapsible, the pin of adjustable length 3 end of big toroidal frame.
Two of described emission of magnetic field device is the floor file loop line.
The invention has the beneficial effects as follows: adopt said method, testing cost cheap (method is easy, equipment price is cheap), be suitable for caliber scope big (being applicable to the steel pipe of all size), can effectively detect underground steel pipe corrosion condition.It can detect the heavy corrosion section of underground steel pipe, moderate corrosion section, even mild corrosion section.And applicable to cast-iron pipe.
Description of drawings
Fig. 1 is the synoptic diagram of ring current field;
Fig. 2 is the synoptic diagram that calculates line current section magnetic field;
Fig. 3 is the structural representation of twin coil device;
Fig. 4 produces the corrosion detection arrangement figure that underground steel pipe is carried out in magnetic field with the floor file loop line;
Among the figure: 1-bracing frame, the big coil of 2-, 3-pin, 4-small coil, the center pit of the little toroidal frame of 5-(the sensor riding position of magnetometer), 6-second binding post, 7-floor file loop line, 8-survey line, the ground projection line of 9-underground steel pipe.
Among Fig. 1: dl is the line element of circular current, and dB is the magnetic field that line element dl produces, x
oy
oZ is three coordinates of rectangular coordinate system, and O is the initial point of rectangular coordinate system, and r is the distance of line circle to measuring point, and θ is the angle on r and circular current plane.
Embodiment
For a better understanding of the present invention, further illustrate content of the present invention, but content of the present invention not only is confined to the following examples below in conjunction with embodiment.
Ultimate principle of the present invention: the material base that artificial magnetizing method detects underground steel pipe (or claiming steel pipe) corrosion condition is that steel pipe has extremely strong magnetic, and the back magnetic forfeiture that is corroded.When steel pipe applies artificial magnetic field, steel pipe is not corroded and partly understands space generation magnetic field around under its magnetization, the distribution of part in artificial magnetic field that be not corroded of its intensity size and the distribute intensity that is decided by artificial magnetic field and steel pipe, thereby also closely related with the distribution of part in artificial magnetic field that be corroded, thereby the size in the magnetic field that can produce under artificial magnetization according to steel pipe is determined the degree that is corroded of steel pipe and the distribution situation of the part that is corroded with distributing.
As everyone knows, have magnetic field on the earth, be called the terrestrial magnetic field.Because the existence of terrestrial magnetic field, underground steel pipe can produce magnetic field around under its magnetization, and in addition, steel pipe often has remanent magnetization, also can produce magnetic field around.When underground steel pipe applies artificial magnetic field, around the steel pipe except that the magnetic field that the remanent magnetization of magnetic field under the magnetization of terrestrial magnetic field of the artificial magnetic field that applies, terrestrial magnetic field, steel pipe, steel pipe produces, the magnetic field that also has steel pipe under the artificial magnetic field magnetization, to produce.Because above-mentioned each magnetic field is vector, obtain the artificial magnetization magnetic field of steel pipe by magnetic survey onlyly, the energy measurement resultant field must not measured the component of resultant field in Cartesian coordinates.For convenient and effectively for the purpose of, adopt the means of measuring the magnetic field vertical component and adopt relative measurement.Like this, just can obtain the magnetic field vertical component that buried steel pipe produces by three steps of the present invention under the artificial magnetic field magnetization.
The artificial magnetic field that applies to underground steel pipe can be that alive coil produces, and also can be that alive floor file loop line produces, and it should be more or less the same with geomagnetic field intensity in steel pipe place intensity, and (too conference makes the equipment heaviness, influences efficient; The too little measuring accuracy that then influences), its intensity should be greater than 0.2 * 10
-4Tesla (T) just can obtain good result.
In Gauss's cgs unit system, the magnetic field formula of circular current during galvanization (Fig. 1) is (Purcell, 1979, electromagnetics " study course of Berkeley physics " second volume, P.251 a, Science Press)
In the formula, I-supply current intensity, the c-light velocity (c=2.998 * 10
10Cm/sec), the b-coil radius, any is to the distance in the center of circle on the z-axle.
For the number of turn is the multiturn circular coil of n, and (1) formula becomes
The magnetic field of square or rectangular loop can be tried to achieve according to the formula of limited long-line current.As Fig. 2, galvanization is that the magnetic field formula of line current section A, the B of I is (Zhang Qiuguang, 1983, field theory " first volume ", P.248, Geology Publishing House)
In the formula, the c-light velocity (c=2.998 * 10
10Cm/sec), I, ρ, θ
1, θ
2As shown in Figure 2,
It is a basic vector of cylindrical coordinates.In order to make underground steel pipe place that the artificial magnetic field suitable with geomagnetic field intensity be arranged, the floor file loop line also must be a multiturn.
The invention provides the twin coil device that can produce artificial magnetic field behind the galvanization around, as shown in Figure 3, it comprises bracing frame 1, big coil 2, pin 3, small coil 4, second binding post 6; Bracing frame 1 is made up of big toroidal frame, little toroidal frame, connecting link, little toroidal frame is positioned at big toroidal frame, and little toroidal frame and big toroidal frame concentric, little toroidal frame is fixedlyed connected (being 6 among Fig. 3) with big toroidal frame by at least 3 connecting links, is respectively equipped with ring groove on little toroidal frame, the big toroidal frame; Be wound with big coil 2 in the ring groove on the big toroidal frame, the two ends of big coil 2 link to each other with first binding post, second binding post 6 respectively; Be wound with small coil 4 in the ring groove on the little toroidal frame, the two ends of small coil 4 link to each other with the 3rd binding post, the 4th binding post respectively; Second binding post links to each other with the 3rd binding post or the 4th binding post, makes big coil stream direction opposite (clockwise direction, another is counter-clockwise direction then) with electric current in the small coil; First binding post and the 3rd binding post or the 4th binding post are respectively by lead, switch link to each other with the both positive and negative polarity of power supply (the 3rd binding post or the 4th binding post for do not link to each other with second binding post); Center pit 5 internal fixation of little toroidal frame have the sensor of the magnetometer of surveying vertical magnetic field; Big coil 2 and small coil 4 are at grade; Be fixedly connected with that the 3-5 root is collapsible, the pin of adjustable length 3 (among Fig. 3 being 3) end of big toroidal frame.The main effect of big coil is to produce enough artificial magnetic fields at underground steel pipe place, and the small coil of the inside then is to be used for compensating big coil in the magnetic field at the Magnetic Sensor place that is positioned at the center.
Because the twin coil device is lighter, it is higher to carry out the underground steel pipe corrosion detection efficiency with twin coil device emission artificial magnetic field, so be suitable for generally investigating.During measurement the twin coil device be centered close to measuring point on the ground projection line (steel pipe ground projected position just can easily be measured with pipe and cable detector) that is arranged in underground steel pipe directly over, the measuring point spacing can be decided to be 5-10 rice.In the noticeable corrosion section that generaI investigation is found, available floor file loop line produces the corrosion detection that underground steel pipe is carried out in magnetic field; Floor file loop line size generally can be 15 meters * 15 meters, and is also changeable, also apart from shape, as required and condition (for example power supply, cable etc.) decision.The floor file loop line should be symmetrical in the surface projection line of pipeline, two opposite side and pipeline surface projection line parallel, survey line 8 by floor file loop line 7 mid point and with the ground projection line 9 vertical (as shown in Figure 4) of underground steel pipe.On survey line, measure (for example 20 cm point distance) along survey line with closeer some distance with magnetometer.Because be approximately uniform field in the magnetic field at steel pipe place, below in the middle, can obtain the sectional drawing that corrodes part and corrosion part of square steel tube under the survey line by inverting according to the steel pipe artificial magnetization magnetic field data that measures than big floor file loop line.
Carried out the detection of actual steel pipe in Zhongyuan Oil Field branch office of China Petrochemical Industry and two places, Daliang City:
One, the experimental demonstration of method of the present invention (carrying out the detection of actual steel pipe) in Zhongyuan Oil Field branch office of China Petrochemical Industry:
With the magnetometer (its sensor is placed in directly over the hub of a spool) of the survey vertical magnetic field of twin coil device and space center of Chinese Academy of Sciences solar system detecting chamber, formed the artificial magnetic field method detecting instrument of test usefulness.Under the technical monitoring center support of Zhongyuan Oil Field branch office of China Petrochemical Industry, test.
Select the new pipe crimping of the φ 377mm * 7mm of the new weldless steel tube of φ 273mm * 10mm of one 12 meters long and one 9 meters long (round steel pipe that curls and be welded into by steel plate), the equal horizontal setting of weldless steel tube and pipe crimping, between pipe about 7 meters apart.Weldless steel tube, pipe crimping middle part are decided to be measuring point apart from its 1/3rd pipe range places, two ends.Basic point is selected in apart from these two steel pipes (no iron and steel thing influence of magnetic field place) at a distance.
During measurement, 1.36 meters in the twin coil device that all dried up safety in the bottom of weldless steel tube or pipe crimping is put (measuring respectively).When measuring point is measured the hub of a spool of twin coil device be positioned at weldless steel tube or pipe crimping measuring point directly over (measure respectively).
With two 12 volts of accumulator jars as power supply (having only two accumulator jars), its supply voltage is 24 volts, electric current during power supply in the winding wire of twin coil device is 0.48 ampere (big coil is the same with the electric current of small coil), by calculating, artificial vertical magnetic field, 1.2-1.4 rice is 23200-9600nT (1nT=1 * 10 under the coil central point
-9T).On basic point and each measuring point, all when not powering and powering, carried out repeated measures 3 to 4 times, averaged then.
The vertical magnetic field value that on basic point, measures when not powering and powering be respectively 40937nT and-49525nT (opposite for bear) with the geomagnetic field vertical component direction.
The vertical magnetic field value that on a measuring point of φ 273mm * 10mm steel pipe, measures when not powering and powering be respectively 50923nT and-35963nT, be 3579nT by calculate the magnetic field vertical component value that steel pipe produces under artificial magnetic field magnetization.The value that on another measuring point of φ 273mm * 10mm steel pipe, measures when not powering and powering be respectively 36374nT and-50750nT, be 3338T by calculate the magnetic field vertical component value that steel pipe produces under artificial magnetic field magnetization.
The value that on a measuring point of φ 377mm * 7mm pipe crimping, measures when not powering and powering be respectively 37916nT and-49189nT, be 3357nT by calculate the magnetic field vertical component value that pipe crimping produces under artificial magnetic field magnetization.The magnetic field vertical component value that on another measuring point of φ 377mm * 7mm pipe crimping, measures when not powering and powering be respectively 42613nT and-44330nT, be 3519nT by calculate the magnetic field vertical component value that pipe crimping produces under artificial magnetic field magnetization.
The mean value of the artificial magnetization magnetic field vertical component of two measuring points on φ 273mm * 10mm steel pipe is 3459nT, and difference is 241nT, is 7% of mean value.The mean value of the artificial magnetization magnetic field vertical component of two measuring points on φ 377mm * 7mm pipe crimping is 3438nT, and difference is 162nT, is 4.7% of mean value.All be covered with or once be covered with iron rust on these two steel pipes (weldless steel tube, pipe crimping), the corrosion of steel pipe, the sum of errors measuring error in the manufacture process all might cause this difference of measuring at the same different measuring point place of steel pipe.Consider when the equal rotten thickness of φ 273mm * 10mm steel pipe is 1 millimeter (be equivalent to steel pipe have ferromagnetic thickness partly reduce 1 millimeter), the artificial magnetization magnetic field vertical component of steel pipe will reduce about 346nT, and the artificial magnetization magnetic field vertical component of φ 377mm * 7mm pipe crimping will reduce about 491nT, and the sort of difference that different measuring points measures on same steel pipe validity that method of the present invention is detected the degree that is corroded of underground steel pipe does not have and has a strong impact on so.According to calculating, the twin coil device is also little in the magnetic field intensity at the steel pipe place of test, only is about 1/3rd of geomagnetic field intensity.If adopt than 24 volts of much higher power supplys, effect will be better.The Theoretical Calculation of carrying out shows, the magnetic field vertical component 74% directly over the uniform magnetic field magnetization underground steel pipe of endless down is that length equals a dark pipeline section and produces under the measuring point.For the magnetic field that the twin coil device produces, above-mentioned percentage is bigger certainly.According to (2) formula, can increase supply current by increasing supply voltage, thereby increase artificial magnetic field intensity, make the underground steel pipe section of being corroded segment length be 1 meter, during equal rotten thickness 1-2 millimeter artificial magnetization magnetic field vertical component be not corroded relatively steel pipe artificial magnetization magnetic field vertical component reduce enough greatly, can detect for the present invention.At present both at home and abroad the vertical field balance device measuring accuracy of producing all can reach 1nT or higher, and therefore, detecting the corrosion section that equal rotten thickness is equal to and greater than 1 meter of 1-2 millimeter, length with ground artificial magnetization method of the present invention is without a doubt.
The artificial magnetization magnetic field vertical component value that records on φ 273mm * 10mm weldless steel tube and the φ 377mm * 7mm pipe crimping is no wonder much at one, because both sectional areas are divided into 8258mm
2And 8133mm
2, only differing 1.6%, the steel amount that both do to contribute to magnetic field under the artificial magnetic field magnetization is more or less the same.
It generally is to be a hot spot more than the scope with 1 meter that the corrosion of steel pipe at present detects.Corrosion depth is a heavy corrosion greater than 4 millimeters; Corrosion depth is that moderate is corroded the 2-4 millimeter; Corrosion depth less than 2 millimeters be mild corrosion.According to maintenance requirement, the overhaul in time of heavy corrosion point.The method that ground artificial magnetization of the present invention detects underground steel pipe corrosion condition can satisfy above-mentioned requirement to detecting fully.
Two, embodiment (the detection of carrying out in Dalian) to the steel pipe that is not corroded and has been corroded:
Be assembled into steel pipe corrosion detector under the tableland with the twin coil device with at the CCM-4 vertical field balance that geological instrument factory in Beijing buys, be not corroded steel pipe and the steel pipe that has been corroded carried out the corrosion detection in Dalian.The be not corroded steel pipe and the steel pipe that has been corroded is the weldless steel tube of φ 220mm * 8mm, and length is 583mm, is that Dalian petroleum chemical enterprise provides; The heavy 25.3kg of the steel pipe that is not corroded, the heavy 21.8kg of the steel pipe that has been corroded.
During measurement, the coil of twin coil device, the steel pipe that is not corroded, the equal horizontal setting of steel pipe that is corroded, the steel pipe that is not corroded, the be corroded bottom branch of steel pipe is taken leave of 0.557 meter of the coil (measuring respectively) of twin coil device.The hub of a spool of twin coil device is positioned at the steel pipe that is not corroded, is corroded and (measures respectively) directly over the steel pipe when measuring point is measured.
During measurement with 48 volts of power supplys, electric current during power supply in the winding wire of twin coil device is 0.98 ampere (big coil is the same with the electric current of small coil), by calculating, under the coil central point, be not corroded steel pipe, the be corroded artificial vertical magnetic field, top place of steel pipe is 278000nT, the steel pipe that is not corroded, the be corroded artificial vertical magnetic field, 0.557 meter, bottom of steel pipe is 153000nT.All having carried out 3 to 4 repeated measures on basic point and each measuring point when not powering and powering averages then.
The vertical magnetic field value that on basic point, measures when not powering and powering be respectively 0nT (having compensated the terrestrial magnetic field) with small coil and-732nT (opposite for negative) with the geomagnetic field vertical component direction.
The vertical magnetic field value that measures on the steel pipe that is not corroded when not powering and powering is respectively-1552nT and 10952nT.
The vertical magnetic field value that measures on the steel pipe that is corroded when not powering and powering is respectively-4208nT and 12888nT.
By calculate the magnetic field vertical component value that the steel pipe that is not corroded produces under artificial magnetic field magnetization is 8668nT.By calculate the magnetic field vertical component value that the steel pipe that is corroded produces under artificial magnetic field magnetization is 7928nT.The magnetic field vertical component value that has been corroded steel pipe and produces under artificial magnetic field magnetization than the steel pipe that is not corroded is little 740nT.8668nT is the magnetic field value that the every mm of steel pipe can produce divided by 8mm, and its value is 1084nT/mm.Steel pipe is worth divided by this because of the magnetic field 740nT that corrosion reduces, and its value is 0.683mm, and it is the equal rotten thickness that calculates according to measurement result.Root is according to weighing results, and the steel pipe that has been corroded is lighter 3.5 kilograms than the steel pipe that is not corroded.The weight average that the every mm of the steel pipe that is not corroded is thick be 25.3kg divided by 8mm, equal 3.16kg/mm.So the actual equal rotten thickness of steel pipe be 3.5kg divided by 3.16kg/mm, equal to be 1.11mm.Because magnetic field is uneven, the steel pipe place of being corroded uneven distribution will cause equal rotten thickness of estimating according to measurement result and the equal rotten thickness that goes out according to steel pipe weight, the loss of steel amount and steel pipe THICKNESS CALCULATION that difference is arranged.But this measurement result has been enough to the mildly corrosive like this steel pipe of explanation also can be measured.The corrosion detection of carrying out underground steel pipe with floor file loop line generation magnetic field can obtain better result.
This example has proved the validity of the inventive method equally.
Claims (3)
1. ground artificial magnetization detects the method for underground steel pipe corrosion condition, it is characterized in that it comprises the steps:
1) select a basic point on ground, no iron and steel thing influence of magnetic field place, the emission of magnetic field device is settled on the ground, with the magnetic field vertical component value of magnetometer survey when the emission of magnetic field device is not powered of surveying vertical magnetic field, magnetic field vertical component value when obtaining basic point and not powering;
Then to the emission of magnetic field device for the village, the emission of magnetic field device is spatial emission magnetic field towards periphery, makes magnetic field with the same depth location of underground steel pipe depth value to be detected greater than 0.2 * 10
-4Tesla is with the magnetic field vertical component value of magnetometer survey when the emission of magnetic field device is powered of surveying vertical magnetic field, magnetic field vertical component value when obtaining the basic point power supply;
Magnetic field vertical component value when magnetic field vertical component value subtracts basic point and do not power when powering with basic point, the gained difference is basic point artificial magnetic field vertical component value;
2) the ground configuration measuring point directly over underground steel pipe to be detected, the emission of magnetic field device is placed in ground measuring point place, at the measuring point place earlier with the magnetic field vertical component value of magnetometer survey when the emission of magnetic field device is not powered of surveying vertical magnetic field, magnetic field vertical component value when obtaining measuring point and not powering;
To the power supply of emission of magnetic field device, the emission of magnetic field device is the spatial emission magnetic field identical with step 1) towards periphery then, with the magnetic field vertical component value of magnetometer survey when the emission of magnetic field device is powered of surveying vertical magnetic field, magnetic field vertical component value when obtaining the measuring point power supply;
Magnetic field vertical component value when magnetic field vertical component value subtracts measuring point and do not power when powering with measuring point, the gained difference is measuring point artificial magnetic field vertical component value;
3) measuring point artificial magnetic field vertical component value subtracts the magnetic field vertical component value that basic point artificial magnetic field vertical component value obtains the generation under the artificial magnetic field magnetization of measuring point place underground steel pipe;
4) size of the magnetic field vertical component value that produces under the above-mentioned artificial magnetic field magnetization according to each measuring point determines whether underground steel pipe has been corroded and the degree that is corroded; The magnetic field vertical component value numerical value that produces under this artificial magnetic field magnetisation is more little, illustrate be corroded serious more.
2. ground artificial magnetization according to claim 1 detects the method for underground steel pipe corrosion condition, it is characterized in that: described emission of magnetic field device is the twin coil device, and it comprises bracing frame (1), big coil (2), pin (3), small coil (4), second binding post (6); Bracing frame (1) is made up of big toroidal frame, little toroidal frame, connecting link, little toroidal frame is positioned at big toroidal frame, and little toroidal frame and big toroidal frame concentric, little toroidal frame is fixedlyed connected with big toroidal frame by at least 3 connecting links, is respectively equipped with ring groove on little toroidal frame, the big toroidal frame; Be wound with big coil (2) in the ring groove on the big toroidal frame, the two ends of big coil (2) link to each other with first binding post, second binding post (6) respectively; Be wound with small coil (4) in the ring groove on the little toroidal frame, the two ends of small coil (4) link to each other with the 3rd binding post, the 4th binding post respectively; Second binding post links to each other with the 3rd binding post or the 4th binding post, and it is opposite to make big coil and electric current in the small coil stream direction; First binding post links to each other with the both positive and negative polarity of power supply by lead, switch respectively with the 3rd binding post or the 4th binding post; The center pit internal fixation of little toroidal frame has the sensor of the magnetometer of surveying vertical magnetic field; Big coil (2) and small coil (4) are at grade; Be fixedly connected with that the 3-5 root is collapsible, the pin of adjustable length (3) end of big toroidal frame.
3. ground artificial magnetization according to claim 1 detects the method for underground steel pipe corrosion condition, and it is characterized in that: described emission of magnetic field device is the floor file loop line.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2008101978980A CN101408625B (en) | 2008-11-25 | 2008-11-25 | Method for detecting underground steel pipe corrosion condition by ground artificial magnetization |
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| CN2008101978980A CN101408625B (en) | 2008-11-25 | 2008-11-25 | Method for detecting underground steel pipe corrosion condition by ground artificial magnetization |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101694478B (en) * | 2009-11-05 | 2012-08-01 | 陈斯文 | Method for detecting internal corrosion of steel pipeline |
| CN106970143A (en) * | 2017-04-20 | 2017-07-21 | 武汉地大华睿地学技术有限公司 | A kind of method that contactless double source magnetic field comprehensive detects metallic conduit defect |
| CN107133328A (en) * | 2017-05-05 | 2017-09-05 | 国家测绘地理信息局四川测绘产品质量监督检验站 | Pipeline buried depth accuracy checking method and device |
| CN112664840A (en) * | 2020-12-14 | 2021-04-16 | 中国石油大学(北京) | Vector scanner and pipeline risk determination method |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3932282B2 (en) * | 2003-01-10 | 2007-06-20 | 住友金属パイプエンジ株式会社 | Corrosion protection coating damage detection device for buried piping |
| CN1206529C (en) * | 2003-07-08 | 2005-06-15 | 刘崧 | Gronnd surface electric measuing method for detecting underground metal pipeline corrusion state |
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2008
- 2008-11-25 CN CN2008101978980A patent/CN101408625B/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101694478B (en) * | 2009-11-05 | 2012-08-01 | 陈斯文 | Method for detecting internal corrosion of steel pipeline |
| CN106970143A (en) * | 2017-04-20 | 2017-07-21 | 武汉地大华睿地学技术有限公司 | A kind of method that contactless double source magnetic field comprehensive detects metallic conduit defect |
| CN107133328A (en) * | 2017-05-05 | 2017-09-05 | 国家测绘地理信息局四川测绘产品质量监督检验站 | Pipeline buried depth accuracy checking method and device |
| CN112664840A (en) * | 2020-12-14 | 2021-04-16 | 中国石油大学(北京) | Vector scanner and pipeline risk determination method |
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| CN101408625B (en) | 2011-05-18 |
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