CN102183229A - Ultrasonic detection method of scale thickness in pipeline - Google Patents

Abstract

The invention discloses an ultrasonic detection method of scale thickness in a pipeline. The method comprises the following steps of: utilizing double incidences of ultrasonic waves at different angles, establishing simultaneous equations on the basis of propagation velocities of the known ultrasonic wave on the pipe wall and in the filled fluid and the relationship between an incident angle and a refraction angle of the ultrasonic wave by measuring the penetration time of the ultrasonic waves in the pipeline filled with fluid during the double incidences, and further calculating the velocity and the thickness of a scale layer in the pipeline. With the method, the scale thickness can be measured under the condition that the scale characteristic is unknown, the working detection of the pipeline can be achieved, and the method has reliable accuracy and no destructive effect.

Description

The ultrasonic detection method of dirty layer thickness in a kind of pipeline

Technical field

The present invention relates to the ultrasonic detection method of dirty layer thickness in a kind of pipeline, belong to the Non-Destructive Testing field.

Background technology

In numerous industries such as petrochemical complex, metallurgy, thermoelectricity, ubiquity scale problems in various device and the pipeline.Dirt layer can dwindle the pipeline circulation area, increases transporting resistance, the position that fouling is serious even can result in blockage; In some heat-exchange systems, because the coefficient of heat conductivity of dirt is very little, the dirt layer can reduce heating surface heat transferred speed, causes heating surface temperature anomaly to raise, and has destroyed the physical strength of pipeline, has shortened the serviceable life of pipeline greatly, even can cause pipe explosion accident.

In order to prevent accident, reduce power consumption, need be to the timely pickling descaling of pipeline.This just must understand the situation of dirt layer in the pipeline in real time.The fouling situation of inner-walls of duct mainly with pumped (conveying) medium, working environment, use with a plurality of factors such as times relevant, the main pipe cutting mode that adopts is understood the fouling situation on the engineering at present, this method is long in time limit, destructive greatly, cost is high, have a strong impact on the normal operation of equipment, and can't effectively understand the fouling situation of whole pipe inwall.

Summary of the invention

Technical matters to be solved by this invention is to provide the ultrasonic detection method of dirty layer thickness in a kind of pipeline, and it does not have destructiveness to pipeline, and can detect in labour by pipeline.

The inventive method is to utilize the ultrasound wave incident respectively of twice different angles, the time of break-through of ultrasound wave in the pipeline of full of liquid when measuring twice incident, Simultaneous Equations on the basis of velocity of propagation, ultrasound wave incident angle and the refraction angle relation of known ultrasound wave in tube wall and filling liquid, and then calculate the speed of dirt layer in the pipeline and the dirty method of a kind of ultrasonic survey of thickness.

Particularly, technical scheme of the present invention may further comprise the steps successively:

(1) considers the travel-time of ultrasound wave in probe, adopt reference block to carry out instrument zero and check;

(2) on tested pipeline, select any surface finish and axially straight one section to install and survey anchor clamps, to the tested pipeline pre-service of polishing;

(3) measure close 4 outer diameter tube values and pipeline wall thickness, by coefficient of dispersion less than 0.8% condition, initial option sensing point;

(4) near the initial option sensing point, get 4 points, the measuring vertical time of break-through, by coefficient of dispersion less than 0.1% condition, final coordinate detection point;

(5) sensing point place pipeline wall thickness and sound wave penetrate the measurement in path

Measure the pipeline wall thickness δ at sensing point two ends respectively with audiogage ₁₁, δ ₁₂, both and be sensing point place pipeline wall thickness and δ ₁The acoustic wave propagation path D of pipeline when vertical penetration-detection is measured at the two ends of pipeline burnishing part;

(6) hypothesis of dirt layer ultrasonic propagation velocity value and dirty layer thickness value estimates;

Environment for use and empirical data according to pipeline suppose dirty layer ultrasonic propagation velocity v ₂, estimate out dirty layer thickness according to the saturating propagation law of direct puncture:

$\mathrm{\&delta;}=\frac{v_2{\mathrm{<figure-callout\; id="3"\; label="v"\; filenames="110225102019.png,110225102022.png"\; state="\{\{state\}\}">v</figure-callout>}}_3}{2(v_3-v_2)}(T_1-\frac{{\mathrm{\&delta;}}_1}{v_1}-\frac{D-{\mathrm{\&delta;}}_1}{v_3})\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(a\right)$

In the formula: T ₁: the travel-time of ultrasound wave in pipeline during vertical incidence, unit: second;

D: transonic path, unit: rice;

δ ₁: the thickness of tube wall and, unit: rice;

δ: the thickness of dirt, unit: rice;

v ₁: the speed that ultrasound wave is propagated in tube wall, unit: meter per second;

v ₂: the speed that ultrasound wave is propagated in dirt, unit: meter per second;

v ₃: the speed that ultrasound wave is propagated in liquid, unit: meter per second;

Then, can make estimation in advance to dirty one-tenth-value thickness 1/10 according to formula (a);

(7), judge the off-set value of angle probe incident direction in advance according to the discreet value of previous step dirt layer thickness; Adopt straight incident and oblique incidence mode to measure time T 1 and T2 that ultrasound wave penetrates pipeline respectively;

(8) the preliminary of sensing point place dirt interval velocity value and one-tenth-value thickness 1/10 determined

Can obtain formula (b) according to straight transmission propagation law:

${\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="110225102019.png,110225102022.png"\; state="\{\{state\}\}">T</figure-callout>}}_1=\frac{{\mathrm{\&delta;}}_1}{{\mathrm{<figure-callout\; id="1"\; label="v"\; filenames="110225102019.png,110225102022.png"\; state="\{\{state\}\}">v</figure-callout>}}_1}+\frac{2\mathrm{\&delta;}}{v_2}+\frac{D-{\mathrm{\&delta;}}_1-2\mathrm{\&delta;}}{v_3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(b\right)$

Can obtain formula (c) according to oblique transmission propagation law:

${\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="110225102019.png,110225102022.png"\; state="\{\{state\}\}">T</figure-callout>}}_2=\frac{{\mathrm{\&delta;}}_1}{v_1\mathrm{COS}{\mathrm{\&theta;}}_1}+\frac{2\mathrm{\&delta;}}{v_2\mathrm{COS}{\mathrm{\&theta;}}_2}+\frac{D-{\mathrm{\&delta;}}_1-2\mathrm{\&delta;}}{v_3\mathrm{COS}{\mathrm{\&theta;}}_3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(c\right)$

At different interfaces propagation law, can obtain the relational expression (d) of refraction angle and incident angle according to ultrasound wave:

Sinθ ₁/v ₁＝Sinθ ₂/v ₂＝Sinθ ₃/v ₃?……(d)

T in the formula ₂: the oblique travel-time of ultrasound wave in pipeline during penetration-detection, unit: second;

θ ₁: the oblique incidence ultrasound wave is in the incident angle at steel/dirty interface;

θ ₂: the oblique incidence ultrasound wave is in the refraction angle at steel/dirty interface and the oblique incidence ultrasound wave incident angle in dirt/liquid surface;

θ ₃: the oblique incidence ultrasound wave is at the refraction angle in dirt/liquid surface;

According to K=tan θ ₁, draw θ ₁Value, simultaneous (b), (c), (d) three formulas then adopt iteration Method to draw the propagation angle θ of ultrasound wave in the dirt layer ₂, speed v ₂And dirty layer thickness δ ₂

(9) the final of sensing point place dirt interval velocity value and one-tenth-value thickness 1/10 determined

According to speed of calculating and one-tenth-value thickness 1/10, rejudge the installation position of receiving transducer, and then carry out straight, tiltedly transmission, measure time of break-through, according to the formula (a) and (b) and (c) recalculate dirty velocity amplitude and one-tenth-value thickness 1/10;

If the velocity amplitude of twice calculating differs less than 0.1% of mean value, then this value is exactly the velocity amplitude that ultrasound wave is propagated in the dirt layer; Otherwise reorientate once more, measure, differ less than 0.1% of mean value until the velocity amplitude that twice measurement calculated, this moment, resulting velocity amplitude was exactly the velocity amplitude that ultrasound wave is propagated in the dirt layer;

According to the velocity amplitude of determined dirt, adopt straight incident method pipe under test to be carried out vertical penetration-detection in the sensing point place, can calculate the one-tenth-value thickness 1/10 of dirt according to formula (a).

In the technique scheme, need to prove, with (a) when formula is calculated dirty layer thickness, owing to the velocity of propagation of ultrasound wave in liquid can change along with the variation of fluid temperature, so following formula must be noted that temperature compensation when calculating.Utilize the temperature sensing device thermometric to realize that the velocity of sound compensates indirectly, eliminate the influence that temperature is brought detection, to improve measuring accuracy.

Compared with prior art, the present invention has obtained following technique effect:

(1) under the situation of unknown dirt layer character, measures dirty layer thickness.In nondestructiving detecting means in the past, detect the pipeline scale situation, must understand the character of dirt in the pipeline earlier.And the present invention can utilize ultrasound wave to penetrate signal measurement under the situation of unknown dirt layer character to go out dirty interval velocity, solved the problem of dirty layer character the unknown, and then measures dirty layer thickness.

(2) realized that pipeline detects in labour.During the pipeline on-line operation, inner full of liquid need not the emptying internal liquid during detection, and ultrasound wave can penetrate pipeline along diametric(al) by liquid, goes out dirty layer thickness thereby utilize ultrasound wave to penetrate signal measurement.

(3) there is not destructiveness.This technology need not pipe cutting and understands the fouling situation, can dynamically grasp the distribution of the pipeline dirt layer thickness of entire equipment, has significantly reduced the detection cost.In addition, because pipe cutting can be buried potential safety hazard to the utilization of reparation once more of pipeline, detection technique as herein described has then been avoided this problem.

(4) precision height.This method is by the advantage of ultrasound wave penetration-detection, can eliminate the interference of other factors such as dirty layering well, improve the accuracy of dirty interval velocity, thereby improve dirty layer thickness measuring accuracy, for scale removal provides scientific and effective reference frame, avoid the blindness scale removal on the engineering, guaranteed the safe operation of pipeline.

Description of drawings

Fig. 1 is an initial option sensing point process synoptic diagram

Fig. 2 is the principle schematic of the inventive method

Fig. 3 is the partial enlarged drawing of Fig. 2

Wherein: 1-tube wall, 2-dirt, 3-liquid, 4-normal probe, 5-angle probe.

Embodiment

Further the present invention is further elaborated below in conjunction with embodiment.

Specific implementation method of the present invention is as follows:

(1) adopt reference block to carry out check of zero

In the actual detected, ultrasound wave has one section travel path in probe, can influence the accuracy that dirty layer thickness value is measured during this section sound.Therefore, in order to improve accuracy of detection, we adopt reference block to carry out check of zero.

Select the reference block of a known velocity of sound known thickness for use, reach thoroughly with convenient clear and definite ultrasound wave direct puncture in reference block and tiltedly penetrate the required travel-time with different paths; Penetrate the difference in ultrasound wave travel-time in test block under T.T. and the respective detection mode when calculating actual detected then, promptly obtain the travel-time of ultrasound wave in probe under the different detection modes; At last, before workpiece is detected, directly import zero shift with digital form according to the difference under detection mode and the respective detection mode.

(2) the detection anchor clamps are installed

On tested pipeline, select any surface finish and axially straight one section to install and survey anchor clamps, survey anchor clamps be mainly used to polish pre-service and probe location.At first start grinding apparatus pipeline is carried out axially parallel polishing processing, guaranteed the collimation of the surface of emission and receiving plane on the one hand; Increase the contact area of probe and pipeline on the other hand, improved the acoustic coupling effect when detecting.After the completion of processing of polishing, on buffed surface, smear couplant, and, accurately locate popping one's head in according to the rule on the anchor clamps surveying installation probe on the anchor clamps; Survey anchor clamps and push artificial factor such as angle because of the dynamics of pushing of probe, probe in also having avoided simultaneously detecting.

(3) initial option sensing point, assurance detects the homogeneity of position outer diameter tube and tube wall

Referring to Fig. 1,, assess this point then and whether meet the detection requirement a bit tentatively electing sensing point as on the grinding face.The first step, with between these some place two parallel buffed surfaces of miking apart from d ₁, a side of this point is selected 3 points close with this point again on buffed surface then, measure respectively this some locate between two parallel buffed surfaces apart from d ₂, d ₃, d ₄If, d ₁, d ₂, d ₃, d ₄Between coefficient of dispersion less than 0.8%, then can carry out next step operation, otherwise reconnaissance again.Second the step, on the sensing point of initial option, measure near 4 pairing pipeline wall thickness with audiogage, if 4 the pipeline wall thickness coefficient of dispersion of locating of surveying less than 0.8%, represent that then the tube wall of this segment pipe on this buffed surface is more even; The even tube wall of in like manner assessing this segment pipe on another buffed surface whether.If above two steps assessment meets the requirements, then the selection before the expression can tentatively be decided to be sensing point.

(4) final coordinate detection point, assurance detect the homogeneity of position pipeline dirt layer thickness

Select the identical pair of straight probe of specification, frequency for use, pipeline is carried out vertical penetration-detection, draw time of break-through T according to vertical transmission Mintrop wave in the sensing point place ₁Adopt and use the same method, near sensing point on the buffed surface, once penetrate along the every 10mm of straight line, and their time of break-through relatively.Guaranteed the collimation of buffed surface, the homogeneity of pipe thickness during the initial option sensing point, got 4 continuous sensing points, if the coefficient of dispersion of the time of break-through that these points are surveyed, represents then that pipeline dirt layer thickness is even less than 0.1%.At this moment, just fixed point just can finally be elected sensing point as.

(5) sensing point place pipeline wall thickness and sound wave penetrate the measurement in path

Measure the pipeline wall thickness δ at sensing point two ends respectively with audiogage ₁₁, δ ₁₂, both and be sensing point place pipeline wall thickness and δ ₁Acoustic wave propagation path D with milscale pipeline when vertical penetration-detection is measured at the two ends of pipeline burnishing part.

(6) hypothesis of dirty velocity amplitude and dirty one-tenth-value thickness 1/10 estimates

Estimate the ultrasonic propagation velocity that the dirt layer substantially according to the environment for use of pipeline.

Can draw the computing formula (a) of dirty layer thickness according to the saturating propagation law that detects of direct puncture:

$\mathrm{\&delta;}=\frac{v_2{\mathrm{<figure-callout\; id="3"\; label="v"\; filenames="110225102019.png,110225102022.png"\; state="\{\{state\}\}">v</figure-callout>}}_3}{2(v_3-v_2)}(T_1-\frac{{\mathrm{\&delta;}}_1}{v_1}-\frac{D-{\mathrm{\&delta;}}_1}{v_3})\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(a\right)$

In the formula: T ₁: the travel-time of ultrasound wave in pipeline during vertical incidence, unit: second;

D: transonic path, unit: rice;

δ ₁: the thickness of tube wall and, unit: rice;

δ: the thickness of dirt, unit: rice;

v ₁: the speed that ultrasound wave is propagated in tube wall, unit: meter per second;

v ₂: the speed that ultrasound wave is propagated in dirt, unit: meter per second;

v ₃: the speed that ultrasound wave is propagated in liquid, unit: meter per second;

Then, can make estimation in advance to dirty one-tenth-value thickness 1/10 according to formula (a).Need to prove, owing to the velocity of propagation of ultrasound wave in liquid can change along with the variation of fluid temperature, so following formula must be noted that temperature compensation when calculating.

Temperature compensation when (7) formula calculates

The velocity of propagation of ultrasound wave in liquid is different along with the difference of fluid temperature, and is subjected to Temperature Influence bigger.So, when formula calculates,, utilize the temperature sensing device thermometric to realize that the velocity of sound compensates indirectly according to the relation between liquid acoustic velocity and the temperature, eliminate the influence that temperature is brought detection, to improve measuring accuracy.

(8) adopt the oblique incidence mode to measure the time T that ultrasound wave tiltedly penetrates pipeline ₂

Select a pair of specification identical, promptly the identical angle probe of parameter such as K value, forward position length is placed in sensing point with transmitting probe; According to the discreet value of previous step dirt layer thickness, can judge the off-set value of angle probe incident direction in advance, thereby find out the probe mounting position of reception; Then workpiece is carried out oblique penetration-detection, obtain oblique time of break-through T according to oblique transmission Mintrop wave ₂

(9) the preliminary of sensing point place dirt interval velocity value and one-tenth-value thickness 1/10 determined

Can obtain formula (b) according to straight transmission propagation law:

${\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="110225102019.png,110225102022.png"\; state="\{\{state\}\}">T</figure-callout>}}_1=\frac{{\mathrm{\&delta;}}_1}{{\mathrm{<figure-callout\; id="1"\; label="v"\; filenames="110225102019.png,110225102022.png"\; state="\{\{state\}\}">v</figure-callout>}}_1}+\frac{2\mathrm{\&delta;}}{{\mathrm{<figure-callout\; id="2"\; label="v"\; filenames="110225102019.png,110225102022.png"\; state="\{\{state\}\}">v</figure-callout>}}_2}+\frac{D-{\mathrm{\&delta;}}_1-2\mathrm{\&delta;}}{{\mathrm{<figure-callout\; id="3"\; label="v"\; filenames="110225102019.png,110225102022.png"\; state="\{\{state\}\}">v</figure-callout>}}_3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(b\right)$

Can obtain formula (c) according to oblique transmission propagation law:

${\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="110225102019.png,110225102022.png"\; state="\{\{state\}\}">T</figure-callout>}}_2=\frac{{\mathrm{\&delta;}}_1}{{\mathrm{<figure-callout\; id="1"\; label="v"\; filenames="110225102019.png,110225102022.png"\; state="\{\{state\}\}">v</figure-callout>}}_1\mathrm{COS}{\mathrm{\&theta;}}_1}+\frac{2\mathrm{\&delta;}}{{\mathrm{<figure-callout\; id="2"\; label="v"\; filenames="110225102019.png,110225102022.png"\; state="\{\{state\}\}">v</figure-callout>}}_2\mathrm{COS}{\mathrm{\&theta;}}_2}+\frac{D-{\mathrm{\&delta;}}_1-2\mathrm{\&delta;}}{{\mathrm{<figure-callout\; id="3"\; label="v"\; filenames="110225102019.png,110225102022.png"\; state="\{\{state\}\}">v</figure-callout>}}_3\mathrm{COS}{\mathrm{\&theta;}}_3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(c\right)$

At different interfaces propagation law, can obtain the relational expression (d) of refraction angle and incident angle according to ultrasound wave:

Sinθ ₁/v ₁＝Sinθ ₂/v ₂＝Sinθ ₃/v ₃?……(d)

T in the formula ₂: the oblique travel-time of ultrasound wave in pipeline during penetration-detection, unit: second;

θ ₁: the oblique incidence ultrasound wave is in the incident angle at tube wall/dirty interface;

θ ₂: the oblique incidence ultrasound wave is in the refraction angle at tube wall/dirty interface and the oblique incidence ultrasound wave incident angle in dirt/liquid surface;

θ ₃: the oblique incidence ultrasound wave is at the refraction angle in dirt/liquid surface;

In addition, the K value of angle probe is known, can be according to K=tan θ ₁, draw θ ₁Value, simultaneous (b), (c), (d) three formulas then adopt iteration Method to draw the propagation angle θ of ultrasound wave in the dirt layer ₂, speed v ₂And dirty layer thickness δ ₂

(10) the final of sensing point place dirt interval velocity value and one-tenth-value thickness 1/10 determined

Because sensitivity was relatively low when tiltedly transmission detected, signal to noise ratio (S/N ratio) is low, and the positioning error of receiving transducer is relatively large, therefore needs to rejudge the installation position of receiving transducer according to the speed and the one-tenth-value thickness 1/10 of calculating.Then, carry out straight, tiltedly transmission once more, measure time of break-through, according to the formula (a) and (b) and (c) recalculate dirty velocity amplitude and one-tenth-value thickness 1/10.If the difference of the velocity amplitude of twice calculating is less than 0.1% of mean value, then this value is exactly the velocity amplitude that ultrasound wave is propagated in the dirt layer; Otherwise reorientate once more, measure, less than 0.1% of mean value, this moment, resulting velocity amplitude was exactly the velocity amplitude that ultrasound wave is propagated in the dirt layer until the difference of the velocity amplitude that twice measurement calculated.

According to the velocity amplitude of determined dirt, adopt straight incident method pipe under test to be carried out vertical penetration-detection in the sensing point place, can calculate the one-tenth-value thickness 1/10 of dirt according to formula (a).

(11) near other position dirt layer thickness of sensing point determines

In order to measure dirty interval velocity value, the selected sensing point in front has guaranteed certain detection condition.And near other position the sensing point may exist elbow or dirt situation such as in uneven thickness, because of near the extremely one section working environment of sensing point on the pipeline identical, the character of formed dirt is close, the dirty interval velocity value that this moment, we can utilize the sensing point place to measure is measured the thickness of other position dirts.

Claims (3)

1. the ultrasonic detection method of dirty layer thickness in the pipeline, it is characterized in that: utilize the ultrasound wave incident respectively of twice different angles, the time of break-through of ultrasound wave in the pipeline of full of liquid when measuring twice incident, Simultaneous Equations on the basis of velocity of propagation, ultrasound wave incident angle and the refraction angle relation of known ultrasound wave in tube wall and filling liquid, and then calculate pipeline interior dirty layer speed and thickness.

2. ultrasonic detection method as claimed in claim 1 is characterized in that in turn including the following steps:

(1) considers the travel-time of ultrasound wave in probe, adopt reference block to carry out instrument zero and check;

(2) on tested pipeline, select any surface finish and axially straight one section to install and survey anchor clamps, to the tested pipeline pre-service of polishing;

(3) measure close 4 outer diameter tube values and pipeline wall thickness, by coefficient of dispersion less than 0.8% condition, initial option sensing point;

(4) near the initial option sensing point, get 4 points, the measuring vertical time of break-through, by coefficient of dispersion less than 0.1% condition, final coordinate detection point;

(5) sensing point place pipeline wall thickness and sound wave penetrate the measurement in path

Measure the pipeline wall thickness δ at sensing point two ends respectively with audiogage ₁₁, δ ₁₂, both and be sensing point place pipeline wall thickness and δ ₁The acoustic wave propagation path D of pipeline when vertical penetration-detection is measured at the two ends of pipeline burnishing part;

(6) hypothesis of dirt layer ultrasonic propagation velocity value and dirty layer thickness value estimates

Environment for use and empirical data according to pipeline suppose dirty layer ultrasonic propagation velocity v ₂, estimate out dirty layer thickness according to the saturating propagation law of direct puncture:

$\mathrm{\&delta;}=\frac{v_2{v}_3}{2(v_3-v_2)}(T_1-\frac{{\mathrm{\&delta;}}_1}{v_1}-\frac{D-{\mathrm{\&delta;}}_1}{v_3})\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(a\right)$

In the formula: T ₁: the travel-time of ultrasound wave in pipeline during vertical incidence, unit: second;

D: transonic path, unit: rice;

δ ₁: the thickness of tube wall and, unit: rice;

δ: the thickness of dirt, unit: rice;

v ₁: the speed that ultrasound wave is propagated in tube wall, unit: meter per second;

v ₂: the speed that ultrasound wave is propagated in dirt, unit: meter per second;

v ₃: the speed that ultrasound wave is propagated in liquid, unit: meter per second;

Then, can make estimation in advance to dirty one-tenth-value thickness 1/10 according to formula (a);

(7), judge the off-set value of angle probe incident direction in advance according to the discreet value of previous step dirt layer thickness; Adopt straight incident and oblique incidence mode to measure time T 1 and T2 that ultrasound wave penetrates pipeline respectively;

(8) the preliminary of sensing point place dirt interval velocity value and one-tenth-value thickness 1/10 determined

Can obtain formula (b) according to straight transmission propagation law:

$T_1=\frac{{\mathrm{\&delta;}}_1}{v_1}+\frac{2\mathrm{\&delta;}}{v_2}+\frac{D-{\mathrm{\&delta;}}_1-2\mathrm{\&delta;}}{v_3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(b\right)$

Can obtain formula (c) according to oblique transmission propagation law:

$T_2=\frac{{\mathrm{\&delta;}}_1}{v_1\mathrm{COS}{\mathrm{\&theta;}}_1}+\frac{2\mathrm{\&delta;}}{v_2\mathrm{COS}{\mathrm{\&theta;}}_2}+\frac{D-{\mathrm{\&delta;}}_1-2\mathrm{\&delta;}}{v_3\mathrm{COS}{\mathrm{\&theta;}}_3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(c\right)$

At different interfaces propagation law, can obtain the relational expression (d) of refraction angle and incident angle according to ultrasound wave:

Sinθ ₁/v ₁＝Sinθ ₂/v ₂＝Sinθ ₃/v ₃ ……(d)

T in the formula ₂: the oblique travel-time of ultrasound wave in pipeline during penetration-detection, unit: second;

θ ₁: the oblique incidence ultrasound wave is in the incident angle at steel/dirty interface;

θ ₂: the oblique incidence ultrasound wave is in the refraction angle at steel/dirty interface and the oblique incidence ultrasound wave incident angle in dirt/liquid surface;

θ ₃: the oblique incidence ultrasound wave is at the refraction angle in dirt/liquid surface;

According to K=tan θ ₁, draw θ ₁Value, simultaneous (b), (c), (d) three formulas then adopt iteration Method to draw the propagation angle θ of ultrasound wave in the dirt layer ₂, speed v ₂And dirty layer thickness δ ₂

(9) the final of sensing point place dirt interval velocity value and one-tenth-value thickness 1/10 determined

According to speed of calculating and one-tenth-value thickness 1/10, rejudge the installation position of receiving transducer, and then carry out straight, tiltedly transmission, measure time of break-through, according to the formula (a) and (b) and (c) recalculate dirty interval velocity value and one-tenth-value thickness 1/10;

If the difference of the velocity amplitude of twice calculating is less than 0.1% of mean value, then this value is exactly the velocity amplitude that ultrasound wave is propagated in the dirt layer; Otherwise reorientate once more, measure, less than 0.1% of mean value, this moment, resulting velocity amplitude was exactly the velocity amplitude that ultrasound wave is propagated in the dirt layer until the difference of the velocity amplitude that twice measurement calculated;

According to the velocity amplitude of determined dirt, adopt straight incident method pipe under test to be carried out vertical penetration-detection in the sensing point place, can calculate the one-tenth-value thickness 1/10 of dirt according to formula (a).

3. ultrasonic detection method as claimed in claim 2 is characterized in that, when formula is calculated dirty layer thickness, the velocity of propagation of ultrasound wave in liquid is being carried out temperature compensation with (a).

Images