CN105158280B - Prospect of Digital-Radiography accurately detects the defect of material and the method for thickness - Google Patents

Abstract

Prospect of Digital-Radiography accurately detects that the defect of material and the method for thickness belong to field of non destructive testing.The test block with fixed slope, it is positioned on detected material, when field of radiation from top to bottom is also cross examined workpiece and during the test block with fixed slope, receiving flat board by digital radial receives the ray after decay, and two dimensional image is converted into by data display processing unit；For flat board weld seam detection, the test block with fixed slope is placed on beside examined workpiece；The test block is the test block that section is right-angled trapezium, and wherein right-angle side horizontal positioned and workpiece are on a horizontal plane；For small diameter tube detection, with the band slope test block that section is semi-circular shape, the section of the test block axial direction is semi-circular shape, and the section of circumferential direction is right-angled trapezium；Section is equal to the external diameter of small diameter tube for the internal diameter with slope test block of semi-circular shape, and test block tight is placed on beside weld seam outside examined workpiece.The method can accurately measure height, weld reinforcement of defect etc., be not in erroneous judgement.

Description

Prospect of Digital-Radiography accurately detects the defect of material and the method for thickness

Technical field

The defect of material and the method for thickness are accurately detected the invention discloses Prospect of Digital-Radiography, belongs to lossless inspection Survey field.

Background technology

1st, industrial x-ray transillumination technology

Radioscopy belongs to one kind of Non-Destructive Testing, has X-ray procedure, gamma-ray examination, high-energy ray to examine and neutron The methods such as radioscopy.For industrial x-ray inspection, X-ray procedure and gamma-ray examination are typically used.Its principle It is：When the beam transillumination of even intensity penetrates object, if object regional area existing defects or structure have differences, it will Change decay of the object to ray so that different parts transmitted ray intensity is different, so, using certain detector (for example, Film is used in radiography) detection transmitted ray intensity, it is possible to defect and material distribution inside judgment object etc., so that Complete the inspection to detected object.

With the development of electronics and computer technology, (it is converted into using flat panel detector by changing the X-ray that will be penetrated Digital data transmission shows to computer, saves know clearly film and the process developed a film) X-ray direct imaging detection (DR) system is Start to be widely used in the fields such as industry, safety, research, medical treatment.Digital x-ray DR technologies have detection speed fast, sensitive Degree is high, analysis method is enriched, radiates the remarkable advantages such as low, no material consumption.

2nd, the relevant criterion of industrial non-destructive X-ray procedure and test block detection method are introduced

In June, 2013, No. four decree of chairman that President Xi Jinping promulgates,《People's Republic of China's special equipment peace Quan Fa》From on January 1st, 2014 formally implement, special equipment include boiler, pressure vessel, pressure pipeline, elevator, hoisting machinery, Passenger aerial ropeway, large-scale recreation facility, field (factory) interior private motor vehicle etc..These equipment typically have in high pressure, high temperature, height The characteristics of being run under empty, high-speed condition, inflammable, explosive, easy generation falling from high altitude etc., there is larger danger to the person and property safety Property.Special equipment production, manage, using, examine, detection should observe relevant special safety equipment technical specification and related mark It is accurate.

As the ray detection (radiology) of one of five big conventional lossless detection methods, have in industrial nondestructive testing Application widely.The industries such as Aero-Space, electric power, national defence, electric power have the industry examination criteria of correlation for detection And code.《People's Republic of China (PRC) professional standard JB/4730》With《Using Regular Inspection of Pressure Pipelines code》, define ray Requirement, process, detection performance rating classification, the definition of defect, measuring method of detection etc..Win as follows：

JB/T 4730《Bearing device Non-Destructive Testing》Table 6

The maximum of incomplete fusion oneself height in the single welding point that pipeline at different levels was allowed

4730 table 2l pipe outer diameter Ds₀>The lack of penetration classification of backing plate single welding is not added with during 100mm

Analyzed from above standard and clause, for manufacturing process and with detection, for pipeline " it is lack of penetration ' do not melt Close depth and be required for accurate measure, assay method is provided by 4730 standards, is carried out using reference block.

The size of the special reference block of small diameter tube (I types) see the table below (unit mm)

Standard it further provides that the general reference block that caliber is more than 100mm uses bar shaped test block, and its flaw size see the table below (winning JB4730 national standards).

The size mm of table H.2 general reference block (II types)

Standard content and discussion are won by above-mentioned, it is understood that：Current Standards for Pipeline welding Defects (it is lack of penetration, do not merge, Undercut etc.) grading be the blackness that defective locations are contrasted by step bar, then size by defect divided by the nominal of pipeline it is thick Degree, carries out grading evaluation.

Other standards, such as electric power standard《DL/T821-2002》, oil, national military standard etc. use similar definition and measurement Method：Direct blackness comparison is carried out using gradient comparison test block.

It can be summarized by description above：Existing defect depth measurement and grading, are all the ladder contrasts with strip or groove profile What the image blackness of test block and the shadow shape blackness contrast of defect were realized.And the shortcoming that these methods are present is discussed below：

1st, the problem of traditional radiographic photograph detection (measurement film density) is present：

1), accuracy of reading error：Effective blackness scope of film is about 1.5-4.0, and human eye is 0.006- depending on other ability 0.008, about 500 ranks, nigrometer is in measurement film density, and standard regulation error level is about 0.05, film density meter Measurement rank be 0.05 grade, every 0.05 blackness is rank, in effective blackness scope, 1.5-4.0, (4.0-1.5)/ 0.05=50 grades, rank is relatively low, and measuring accuracy is restricted.Blackness (being also gray scale) is 14 or 16 when using digital radial Position, the tonal range 16000 or 65000 of response, precision is higher than film.

2), measurement error：The defect that measure depth is generally required in workpiece is fine rule type, its spy shown on film It is thin black line to levy, such as lack of penetration, incomplete fusion, undercut etc., and the width of such defect is general even more small in below 0.5MM, and The well width of groove profile reference block is 2MM, and for measuring nigrometer, its syringe needle got ready is grade, when for determining During the blackness of groove profile test block groove, its position can be found accurately, when determining fault location blackness, it tends to be difficult to find its position accurately, one is Defect width is much smaller than syringe needle width, and two be that egative film is black under available light, and human eye is difficult to distinguish the accurate position of its defect Put, so measurement error is larger.Equally, processing (temperature, liquid medicine, developing time, film keep environment etc.) difference of film The difference of measurement result can be caused.In addition, the eyesight influence of operating personnel, level of skill can also influence measurement result.

2nd, for digital number ray：

Current indistinction is in the Special test block of film, and (JB/4730.11 has been changed to correlation standard in the recent period NB47013, starts a surname and pass through July) it may be referred to (film) standard execution as described above, but the method without specific implementation, step Suddenly, require.When current reference block is used for digital radial (DR), although some shortcomings of film detection, but numeral can be removed Ray detection has the characteristics of it is different from conventional film, and these it is exclusive the characteristics of to judging to bring trouble.Current comparison Test block there is a problem in that：

1) nigrometer comparative observation, is used before, and film density scope is typically that 1.5-4.0. scopes are small to the maximum, and numeral is penetrated Risen and fallen on big 1.6 ten thousand or 6.5 ten thousand gray levels of tonal range of line, gradation of image sense organ very big.It is not easy to choose benchmark click-through Row is compared.See that one section of straight line its grey level (curve of the coordinate inframe) fluctuating chosen on Fig. 1, homogenous pipe wall is very big：

2), each ladder of step bar is right angle, (comparing the high 1-2 order of magnitude of film) higher for luminous sensitivity Digital radial for, scattering influence from sense organ for it is bigger.If Fig. 2 is the band step bar (groove profile) that digital radial is shot Pipeline interface display, wherein linear graph shows the image of the marginal portion of right angle groove, sees the position that mark is drawn a circle, theoretical On should be right angle, due to scattering effect its be the transition numerical value gray scale with shake.Such case meeting in reality detection Cause user can not confirm the exact position compared.

3rd, more important point is that above-mentioned two methods there is a possibility that to judge (inaccurate) by accident:

The standard and method implemented at present, only measurement defective locations absolute grayscale, again with artificial defect in gradient test block Gray scale contrasted, judged with this defect height whether exceed test block on artificial defect.But, the method is not filled Divide the influence for considering weld reinforcement change and being brought to gray scale (gray scale depends on the thickness truly penetrated).Such as GB50235《Industry Metallic conduit job specfication》It is required that reinforcement≤the 1+0.2b (b is weld groove width) and no more than 3mm, institute of butt weld Construction reference disclosure satisfy that with reinforcement during actual welding within the specific limits.But during Site Detection, height is fixed not to be merged Defect, when appearing in reinforcement 2mm and 1mm reinforcement, its final gray scale necessarily has difference, and may be led during test block contrast Cause rating result can be different.

And the newest standards NB/T47013 (substituting JB/4730 latest edition, September is implemented on the 1st) that in April, 2015 promulgates It is required that considering reinforcement difference, and test block is manufactured according to reinforcement height (thickness of test block is equal to reinforcement height), but still used The mode of step bar intensity contrast.But, welding surroundings, personnel's difference of actual field etc. determine the scope of reinforcement very Greatly, and the reinforcement of same weld seam rises and falls also than larger, test block is highly difficult to determine；Such as, during weld seam big rise and fall, how Reference block is made not to be described.

The content of the invention

The present invention can solve the problem that above-mentioned all problems.Specifically it is discussed below：

General principle foundation：Under the conditions of equal transillumination, ray is equal through its gray scale after the workpiece of the same material of equal thickness； Equally, when transillumination condition is identical, the material thickness that the position of same grayscale is penetrated is also equal.

The present invention proposes set of system, including the test block with fixed slope, is positioned on detected material, when on to Under field of radiation also cross examined workpiece and during the test block with fixed slope, flat board is received by digital radial and receives decay Ray afterwards, two dimensional image is converted into by data display processing unit；

When flat board weld seam detection, the test block with fixed slope is placed on beside examined workpiece；The test block is for section The test block of right-angled trapezium, wherein right-angle side horizontal positioned and workpiece are on a horizontal plane；

For small diameter tube detection, with the band slope test block that section is semi-circular shape, the section of the test block axial direction is half Annular, the section of circumferential direction is right-angled trapezium；Section is equal to small diameter tube for the internal diameter with slope test block of semi-circular shape External diameter, test block tight is placed on beside weld seam outside examined workpiece；

There is stomata (reinforcement inner white region) in the middle of butt plates welding seam (black examined workpiece in Fig. 3), right side is therewith It is close to be placed the test block (white portion) with slope, when field of radiation from top to bottom is through examined workpiece and with fixed oblique During the test block of rate, flat board is received by digital radial and receives the ray after decay, is changed by data display processing unit (computer) Into two dimensional image (Fig. 3 birds-eye perspective).

The method implemented is：The known test block (length and height on inclined-plane are fixed) with fixed slope be positioned over by Detect on material, detected using digital radial DR, the characteristics of can realizing digitized processing using image, can be by with ash Degree inquiry, finds the position with defective locations gray scale equal slopes test block, so as to calculate the thickness of the point according to the slope of test block Degree.By taking flat board weld seam detection as an example, illustrated with Fig. 3：

There is stomata (reinforcement inner white region) in the middle of butt plates welding seam (black examined workpiece in Fig. 3), right side is therewith It is close to be placed the test block 4 with slope, the test block is the test block that section is right-angled trapezium, wherein right-angle side horizontal positioned and work Part 3 is on a horizontal plane (white portion), when the field of radiation 2 of X-ray machine X 1 from top to bottom is through examined workpiece and with fixation During the test block of slope, flat board 5 is received by digital radial and receives the ray after decay, by data display processing unit (computer) 6 It is converted into two dimensional image.

On the two dimensional image of production, when streaking straight line through slope test block and defective locations, computer can be shown Go out the grey scale change figure of this line, see that Fig. 4 illustrates.Weld reinforcement position (ray energy loss larger) gray scale is minimum, through lacking (energy loss is smaller) gray scale is maximum when falling into position, and the X-ray energy for penetrating slope test block part is lost with the change of thickness And change, so gray scale is approximately an oblique line.

In Fig. 4, because L is the projected length of test block (length of actual test block is L0, sees Fig. 5).Found by computer The position (dotted line shown in) equal with (gray scale minimum) gray scale at weld reinforcement in slope test block, by its length coordinate throwing Shadow calculates L1 length.Equally, position equal with weld defect (gray scale is maximum) gray scale in slope test block is found, by throwing Shadow calculates L2 length.

The physical parameter of test block is known, with reference to test block side cross-sectional, view：

L0：The length of test block, it is known that amount

L1、L2：Computer has been measured

H：(band slope portion) height of test block, it is known that amount

So, the relative altitude H1 of weld reinforcement position gray scale can be calculated by formula：

H1=(H/L0) * L1* (L0/L) draw the height of weld reinforcement (relative altitude only corresponds to slope portion)

(note：The gross thickness of the nominal wall thickness of minimum constructive height+pipeline of this numerical value+slope test block=reinforcement position)

Same method can calculate the relative altitude H2 of gray scale at weld defect：

H2=(H/L0) * L2* (L0/L) (relative altitude only corresponds to slope portion)

Both subtract each other the height for obtaining defective locations：Flaw height=H1-H2.

The method can accurately measure the height of defect, can also measure thinned (the test block thickness range of weld reinforcement, workpiece It is adapted to) etc., the shape of test block is not at the same time it can also measuring the tested object material thickness such as tubulose, tabular and position while welding Thickness and flaw height.

Summarize operation element flow as shown in Figure 6.

For small diameter tube, with the band slope test block that section is semi-circular shape.Specific practice can be hollow round table, hollow Cylinder is shaped as, identical two halves are cut into then along axis, section in the axial direction is right-angled trapezium, so

Concrete principle is：When the X-ray that X-ray machine X is launched penetrates small diameter tube, what the X-ray of diverse location was actually passed through Material thickness is differed, and sees that Fig. 9 illustrates, the thickness of A, B, C point penetrable material differs greatly, and (central ray penetration thickness is most Small, both sides become big；The pipeline being relatively large in diameter then difference very little, the bigger difference of caliber is smaller).If, test block is in strip and put Be placed in that (the corresponding pipeline location of B points) in the middle of pipeline carry out transillumination and measure be pipeline marginal position when, then due in pipeline The actual (real) thickness that the ray of heart line both sides is penetrated becomes larger and (is more than B see Fig. 9, A and C penetration thickness), then can cause gray scale Taper into；During in the presence of such grey scale change, the thickness and defect of A and C points can not be just measured with the slope test block of B points position Highly.

(on the right of weld seam, see outside examined workpiece and beside weld seam for semi-circular shape tight if section is made in test block Figure 10), then can ensure the measurement position of whole weld seam scope (projection) has the test block axially in parallel with pipeline along the y-axis direction Slope gray scale is contrasted, it is to avoid gamma error caused by thickness change.

When ray is aimed downwardly from the top in picture, digital radial flat receiver generation two dimensional image.In image On, when being drawn a straight line through slope test block and defective locations parallelpiped axial direction, computer can show this line Continuous gray scale change curve, is shown in Figure 12 signals (figure and plate welding before detect that picture is just the same)；Because test block is Section is semi-circular shape, so the grey scale curve avoids pipeline center and the side when (synchroballistic) ray penetrates small diameter tube Edge thickness differs greatly the influence brought.Ensuing detecting step and computational methods with discuss before it is identical.

The key problem in technology point of the present invention and to be intended to protect be a little what

1st, it is used for the guarantor that digital radial DR detection techniques (being free of CT) are used Thickness sensitivity using with fixed slope test block Shield, the lossless decomposition including pipeline, flat board, throat depth detection and material internal defect height detection.

2nd, under the conditions of using equal transillumination, the equal principle of the thickness of gray scale identical point passes through fixed slope test block meter Calculate material relative thickness, the method for flaw height.

Brief description of the drawings：

Fig. 1 is one section of straight line its grey level chosen on homogenous pipe wall.

Fig. 2 is the pipeline interface display of the band step bar (groove profile) shot for digital radial,

Fig. 3 is apparatus of the present invention schematic diagram.

Fig. 4 is from left to right direction gray scale and detects schematic diagram after computer generated image

Fig. 5 is with reference to test block sectional view

Fig. 6 is workflow diagram.

Fig. 7 is test block side view section figure

Fig. 8 is test block stereogram

Fig. 9 is that pipe with small pipe diameter ray penetrates schematic diagram

Figure 10 test block layout drawings

Figure 11 test block schematic diagrames

Figure 12 gray scales and detects schematic diagram

Embodiment

Time：On July 15th, 2015

Workpiece situation：Steel plate+band slope test block+gradient step bar

Testing goal：Checking measures two defects of gradient test block with (steel plate) background using with fixed slope test block Depth difference (flaw height inside simulation weld seam)

The equipment introduction used：

Equipment：Using the flat panel detector of U.S.'s Varian 2520

Using Belgian ICM companies CP160 X-ray machine Xs

Workpiece and test block description：

1st, 7mm steel plates, as background (thickness of simulation pipeline or flat board)

2nd, 3.5mm thicker strip have 5 step trough test blocks (see the H.2II type reference block of table above, depth is respectively 0.5, 1.0th, 1.5,2.0,2.5), first defect (depth 0.5mm, test block real surplus thickness 3mm) and second is used only in we The depth difference of defect (depth 1mm, test block real surplus thickness 2.5mm) simulates the flaw height in weld reinforcement.

3rd, the test block of thickness 2--3.5mm fixed slopes, effective length 11.5mm, as shown in Figure 7：

Note：The consideration of test block manufacture：

A, band fixed slope：This experiment is, 1.5:11.5

B and tested material same material, same to condition, (same material steel)

C, the gray scale of guarantee measured position can find equal point in slope test block tonal range.

Detection method：

The test block with slope and the test block with step trough are firmly pasted in 7mm surface of steel plate plastic adhesive tape.Use electricity Press 120KV, electric current 0.3mA, 1 second transillumination time, using 10 two field pictures superposition by the way of, obtain image, through handle it is as follows：

Calculating process：

It can be obtained by explanation before, the height H=3.5-2=1.5mm of slope test block, length L0=11.5；Throw The L=11.51 that shadow is obtained；

The corresponding H1 positions of gray scale of the position of defect 1 are found, H1=(1.5/11.5) * 7.84* are measured through formula (11.5/11.51)=1.02 (round up) mm；

Same manner finds the corresponding H2 positions of position gray scale of defect 2, and H2=(1.5/11.5) * is measured through formula 4.26* (11.5/11.51)=0.56mm (rounding up)；

The difference of defect 1 and defect 2 is：H1-H2=1.02mm-0.56mm=0.46mm

Due to the gradient of each groove of step bar (made according to national standard and have certificate of measurement and weight) be 0.5 millimeter ( Know), so this test error is：

(0.5-0.46)/0.5=0.08

Effect of the present invention

1st, relative thickness, the thickness of defective locations of optional position can be more accurately measured, defect is obtained after subtracting each other Precise height.

2nd, because this method is using the method for comparing measurement absolute value, so this method is applied to abnormally-structured inspection Survey.Such as aircraft blade, due to complicated, the method before the Minute pores use occurred in its manufacturing process is less susceptible to Detected (difference in thickness is big, complex-shaped, defect again very little, cause test block be difficult manufacture), if using this method, only examined The problem of total penetration thickness and defect definition for considering blade can make test block, measurement flaw height can then solve.

3rd, in addition to strip test block (this experiment is used), the test block can make the weld seam that semi-circular is used to detect small diameter tube Flaw height in reinforcement thickness and reinforcement.JB4730.2 standards (ray detection) regulation, pipe of the pipe external diameter equal to less than 100mm Road is small diameter tube, and the ladder reference block of small diameter tube needs to be detected using semicircle test block (to be contrasted see the above type of small diameter tube I Test block requirement)；This inventive method is equally applicable to the principle.It is using semicircle (band slope) test block reason：Work as X-ray machine X When the X-ray of transmitting penetrates small diameter tube, the material thickness that the X-ray of diverse location is actually passed through is differed, and sees that Fig. 9 shows Meaning, the thickness of A, B, C point penetrable material differs greatly, and (central ray penetration thickness is minimum, and both sides become big；The pipeline being relatively large in diameter Then difference very little, the bigger difference of caliber is smaller).If, test block is in strip and is positioned over (the corresponding pipeline of B points in the middle of pipeline Position) carry out transillumination and measure be pipeline marginal position when, then due to actual thickness that the ray of pipe centerline both sides is penetrated Degree becomes larger and (is more than B see Fig. 9, A and C penetration thickness), then gray scale can be caused to taper into；In the presence of such grey scale change When, the thickness and flaw height of A and C points can not be just measured with the slope test block of B points position.

, then can be with if semicircle tight (weld seam on the right of, see Figure 10) beside examined workpiece weld seam is made in test block Ensure the measurement position of whole weld seam scope (projection) has the test block slope gray scale axially in parallel with pipeline to carry out along the y-axis direction Contrast, it is to avoid gamma error caused by thickness change.

When ray is aimed downwardly from the top in picture, digital radial flat receiver generation two dimensional image.In image On, when being drawn a straight line through slope test block and defective locations parallelpiped axial direction, computer can show this line Continuous gray scale change curve, is shown in Figure 12 signals (figure and plate welding before detect that picture is just the same)；Because test block is Section is semicircle, so the grey scale curve avoids pipeline center and the edge when (synchroballistic) ray penetrates small diameter tube The larger influence brought of difference in thickness.Ensuing detecting step and computational methods with discuss before it is identical.

4th, for the detection of integument internal material, an integument can be removed and place test block shooting, then with identical Condition shoot with condition integument.Again the defective locations of test block image cut to the response for the image that should actually detect, The method for reusing discussion same as above is measured.

Discussion, experiment more than are drawn a conclusion：

The present invention uses without gradient fixed slope (slope and thickness can make according to detection demand), makes full use of numeral to penetrate Line DR digitlization feature, material thickness, flaw height absolute value are measured with to gray scale ratio method.Its advantage is summarized as follows：

It this method reduce foregoing description detection mode, the error that measurement accuracy is brought

Avoid the influence (e.g., weld reinforcement out-of-flatness) of field condition

Reduce the quantity of live test block (test block can substitute the thickness test block of plurality of specifications)

Measurement result is more accurate, it is to avoid the potential safety hazard that erroneous judgement is brought

Detection efficiency is substantially increased, is exemplified below：It is existing according to the NB47013 examination criterias of in April, 2015 newest promulgation During the tube welded seam scanning of field, the thickness of test block is equal with the reinforcement of weld seam；But the reinforcement of the weld seam at scene is practised with personal welding There is larger difference in used, weld seam environment etc..Like this, the reinforcement of each weld seam is required to measure actual height, and manufactures The test block of respective thickness；If using the slope test block of certain scope, these steps can be saved.

This method can be quick, feasible accurate survey flaw height, material thickness, solve using conventional method and having a competition The problems of block detection are a kind of innovation, feasible ray detection method.

1st, the test block with slope can be divided into flat-type detection bar shaped test block, the semicircle test block of small pipeline class according to detection shape (test block of Large Diameter Pipeline flat board), anisotropic approach test block (the transillumination condition that simulated defect position is needed when special shape, condition), root It can be divided into the detection of weld reinforcement position, mother metal thickness detection (corroding thinning, internal porosity etc.) according to detection requirement.Use this method Thickness, the thickness of defective locations of optional position can be more accurately measured, the height of defect is obtained after subtracting each other, before solving Polymorphic structure (the be unfit to do test block, measurement accuracy poor) problem, such as aircraft blade interior spilehole being not easily solved.

2nd, this method makes full use of computer technology, can for the detection of integument internal material (such as ammonia refrigeration pipeline) Test block shooting is placed to remove an integument, then the integument with condition is shot with identical condition.Again test block image The defective locations of the response for the image that should actually detect are clipped to, the method for reusing discussion same as above is measured.

Claims (2)

1. Prospect of Digital-Radiography accurately detects the defect of material and the device of thickness, it is characterised in that：

Including the test block with fixed slope, being positioned on detected material, when field of radiation from top to bottom is also cross tested When workpiece and test block with fixed slope, flat board is received by digital radial and receives the ray after decay, by data display Cell translation is managed into two dimensional image；

For flat board weld seam detection, the test block with fixed slope is placed on beside examined workpiece；The test block is that section is right angle ladder The test block of shape, wherein right-angle side horizontal positioned and workpiece are on a horizontal plane；

For small diameter tube detection, with the band slope test block that section is semi-circular shape, the section of the test block axial direction is semicircular ring Shape, the section of circumferential direction is right-angled trapezium；Section is equal to the external diameter of small diameter tube for the internal diameter with slope test block of semi-circular shape, Test block tight is placed on beside weld seam outside examined workpiece.

2. the method for application device as claimed in claim 1, it is characterised in that：The known test block with fixed slope be positioned over by Detect on material, detected using digital radial, obtain two dimensional image and carry out gray scale inquiry, find and defective locations gray scale phase Deng the position of slope test block, so as to calculate the thickness of the point according to the slope of test block；

On 2d, through the test block with fixed slope and defective locations parallel to straight line is streaked when, computer meeting The grey scale change figure of this line is shown, weld reinforcement position gray scale is minimum, maximum through gray scale during defective locations, penetrates slope The X-ray energy loss of test block part changes with the change of thickness；The test block of fixed slope hereinafter referred to as test block；

L is the projected length of test block, and the physical length of test block is L0；By computer find in test block and weld reinforcement at gray scale Equal position, L1 length is calculated by it in the projection of length coordinate；Equally, find in test block and weld defect gray scale Equal position, L2 length is calculated by projection；It is specific as follows：

H：Test block has the height of slope portion, it is known that amount

The relative altitude H1 of weld reinforcement position gray scale can be calculated by formula：

H1=(H/L0) * L1* (L0/L) draw the height of weld reinforcement

The thickness of the nominal wall thickness of minimum constructive height+pipeline of H1+ test blocks=reinforcement position；

Calculate the relative altitude H2 of gray scale at weld defect：

H2=(H/L0) * L2* (L0/L)

Both subtract each other the height for obtaining defective locations：Flaw height=H1-H2.