JPH0117535B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic flaw detection method for a pipe-through joint, and an object thereof is to easily and accurately detect the position of a welding defect in a pipe-through joint in the wall thickness direction.

Generally, when conducting an ultrasonic flaw detection test on a pipe-penetrating joint at a critical point such as an offshore structure, it is necessary to know the cross-sectional shape of the flaw detection part of the joint, which changes in a complex three-dimensional manner.
It is necessary to accurately understand the propagation path of ultrasonic waves.

Conventionally, there have been methods of creating a reduced specimen of a pipe-through joint to be tested, and actually cutting the specimen to determine the shape of the cut surface, or applying a comb gauge or putty to the outer surface of the joint to determine the shape of the cut surface. A method is used in which the cross-sectional shape of the flaw detection part is created by molding a part of the outer surface of the joint using a comb gauge or putty.
In the former case, it is necessary to make reduced-scale test specimens of many types of joints with different pipe wall thicknesses and outer diameters, which requires a lot of money and time; in the latter case, the obtained cross-sectional shape is inaccurate, The disadvantage is that the location of the welding defect cannot be accurately determined.

This invention has been made with the above-mentioned points in mind, and includes a pipe interpenetration curve formed by the outer surface of the attached pipe of the pipe interpenetration joint and the outer surface of the pipe to which the joint is attached. Create a developed view, draw orthogonal lines perpendicular to tangents at each point on the pipe interpenetration curve on both developed views, and match the pipe interpenetration curve of both developed views with the pipe interpenetration curve. wrap the developed views around the tubes, transfer the orthogonal lines to the surfaces of the tubes to form a spiral that serves as a scanning guide for the probe, and Of the curvature and torsion of the helices of both the pipes, the torsion is ignored and only the curvature is focused on. A first sectional view for each point is created by removing the torsion of both helices at each point by a concentric inner circular arc with a radius smaller by the wall thickness, and the two pipes in each first sectional view are A normal line is added to each cross-sectional view component to create a second cross-sectional view for each point of each of the pipes, and the probe is scanned along each of the spirals to detect the welded portion of the joint. When performing ultrasonic flaw detection and detecting a defect, the beam path length is measured from the flaw detection waveform, and the refraction angle of the ultrasonic wave by the probe is symmetrical to the normal line in the second cross-sectional view at the point where the helix is specified. drawing an ultrasonic propagation path, plotting a defective point along the propagation path at a position within the beam path from the ultrasonic incident point, and detecting a defect in the first cross-sectional view at the point to identify the helix; The incident point of the second sectional view is made to coincide with the point indicating the position of the probe at the time, and both sectional views are superimposed, and the defect in the welded portion is detected from the defect point of the second sectional view. The present invention provides an ultrasonic flaw detection method for a pipe-penetrating joint, which is characterized by determining the position in the wall thickness direction.

Therefore, according to the ultrasonic flaw detection method for a pipe-penetrating joint of the present invention, flaw detection is performed by scanning a probe along a spiral formed on the surfaces of both pipes, and when a defect is detected, By simply superimposing the second cross-sectional view of the point specifying on the first cross-sectional view, it is possible to easily and accurately determine the position in the wall thickness direction of the defect in the welded portion of the pipe-penetrating joint.

Next, the present invention will be described in detail with reference to drawings showing one embodiment thereof.

(Principle) First, before explaining the embodiments, the principle of the present invention will be explained using FIG. 1 and FIG. 2.

In the drawings, reference numeral 1 indicates a first pipe to be attached, which has an outer diameter D and a wall thickness T, and 2 indicates a second pipe, which has an outer diameter d and a wall thickness T, and which is attached to the first tube 1 at an attachment angle δ. tube,
S is a tube interpenetration curve formed by the outer surface of the first tube 1 and the outer surface of the second tube 2, and 3 is a probe.

When conducting an ultrasonic flaw detection test, the direction of ultrasonic wave incidence must be perpendicular to the defect, taking into consideration the directionality of the defect to be detected. Because defects such as defects and slag entrainment have a length in the direction of the weld line, it is necessary to apply ultrasonic waves at right angles to the weld line. , pipe interpenetration curve S which is the welding line
It is necessary to make the ultrasonic wave incident perpendicular to the tangent line at each point. Pipe-penetrating joints are broadly categorized using parameters such as outer diameter ratio d/D and mounting angle δ, and furthermore, wall thickness, outer diameter ratio t/d, and T/
D is subclassified as a parameter.

Now, as shown in Figure 1a, on the pipe interpenetration curve S, the angle when a point on the curve S is projected onto the first plane L perpendicular to the pipe axis of the second pipe 2 is = _P
Assuming a point P expressed as , a point P on the curve S
Set the tangent M at point P, and the second pipe 2 at point P
The angle α of the first angle A between an orthogonal line perpendicular to the tangent line M in the tangential plane and a line K indicating the tube axis in the tangential plane is: The angle α at any point of the pipe interpenetration curve S changes according to the pipe outer diameter ratio d/D, the mounting angle δ, and the angle.

At this time, point P is a point on the outer surface of the second pipe 2, and generally, when one point is set on the outer surface of the pipe, the tangential plane of the pipe at that point is uniquely determined, and this tangential plane Since always includes the generatrix on the outer surface of the tube that passes through the one point, the tangential plane of the second tube 2 at the point P is also uniquely defined, but the tangential plane of the second tube 2 includes a generatrix that passes through the point P. A line K corresponding to the bus line,
Both the tangent M of the curve S at the point P and the curve S are included.

Similarly, the angle β of the second angle B between the orthogonal line perpendicular to the tangent M in the tangential plane of the first tube 1 at point P and the line indicating the tube axis in the tangential plane is: , which, like the angle α of the first angle A, changes with the outside diameter ratio d/D of the pipe, the installation angle δ, and the angle, and the first pipe at a point P perpendicular to the tangent M. The angle γ of the third angle C between the tangent plane of pipe 1 and the tangent plane of second pipe 2 is as follows: γ=cos ^-1 {cosδ・cos・√1−(・
) ² - d/D・sin ² ... Similar to the angles α and β of the first and second angles A and B, the outer diameter ratio d/D of the pipe and the installation angle δ
and changes with angle.

At this time, the tangential plane of the first tube 1 at the point P includes a generatrix N that passes through the point P and is parallel to the tube axis on the outer surface of the first tube 1, and a point Both the curve S and the tangent M at P are included.

In addition, in the formula, d/D is (d-
2t)/D, the direction perpendicular to the tangent at the point of the pipe interpenetration curve formed by the outer surface of the first pipe 1 and the inner surface of the second pipe 2, that is, the second and first The angles α' and β' between the perpendicular lines of the tangent lines in the respective tangential planes of the tubes 2 and 1 and the lines indicating the tube axes of the second tube 2 and the first tube 1 are represented, respectively.

Therefore, when performing flaw detection from the second tube 2 side, the direction of incidence of ultrasonic waves on point P and the line K indicating the tube axis
The angle formed by the angle α is expressed by the above formula.
Inject the ultrasonic wave so that the first
When performing flaw detection from the tube 1 side, the ultrasonic wave should be incident so that the angle between the direction of incidence of the ultrasonic wave at point P and the line indicating the tube axis is the angle β expressed by the above formula. Therefore, the outer diameter ratio of the tube d/D,
Regarding various pipe interpenetration curves with different installation angles δ,
By calculating the angles α, β, α', and β' in advance using the above equations when the angles are changed by predetermined angles, the direction of incidence of the ultrasonic waves can be easily determined.

Next, if we pay attention to the propagation of ultrasonic waves in tubes such as the first and second tubes 1 and 2, we can see that a thin beam of ultrasonic waves is transmitted from the outer surface of the tube at a certain refraction angle λ with respect to the tube axis. When the ultrasonic wave is incident, the propagation path of the ultrasonic wave is schematically shown in Figure 2, and the x-axis and y-axis in the figure are
Ultrasonic waves incident at a refraction angle λ from a point P ₁ on the outer surface of the tube with coordinates x ₁ , y ₁ , z ₁ in a three-dimensional space consisting of the coordinate axes x 1 , y 1 , z 1 have coordinates x ₂ , y ₂ , z ₂ is reflected at point Q ₁ on the inner surface of the tube and points on the outer surface of the tube with coordinates x ₃ , y ₃ , z ₃
Reach R ₁ . Then, the tangential planes of the outer surface and inner surface of the pipe at each point P ₁ , Q ₁ , R ₁ are set to the second to fourth points, respectively.
Let the planes D, E, and F be the angles formed by the second plane D and the third plane E, and the angles formed by the third plane E and the fourth plane F as μ and μ', respectively, and each point P ₁ , Q ₁ , and R When the projection points of ₁ onto the x-y plane and the third plane E are respectively points P ₂ , Q ₂ , R ₂ and points P ₃ , Q ₃ , R ₃ , the formation of the vector OP ₂ → and the x-axis angle and ∠
Let P ₂ OQ ₂ (∠R ₂ OQ ₂ ) be ν and ε, respectively, and point Q ₁
If the intersection of the normal to the third plane E and the outer surface of the tube is a point U with coordinates x ₄ , y ₄ , z ₄ , vector P ₁ Q ₁ →,
Q ₁ R ₁ → and Q ₁ U → are all in the fifth plane G,
The fifth plane G and the third plane E are orthogonal to each other, and the fifth plane G
∠P ₁ Q ₁ U=∠R ₁ Q ₁ U and μ=μ′=
ε, and the line of intersection between the fifth plane G and the third plane E is x
Assuming that there is a slope of tanξ with respect to the −y plane,
The vectors OP ₁ →, OQ ₁ →, OR ₁ → are respectively OP ₁ →=(x ₁ , y ₁ , z ₁ )=(d/2.cosν, d/2・si
nν, z ₁ )... OQ → ₁ = (x ₂ , y ₂ , z ₂ ) = ((d/2-t)・cos(ε+ν), (d/2-
t)・sin (ε+ν), ltanξ+z ₁ )... OR→ ₁ = (x ₃ , y ₃ , z ₃ ) = (d/2・cos (2ε+ν), d/2・sin (2ε+
ν), 2ltanξ+z ₁ )..., where l=|P ₃ Q ₃ →|=|Q ₃ R ₃ →|, and from the ~ formula, OU→=(x ₄ , y ₄ , z ₄ ) = ( d/2・cos(ε+ν), d/2・sin(ε+ν)
, ltanξ+z ₁ )..., and the direction cosines of the vectors P ₁ Q ₁ → and Q ₁ R ₁ → with respect to the x and y axes are different, and the direction cosines with respect to the z axis are the same, and the angle from the outer surface of the tube to the tube axis is The incident point of the ultrasonic wave incident with
If you connect the projection point of the reflection point onto the outside surface and the point where it reaches the outside surface with the outside surface of the tube, the connected line will draw a spiral.

In other words, when an ultrasonic wave is incident along a helix set on the outer surface of a tube, the ultrasonic wave reflected from the inner surface of the tube will reach the helix, and one point on the helix will be reflected. Assuming an imaginary line perpendicular to the spiral, if an ultrasonic wave is incident along the helix, the incident ultrasonic wave will always be orthogonal to the imaginary line.

Therefore, from the results shown in FIG.
In order to make the light enter from the second pipe 2 side, the second pipe 2 at the point P
The advance angle ( It is sufficient to scan the probe back and forth along a spiral of 90°-α), and when the probe is incident from the first tube 1 side, a line perpendicular to the tangent M in the tangential plane of the first tube 1 at point P and Adjust the advance angle (90° - β) so that the angle β of the second angle B with the line indicating the pipe axis of the first pipe 1 is equal to the value calculated by the above formula.
The probe can be scanned back and forth along the spiral.

(Example) Next, examples will be described.

Now, in order to actually form the above-mentioned spiral, a developed view of both pipes 1 and 2 including the pipe interpenetration curve S is created, and the lines are perpendicular to the tangents at each point at each predetermined angle of the pipe interpenetration curve S. Draw orthogonal lines, wrap both developed views around both pipes 1 and 2, matching the pipe interpenetration curves, and transfer each drawn orthogonal line to the surface of both pipes 1 and 2 by marking, etc. This forms a spiral that serves as a scanning guide for the probe.

At this time, the angles formed by each helix at each point and the generatrix of both tubes 1 and 2 passing through each point are α and β, and the advancing angle of each helix of both tubes 1 and 2 is (90° − α ), (90°−β).

For example, the tubes 1 and 2 are arranged in the wall thickness direction so as to include both helices of the advancing angles (90°-α) and (90°-β) of the tubes 1 and 2 at the point P of the tube interpenetration curve S. Of the curvature and torsion that determine the helix of the cut surface of each tube 1 and 2 when cut, the torsion is ignored and only the curvature is focused, and a computer or the like is used to determine the point P.
The radial direction is taken in the direction orthogonal to the tangent plane of each tube 1, 2, and an outer arc is drawn with the radius being the reciprocal of the curvature of each spiral, and the outer arc is drawn by the wall thickness of both tubes 1, 2. A first sectional view in which an inner arc is drawn with a radius smaller than the radius, the twist of both helices at point P is removed, the wall thickness is constant, and the cutting angle of the end on the second pipe 2 side is made the same as the beveling angle. At the same time, obtain first cross-sectional views at each predetermined angle ranging from 0° to 360°, understand in advance the cross-sectional shapes when the angles are different, and create cross-sectional views of both pipes 1 and 2 in each first cross-sectional view. The second pipe for each predetermined angle of the first pipe 1 and the second pipe 2 with the normal added to the component.
Create a cross-sectional view of each.

At this time, the outer diameter ratio of the tube d/D=0.797, the mounting angle δ=45°, the wall thickness outer diameter ratio of the first tube 1 T/D=
0.049, and the wall thickness outer diameter ratio t/d of the second pipe 2 is 0.062, for example, the first cross-sectional view as shown in FIG. A second sectional view of the second tube 2 as shown in FIG. 4 is obtained. Further, from the obtained first cross-sectional view, it is possible to select the refraction angle λ of the ultrasonic wave to be incident on the flaw detection point at a predetermined angle and α. For example, each first cross-sectional view as shown in FIG. If obtained, for the flaw detection point of = 0° and α = 0°, there will be a region where ultrasonic waves cannot be incident at λ = 45° either by the direct method or the single reflection method, so λ It is easy to see that the ultrasonic wave should be incident at = 70° and using the single reflection method, and at = 90° and α = 46°, the ultrasonic wave should be incident at λ = 45° and using the single reflection method, It can be easily seen that when α=180° and α=0°, the refraction angle λ may be either λ=45° or λ=70° if the single reflection method is used. In addition, in FIG. 5, the mark ◯ indicates a defect, and the mark ▽ indicates the probe approach limit position.

Furthermore, in order to deal with the difference in the position in the wall thickness direction where flaws are to be detected, when flaws are detected from the second tube 2 side, the tube mutual contact formed by the outer surface of the first tube 1 and the inner surface of the second tube 2 is The angle α' between the line in the tangential plane orthogonal to the tangent at the point of the curve and the tube axis of the second tube 2, and the propagation path of the ultrasonic wave as the progress of the spiral on the inner surface of the second tube 2. Calculate the swing angle of the probe (α″-α) from the angle α″ when expressed as an angle, and also calculate the swing angle in the same manner as above when performing flaw detection from the first pipe 1 side. do.

When performing flaw detection from the second tube 2 side, the probe 3 is moved along the spiral of the advance angle α of the outer surface of the second tube 2, as shown in FIG. −α) By scanning back and forth while swinging the head at a time, ultrasonic waves with a predetermined refraction angle λ are accurately and precisely incident on each point on the line in the wall thickness direction including point P of the pipe interpenetration curve S. Can be done.

By the way, when a defect is detected, the beam path from the flaw detection waveform to the defect echo is measured, and the propagation path of the ultrasonic wave with a refraction angle symmetrical to the normal is plotted in the second cross-sectional view at the angle that specifies the helix. At the same time, a defect point is plotted along the propagation path at a position within the beam path from the point of incidence of the ultrasonic wave, and at the point indicating the position of the probe 3 at the time of defect detection in the first cross-sectional view at the same angle, By matching the incident points of the ultrasonic waves in the second cross-sectional view and superimposing the second cross-sectional view on the first cross-sectional view, it is possible to determine where the defective point in the second cross-sectional view is located in the first cross-sectional view. , the position of the defect in the pipe interpenetration curve in the wall thickness direction can be determined from both cross-sectional views, and these operations are repeated for angles ranging from 0° to 360°, making it easy to detect flaws in the welded part of the pipe interpenetration joint. It will be held in

That is, for example, the wall thickness outer diameter ratio T/
D=0.084, wall thickness outer diameter ratio t/d= of the second pipe 2
0.0341, when testing a pipe-penetrating joint with an installation angle δ = 30°, when a defect is detected at an angle = 120°, the first cross-sectional view at = 120° shown by the dashed-dotted line in Fig. 7. Point V indicating the position of the probe at the time of detection including a defect is plotted on the top, and 2 in the same figure is plotted.
On the second cross-sectional view of the second tube 2 at =120° indicated by the dotted chain line, the propagation path of the ultrasonic wave with a refraction angle of 70° is drawn, and the defect point m is plotted from the beam path.
When the second cross-sectional view is superimposed on the first cross-sectional view so that the incident point W of the ultrasonic wave in the second cross-sectional view coincides with the point V of the first cross-sectional view, the point m on the second cross-sectional view is The position of the defect in the wall thickness direction can be easily determined depending on where the defect is located in the first cross-sectional view.

In addition, when performing flaw detection from the first tube 1 side, the second sectional view of the first tube 1 indicated by the thin solid line in the figure may be superimposed on the first sectional view, as described above.

Therefore, according to the embodiment, by simply superimposing the second cross-sectional view at the angle at which the defect was detected on the first cross-sectional view, it is possible to easily and accurately determine the position in the wall thickness direction of the defect in the welded portion of the pipe-penetrating joint. can be detected.

[Brief explanation of drawings]

The drawings show an embodiment of the ultrasonic flaw detection method for a pipe-penetrating joint according to the present invention, in which Fig. 1a is a front view and Fig. 1b is a front view.
is a left side view of Figure a, and Figure 2 is a diagram schematically showing the propagation path when a thin beam of ultrasonic waves is incident from the outer surface of the tube at a certain refraction angle and at an angle to the tube axis. FIG. 3 is a first sectional view when the angles are different, FIG. 4 is a second sectional view when the angles are different, and FIG. 5 is a diagram showing the ultrasound incident area when the angles and α are different. FIG. 6 is an enlarged cross-sectional view of a part during flaw detection, and FIG. 7 is an explanatory diagram of the operation when detecting a defect position. 1...First tube, 2...Second tube, 3...Probe,
S...Pipe interpenetration curve.

Claims (1)

[Claims] 1. Create a developed view of each of the two pipes including a pipe mutually curved line formed by the outer surface of the attached pipe of the pipe mutually fitting and the outer surface of the pipe to which the joint is attached, and add the pipe mutually Draw orthogonal lines perpendicular to tangent lines at each point on the curve, match the pipe interpenetration curves of both developed views with the pipe interrelated curves, and wrap both developed views around both pipes, and The lines are transferred to the surfaces of the two tubes to form a helix that serves as a scanning guide for the probe on the surfaces of the two tubes, and the torsion ratio is determined among the curvature and torsion of the helices of the two tubes at each point. By ignoring the curvature and focusing only on the curvature, the above-mentioned A first cross-sectional view is created for each point in which the torsion of both helices at each point is removed, and a normal line is added to the cross-sectional view component of each of the two pipes in each first cross-sectional view, and each of the two pipes is A second cross-sectional view is created for each of the above points, and the probe is scanned along each of the helices to conduct ultrasonic flaw detection of the welded part of the joint. When defects are detected, the beam path is determined from the flaw detection waveform. measure,
In the second cross-sectional view at the point specifying the helix, an ultrasound propagation path of the refraction angle of the ultrasound by the probe is drawn symmetrically to the normal line, and
Defect points are plotted along the propagation path at a position within the beam path from the point of incidence of the ultrasonic wave, and the position of the probe at the time of detecting the defect in the first cross-sectional view at the point specifying the helix is indicated. At the point, the second point
A pipe-penetrating joint characterized in that the incidence points of the cross-sectional views are made to coincide, the two cross-sectional views are superimposed, and the position in the wall thickness direction of the defect in the welded portion is determined from the defect point in the second cross-sectional view. Ultrasonic flaw detection method.