KR101919027B1 - A method for inspecting the welding part - Google Patents

A method for inspecting the welding part Download PDF

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Publication number
KR101919027B1
KR101919027B1 KR1020180032941A KR20180032941A KR101919027B1 KR 101919027 B1 KR101919027 B1 KR 101919027B1 KR 1020180032941 A KR1020180032941 A KR 1020180032941A KR 20180032941 A KR20180032941 A KR 20180032941A KR 101919027 B1 KR101919027 B1 KR 101919027B1
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KR
South Korea
Prior art keywords
ultrasonic inspection
step
phased array
inspection system
previous stage
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KR1020180032941A
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Korean (ko)
Inventor
임성진
차현진
양현석
이영재
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대한검사기술(주)
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Priority to KR1020180032941A priority Critical patent/KR101919027B1/en
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04Analysing solids
    • G01N29/041Analysing solids on the surface of the material, e.g. using Lamb, Rayleigh or shear waves
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04Analysing solids
    • G01N29/06Visualisation of the interior, e.g. acoustic microscopy
    • G01N29/0654Imaging
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22Details, e.g. general constructional or apparatus details
    • G01N29/26Arrangements for orientation or scanning by relative movement of the head and the sensor
    • G01N29/262Arrangements for orientation or scanning by relative movement of the head and the sensor by electronic orientation or focusing, e.g. with phased arrays

Abstract

The present invention relates to an automatic ultrasonic inspection method using a phased array technique for a 9% Ni butt weld in an LNG storage tank. The ultrasonic inspection method of the butt weld according to the present invention comprises: 1) selecting an ultrasonic inspection system; 2) calibrating the ultrasound inspection system selected in the preceding stage so as to fit the butt weld portion of the test member; 3) performing automatic ultrasonic inspection using a phased array technique on the butt welded portion to be inspected using the ultrasonic inspection system calibrated in the previous stage; 4) analyzing and evaluating the signal obtained by the inspection in the previous stage.

Description

{METHOD FOR INSPECTING THE WELDING PART} of 9% Ni steel butt weld

The present invention relates to an ultrasonic inspection method, and more particularly, to an automatic ultrasonic inspection method using a phased array technique for a 9% Ni butt weld in an LNG storage tank.

In the butt weld with backplate, there is a structure that generates a signal similar to weld defect. Therefore, for a butt weld, the presence of defects is determined by using a square probe that generates an ultrasonic signal toward a defective area with a probe including one oscillator having a certain angle, that is, 45 degrees, 60 degrees, and 70 degrees.

At this time, the position and size of the defect are determined based on the time measured by the signal reflected from the defect and the size of the signal appearing on the display unit.

However, in the butt welded part where the back plate exists, the signal generated due to the structure of the weld surface and the signal generated by the welded joint appear in the display part equally. In other words, the signal generated by the structure of the butt weld surface and the signal generated due to the weld defect are the same in the probe including one vibrator, which makes it difficult to accurately locate the weld defect region.

In addition, the welds of 9% Ni steel are anisotropic coarse grained structure, and because of its characteristics, scattering and attenuation of ultrasonic waves are severe, so it is impossible to test with general ultrasonic inspection method.

An object of the present invention is to provide an automatic ultrasonic inspection method capable of overcoming the scattering and damping effect of ultrasonic waves and deducing quantitative and qualitative inspection results by applying a phased array technique to 9% Ni steel butt welds .

According to another aspect of the present invention, there is provided an ultrasonic inspection method for a butt weld according to the present invention, including: 1) selecting an ultrasonic inspection system; 2) calibrating the ultrasound inspection system selected in the preceding stage so as to fit the butt weld portion of the test member; 3) performing automatic ultrasonic inspection using a phased array technique on the butt welded portion to be inspected using the ultrasonic inspection system calibrated in the previous stage; 4) analyzing and evaluating the signal obtained by the inspection in the previous stage.

In the present invention, the ultrasonic inspection system may include an air compression scanner including an encoder suitable for anisotropic coarse grain boundary inspection, a phased array ultrasonic inspection apparatus, a phased array transducer,

Preferably, the phased array ultrasound diagnostic apparatus includes a display unit capable of generating and storing a sectorial scan image and A, B, and C-scan images, and displaying the stored image in real time.

In the present invention, the step 2) may include the steps of: a) preparing a basic calibration test piece and a contrast calibration test piece; and b) calibrating the ultrasonic inspection system using the basic calibration test piece and the contrast calibration test piece.

In the present invention, the step 3) may include the steps of: c) inspecting and preparing a surface state of the test member; d) setting a scan plan reflecting the selected destination information; e) selecting a circle having a nominal refraction angle that supports the sweep range of the set scan plan, and setting a gate in the range; f) scanning the inspection member using the medium set in the previous step and acquiring data;

In the present invention, step (4) may further include: g) determining whether the data obtained in the previous step is a defect signal or a geometric shape signal for an indication of 40% or more of the acceptance reference length; h) measuring a defect size for an indication determined to be a defect signal in the previous stage; i) classifying the defects using the defect size information obtained in the previous stage, and grouping the multiple defects; j) a step of determining an adhesion to the irradiated defect;

According to the ultrasonic inspection method of the butt weld portion of 9% Ni steel of the present invention, it is possible to detect defects accurately by applying ultrasonic inspection to the butt weld portion which is difficult to accurately locate the weld defect portion, .

1 is a flowchart illustrating a process of an ultrasonic inspection method according to an embodiment of the present invention.
2 and 3 are drawings and photographs showing a basic calibration test piece according to an embodiment of the present invention.
FIGS. 4 to 10 are drawings and photographs showing contrast correction test pieces according to an embodiment of the present invention.
11 and 12 show examples of phased array transducers.
13 and 14 are diagrams showing examples of a scan type using the phased array transducer.
15 and 16 are diagrams showing a calibration process of a phased array probe according to an embodiment of the present invention.

Hereinafter, a specific embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The ultrasonic inspection method of the butt weld according to the present embodiment starts with the step of selecting an appropriate ultrasonic inspection system (S100) as shown in FIG. The ultrasonic inspection system employed in this step S100 preferably includes a phased array ultrasonic inspection equipment including an encoder, a phased array transducer, and a ground.

Specifically, the phased array ultrasound diagnostic apparatus preferably includes a display unit capable of generating and storing a sectorial scan image and A, B, and C-scan images, and displaying the stored image in real time. That is, the ultrasonic inspection system according to the present embodiment should be capable of generating a sectorial scan that can be stored and retrieved at any time, and should be able to be displayed on the display unit screen.

In addition, the S-scan image must be visible in real-time during the scan in order to obtain the correct acquisition data. The S-scan image may include a signal amplification value and defect depth information according to the refraction angle of the ultrasound beam.

Next, the phased array transducer preferably uses a longitudinal wave, a transverse wave, a creeping wave, a round trip tandem, and a transverse crack detection technique to inspect both the welded portion and the heat affected portion of the base material.

Next, as shown in FIG. 2, the ultrasonic inspection system selected in the previous step S100 is corrected (S200) so as to be suitable for the butt weld portion of the inspection member. That is, in this step S200, ultrasound inspection for the target LNG storage tank 9% Ni butt weld is performed for the ultrasonic inspection system selected in the previous step (S100).

This step S200 is divided into two steps of preparing the basic calibration test piece and the contrast calibration test piece S210 and calibrating the ultrasonic testing system S220 using the same. The basic calibration test piece 10 is used for the probe incident point measurement and the time base calibration. As shown in FIGS. 2 and 3, it is preferable to use a V2 type calibration test piece of 9% Ni range.

The contrast calibration specimen is used for sensitivity calibration. Therefore, the above-mentioned contrast proof test specimens should be welded in the same manner as the actual test specimens. They should have the same material, the same welding improvement and the same welds as the actual test specimens and be welded in the same environment as the actual test specimens. Can not be done.

Such a contrast proofing test piece includes the F type contrast proof test piece 20 as shown in Figs. 4 and 5, the D type contrast proof test piece 30 as shown in Figs. 6 and 7, As shown in FIG. 10, a contrast calibration test piece 40 for Creeping Wave and a contrast calibration test piece 50 for Round Trip Tandem are included.

At this time, as shown in the figure, a square-shaped EDM Notch (42) having a depth of 2 mm, a width of 2 mm, and a length of 30 mm should be machined on the contrast proof test piece. On the other hand, if the comparative test piece 50 for the Round Trip Tandem is to be machined with a flat ball 52 having a diameter of 3.0 mm and a depth of 1 / 3t and a thickness of 2 / 3t in the transverse direction in the direction of the welding axis, It should be located in the welding center line.

Next, the ultrasonic inspection system is calibrated using the prepared basic calibration test piece and contrast calibration test piece. This calibration process begins with checking whether each element of the phased array probe is operating normally, verifying the integrity of the ultrasonic inspection equipment, and time-base linearity calibration.

Then, the ultrasonic inspection range is set so that the entire welding portion and the base material heat affected portion of the object to be inspected are included in the inspection region, and the minimum screen range setting depends on the wedge of the phased array transducer. At this time, the phased array transducer may employ various types, as shown in Figs. 11 and 12, so that a wedge is also selected.

Then, as shown in FIGS. 13 and 14, a scan type is selected during a linear scan or a sectorial scan.

On the other hand, as shown in FIG. 15, the phased array transducer 60 is arranged in the basic calibration test piece 10, the gate A is adjusted to a signal of a radius 50 and the gate B is adjusted to a signal of a radius of 100, Calibration can be performed, and the beam width can be corrected while moving the probe 60 according to the guideline as shown in Fig.

Next, as shown in FIG. 1, a step S300 of performing an automatic ultrasonic inspection using a phased array technique is performed on the butt welded portion to be inspected using the ultrasonic inspection system calibrated in the previous stage (S200). In this embodiment, the step S300 is preferably divided into four small steps, and the temperature difference between the calibration test piece and the actual test member is preferably within 10 degrees.

First, a step S310 of checking and preparing the surface state of the inspection member is performed. Removes foreign matter such as welding spatter, scale, rust, dust, etc. existing on the surface of the member to be inspected and removes it if it has roughness that would interfere with free movement of the probe or transmission and reception of ultrasonic waves.

Then, in step S320, a scan plan is set reflecting the selected map information. The scan plan is established by setting an appropriate refraction angle with respect to the improvement angle of the welded portion to be inspected. Then, the selected wedge information is reflected and set.

Then, a circle having a nominal refraction angle that supports the sweep range of the set scan plan is selected, and a step S330 of setting a gate in the corresponding range is performed. In order to inspect the entire volume of the welded portion of the object to be inspected and the heat affected portion of the base material, a wedge having a nominal refraction angle that supports the sweep range of the scan plan is selected and a gate is set.

Then, the vertical and horizontal welds including the T-cross weld are scanned using a sanitary alignment technique (S340). The bottom of the first stage shell and the top 200mm of the 11st shell can not install the scanner, so MUT is performed instead of AUT. The T-cross welds are further subjected to bead cap flush grinding at 300 mm intervals in the vertical and horizontal directions at the intersection of the welds to ensure dryness. Data is acquired through such a scanning process.

Next, as shown in Fig. 1, a step S400 of analyzing and evaluating the signal obtained by the inspection in the previous step S300 is performed. In this step S400, it is determined whether or not a defect signal or a geometric shape signal is present for instructions indicating 40% or more of the acceptance reference length in the data obtained in the previous step S300 or for instructions exceeding 50% of the reference level (S410).

Then, a defect size is measured for an instruction determined to be a defect signal in the previous stage S410, defect classification is performed using the obtained defect size information, and grouping of multiple defects is performed (S420).

And finalization is made in a small step (S430) in which an adhesion is finally determined for the defect examined.

10: Basic calibration test piece 20: F type calibration test piece
30: D type contrast test piece 40: Creeping wave contrast test piece
50: Correction test specimen for Round Trip Tandem
60: Phased array transducer

Claims (5)

1) selecting an ultrasound inspection system;
2) calibrating the ultrasound inspection system selected in the preceding stage so as to fit the butt weld portion of the test member;
3) performing automatic ultrasonic inspection using a phased array technique on the butt welded portion to be inspected using the ultrasonic inspection system calibrated in the previous stage;
4) analyzing and evaluating a signal obtained by the inspection in the previous stage,
The ultrasonic inspection system includes a phased array ultrasonic inspection apparatus including an encoder, a longitudinal wave, a transverse wave and a creeping wave, a round trip tandem, a phased array transducer capable of traverse transverse cracking, And a display unit for displaying and storing the stored image in real time,
The step (2)
a) Contrast calibration test specimens including standard calibration specimens, F type calibration specimen (20), D type contrast specimen (30), contrast calibration specimen for Creeping Wave (40) and contrast specimen for round trip tandem ;
and b) calibrating the ultrasonic inspection system using the basic calibration test piece and the contrast calibration test pieces. The ultrasonic inspection method of the butt welding part of claim 1,
delete
delete
2. The method of claim 1, wherein step (3)
c) inspecting and preparing the surface condition of the inspection member;
d) setting a scan plan reflecting the selected destination information;
e) selecting a circle having a nominal refraction angle that supports the sweep range of the set scan plan, and setting a gate in the range;
f) scanning the inspection member using the medium set in the previous step and acquiring data; and performing ultrasonic inspection of the butt weld portion.
5. The method of claim 4, wherein step (4)
g) determining whether a defect signal or geometric shape signal is indicative of an indication of 40% or more of the acceptance reference length in the data obtained in the previous stage;
h) measuring a defect size for an indication determined to be a defect signal in the previous stage;
i) classifying the defects using the defect size information obtained in the previous stage, and grouping the multiple defects;
and j) a step of determining adhesion to the irradiated defects; and a small step of ultrasonic inspection of the butt weld.
KR1020180032941A 2018-03-21 2018-03-21 A method for inspecting the welding part KR101919027B1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101478465B1 (en) * 2013-10-22 2014-12-31 주식회사 디섹 Mechanized Ultrasonic Testing Method for Curved Pipe Welding Zone
JP2016031310A (en) * 2014-07-29 2016-03-07 株式会社東芝 Ultrasonic flaw detection method and ultrasonic flaw detection apparatus
US20160084802A1 (en) 2014-09-19 2016-03-24 King Fahd University Of Petroleum And Minerals Process for determining weld quality using flexural characteristics

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101478465B1 (en) * 2013-10-22 2014-12-31 주식회사 디섹 Mechanized Ultrasonic Testing Method for Curved Pipe Welding Zone
JP2016031310A (en) * 2014-07-29 2016-03-07 株式会社東芝 Ultrasonic flaw detection method and ultrasonic flaw detection apparatus
US20160084802A1 (en) 2014-09-19 2016-03-24 King Fahd University Of Petroleum And Minerals Process for determining weld quality using flexural characteristics

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