Analysis on Ultrasonic Flaw Detection Technology of Welded Steel Pipe

Analysis on ultrasonic flaw detection technology of welded steel pipe.
1, ultrasonic testing
Ultrasonic testing is one of the non-destructive testing methods, non-destructive testing is not under the premise of damage to the workpiece macroscopical defects or measure the characteristics of various technical methods collectively. Dyed steel pipe conventional non-destructive testing methods are:
Ultrasonic Testing (Radar); Radiographic Testing (abbreviated RT); Magnetic particle testing (abbreviated MT); Penetrant testing Penetrant Testing (abbreviated PT); Eddy Current testing (abbreviated ET);
2, ultrasonic flaw detector
The use of ultrasonic testing methods to detect the instrument called ultrasonic flaw detector. The principle is that when the ultrasonic wave propagates in the tested material, the acoustic characteristics of the material and the change of the internal structure have a certain influence on the propagation of the ultrasonic wave. Through the detection of the degree and condition of the ultrasonic wave, the technique of understanding the material performance and structure change Called ultrasonic testing. Ultrasonic testing methods are usually penetrating, pulse reflection, tandem and other ultrasonic testing is the use of ultrasound can penetrate the depth of metal materials, and from one section into another section, the reflection of the characteristics of the interface edge to check Part of the defect of the method, when the ultrasonic beam from the surface of the parts from the probe to the inside of the metal, encountered defects and parts of the bottom of the surface were reflected waves, the formation of pulse waveform on the screen, according to the pulse waveform to determine the defect location and size.
Non - destructive testing of internal defects of materials using thick - walled steel tubes. Now widely used is to observe the sound pulse in the material reflection of the ultrasonic pulse reflection method, in addition to observation through the material after the incident sound amplitude changes in the penetration method. Commonly used frequency between 0.5 ~ 5MHz. Commonly used test instrument for the A-type display pulse reflection ultrasonic flaw detector.
According to the presence or absence of the reflected signal on the oscilloscope screen, the time interval of the reflected signal and the incident signal, the height of the reflected signal can determine the presence or absence of the reflecting surface, its position and relative size. The basic structure and principle of the instrument are shown in Fig.
Ultrasound in the media when there are a variety of wave propagation, the most commonly used in the test for the longitudinal wave, shear wave, surface wave and plate wave. It can detect the defects such as inclusions, cracks, shrinkage, white spots and delamination in the parts of metal ingot, billet, plate, large forging and shape, which can be used to detect the defects in the pipe. And the surface cracks can be detected on the surface of a simple surface defects; with the plate wave can be detected in the thin plate of the sheet; defect.
In the A-type flaw detector developed on the basis of the B-type, C-type flaw detector can be obtained in different directions of the signal surface can also be B-type, C-type display combination to get the material of the internal reflection of the three-dimensional display The
Each of these flaw detectors utilizes pulsed electrical signals to energize piezoelectric transducers to emit ultrasound, but eddy current acoustic transducers can also be used to test conductive materials.
The transducing process of this transducer is carried out on the surface of the workpiece, without contact with the material, without the need for a coupling agent, to test the surface roughness and temperature up to 500 ℃ above the metal material, spiral steel pipe in the metallurgical industry More.
Ultrasound is propagated in the material, and the strength is attenuated due to absorption and scattering. Therefore, it is possible to measure the attenuation of the alloy material in a furnace such as a vacuum furnace. It is possible to know the uniformity of the material.
Pulse reflection type ultrasonic method compared with other non-destructive testing methods
The main advantages are:
① penetrating ability, detection depth of up to several meters;
② high sensitivity, can be found with about a few tenths of a diameter of the air gap reflectivity equivalent of the reflector;
③ in determining the internal reflector of the bit direction, size, shape and nature of the more accurate;
④ only from one side of the object to be tested;
⑤ can immediately provide defect test results;
⑥ safe operation, equipment, light.

Hunan Great Steel Pipe Co.,Ltd is a world-class production and service provider of submerged arc straight seam welded pipe as the first subsidiary of Shinestar Group. Hunan Great Steel Pipe Co.,Ltd pays more attention to in the pipeline engineering research areas as a pioneer of China Petroleum Pipeline & Gas Pipeline Science Research Institute, Such as: the use of oil and gas pipelines, pipe welding technology innovation, high-end plumbing materials research and development, as well as special tools technological innovation pipeline construction, pipeline corrosion protection science and technology research, science and technology research pipeline non-destructive testing, pipeline quality assessment, and research pipeline standards and so on. In the future, we will try to use new technology to create new business value and to contribute to research and product development for the pipeline. Our main products include: carbon steel seamless pipe, welded steel pipe, stainless steel pipe, coating steel pipe, which is variety types and full range specifications, moreover, strictly in accordance with international standards, like: ISO certification, CE certification. At the same time, we are able to offer value-added steel services, including: hot dip galvanized, anti-corrosion treatment, pipe cutting, or other customized services.
Hunan great steel pipe co.,ltd: http://www.great-pipe.com/
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