Power plant metal machinery steel nondestructive testing

The power plant factory ship metal machinery steel nondestructive testing @
With the development of industry, large diameter thick wall pressure equipment is increasing, the traditional X-ray detection have been unable to meet the demand of welding joint detection, there is an urgent need for a new detection method to replace the. After decades of research and application, TOFD detection technology has replaced ray detection in many fields. Detection of TOFD in the domestic first used in West to east gas pipeline project, after application in the Three Gorges hydropower station, Burma hydropower station project, obtains the consistent high praise. Now TOFD detection has been widely used in petrochemical, electric power, bridges, special equipment manufacturing, installation and maintenance project.

Two, the relevant standards
TSG R0004-2009 "fixed pressure vessel safety technology supervision regulation" provisions of article 4.5.3 shall use the "ray detection and ultrasonic inspection of pressure vessel butt weld joints, ultrasonic testing including TOFD ultrasonic testing (TOFD)". This clause to the pressure vessel manufacturing, installation (renovation, maintenance) process using TOFD detection technology provides the basis for the substitution of ray detection. TSG G0001-2012 "boiler safety supervision regulations" provisions of article 4.5.4.2 "when the selection of the ultrasonic Time-of-flight diffraction (TOFD), should be with the pulse echo method (PE) combined detection, detection conclusion comprehensive judgement were conducted by TOFD and the result of the PE method". The national Department of energy released in 2010 NB/T47013.10-2010 "pressure equipment nondestructive testing of tenth parts: TOFD ultrasonic testing". All these indicate that TOFD detection technology and RT, UT, MT, PT, ET, AE and other detection methods, can already carry out inspection according to the relevant laws and regulations standard requirements.
In foreign countries, TOFD has standard including ASTM E2373-2009, ASME VIII Code 2235, CEN ENV 583-6 (2000), BS 7706 (1993) etc..

Three, introduces the technique principle
Diffraction time difference method (TOFD) is a kind of rely on to find from the internal structure (mainly refers to the defect) methods of diffraction energy to get the "corner" and "end" to detect defects.
Four, the technical advantage:
(a) comparison of detection of TOFD and X-ray
1) TOFD detection can detect the thickness range is large (about 12mm ~ 400mm), the plate detection effect is very good, but the ability to penetrate the thick ray is very limited;
2) TOFD detection of defect detection rate is very high (about 82%), X-ray detection detection rate is low (about 60 ~ 66%);
3) TOFD detection to defect depth and its highly accurate measurement, and X-ray detection is not;
4) TOFD detection acquisition is data information, can carry on the multi range analysis of the defects of using software; and ray detection can only get limited information from a negative;
5) TOFD detection has the advantages of simple operation, fast scanning speed, high testing efficiency; and ray detection process is tedious, time-consuming, low efficiency;
6) TOFD detection method for detection of environmental protection, environment, personnel health without any adverse effects; and ray detection will produce ionizing radiation damage;
7) TOFD for the detection of good economic performance, low cost, repeated cost less; and ray detection, high investment, in the work of consumable costs to recur, the comprehensive cost is relatively high.

(b) compared with the conventional ultrasonic detection of TOFD
1) TOFD for the detection of simple and quick operation, a scan can almost cover the entire weld area, fast detection speed, conventional ultrasound to do the zigzag scanning, detection speed is relatively slow;
2) detection of TOFD good reliability, high detection rate, can be found in various types of defects, is not sensitive to the defect. The test results of foreign research institutions indicate that TOFD positive rate of UT is 20% higher than normal;
3) TOFD quantitative detection of high precision, quantitative and positioning of the defects in the vertical direction is very accurate, has much higher accuracy than the conventional ultrasonic testing. Generally, the linear defect or area type defect, quantitative TOFD detecting error less than 1mm. The cracks and lack of fusion defects height measurement error is usually only a few tenths of a millimeter;
4) TOFD detection can identify defects extending to the surface of the shortcomings of its own, highly quantitative, and conventional ultrasound is difficult for highly quantitative;
5) TOFD detected by D, B scan imaging, flaws more intuitive, changes of conventional ultrasound depends on A scan waveform to identify defects, the results by technical level of the detecting personnel and responsibility
A great influence;
6) TOFD detection map discs can be permanently preserved, overcome the characteristics of the simulated ultrasonic flaw detector and a simple digital ultrasonic flaw detector to record the signal ability is poor, can not only record the signal in whole process, long-term preservation of data, but also high-speed mass signal processing;

Five, economic analysis
The use of TOFD detection, can effectively reduce the cost of testing
Business including X-ray, ultrasound, permeability, magnetic, electromagnetic, acoustic emission, TOFD, magnetic flux leakage and spectroscopy, chemical analysis, metallography, hardness and other professional, covering power, petrochemical, metallurgy, shipbuilding, military, bridge, railway, machinery, nuclear industry
Metal test technology of large power plant construction project inspection of metal, power plant maintenance
Large petrochemical equipment maintenance and repair technology
Physical and chemical, metallographic, spectrum analysis technology of metal materials
Nondestructive testing technology of steel structure material and weld
Large shaft, bolt, screw and other parts of ultrasonic and magnetic particle testing technology
The conventional eddy current testing of ferromagnetic and non ferromagnetic heat exchanger tubing and the far field eddy current testing technology
Spherical tank, oil tank, reactor, long tube trailer of acoustic emission testing technology
X ray real time imaging, phased array inspection technology
Power plant high temperature ultrasonic detection technology
Analysis of mechanical performance test and chemical composition
Welding process assessment of welding technology consulting
Ultrasonic B scan imaging technology, C
Nondestructive testing technology of concrete bridge and subway tunnel
Boiler, pressure vessel, pressure pipe and special equipment of X-ray testing, ultrasonic testing, magnetic particle testing, penetrant testing, eddy current testing, acoustic emission and TOFD detection technology

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