17th World Conference on Nondestructive Testing, 25-28 Oct 2008, Shanghai, China

The Advent of Age with Integrated NDT Technology

Junming LIN Eddysun (Xiamen) Electronic CO., LTD., Xiamen, Fujian 361004

Tel: 86-0592-2223833 Fax:86-0592-2237091 Email:Lin_0592@126.com Web:www.eddysun-ndt.com

Abstract:

we are facing a new time, the characteristics of which are information detonation and technical high integration. The development of advanced techniques promotes the progress of every stratification life. NDT technology, relating national economy and livelihood of people, needs developing with the time. Its vitality is based on not only the independent development of every NDT method itself, but also the application of comprehensive method integrating several NDT methods. High temperature, speed and pressure are important symbols of modern developed industry, and nowadays with the request of society on quality and safe application of products enhancing day by day, former single NDT method has more and more problems to tackle. Therefore, it is the tendency to integrate the existing NDT technologies for modern industrial applications.

Keywords: NDT, integrated technology

I．．．． Introduction

A new technology era featured with information explosion and the high integration of technology is coming. The development of high technology promotes the social life of all levels, and the development of electron technology has made great changes in people’s life [1]. For example, mobile phones, instead of playing the single function of being a telephone, have integrated many others such as calendar, alarm clock, mailing, music and videography. From the developing trend of mobile phones, we can see that a highly integrated technology era is on its way [2]. However, in the field of NDT (Non-destructive Testing), many detecting techniques have not been fully integrated to be applied.

NDT is a technology associated with national well-being and the people’s livelihood and has applied into many fields such as electric power, railway, aerospace, petrol and chemical industry, to assure the safe manufacture and the production quality control. However, the application of high-tech in NDT is relatively lag behind, developing not as fast as many leading academic subjects like communication and IT. Unlike the usual technologies, NDT requires high professional ability and rich practical experience of its technicians, for many situations testing can only be done with the technicians’ experience. Therefore, a high quality of NDT technicians is required and such technology mastering is relatively difficult. It will be more convenient for the users if a testing instrument can test materials by using many different methods, it can analyze completely and give a relatively clear diagnostic conclusion. If we integrate many kinds of NDT techniques, analyzing and evaluating the data collected

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and stored through these techniques, working efficiency would be improved and dependence on technicians’ experience would be reduced [3].

II. Necessity for Application of NDT Integrated Technique (Essentiality)

The present NDT technique includes five conventional methods which are ultrasonic,

x-rays, magnetic powder, eddy current, penetrating and some unconventional methods such

as magnetic flux leakage, endoscope and acoustic emission. Every testing technique has its

own basic principles and testing features. For example, ultrasonic testing, one of the widest

used NDT technique, can be used to test many component parts such as metal, non metal, and

composite materials. However, such testing technique has its own limits, for example, the

material has testing dead area; the surface defects can hardly be tested; components with

rough surface have to be pretreated; rough surface components without pretreatment can

hardly be tested well. The x-rays testing also has many disadvantage, for example, high cost,

low sensitivity for planar defects like crack, and harmfulness for people. The advantages of

eddy current are many such as fast speed, not-contact between coil and test piece, no

coupling , but it can only be used to test the defects of surface and the subsurface of electric

conductors, and hardly to test the components in complex shape. It is safe to say that each

testing method has its own advantages and disadvantages, and with different and complex

components to be tested, it is hard to give an overall and total correct judgment and

evaluation of the components’ defect level and its life if relying on a single testing technique.

If we can integrate theses NDT techniques on the base of the complementarities,

integrating many testing methods into one instrument to complete different duties, then the

new integrating technology is undoubtedly a great progress for NDT, and we should realize

this plan by making full use of the present rapid developing science and technology[4]. Like a

patient in need of treatment, from the primitive lack of medicine to buying medicine

according to a prescription, to going to a clinic to see a doctor, and to going to big hospitals

for experts of different expertise in nowadays, components can be tested by the new NDT

technique integrated by different testing techniques.

Because of the limits of a single NDT technique, in many important situations such as in

the test of military aircrafts, civil aircrafts, electric power plant, chemical plant, and atomic

submarine, different testing measures are used simultaneously to improve the quality of

testing. What’s more, the theory of data fusion has been developed in information theory.

However, most NDT instrument suppliers at home and abroad can only supply instrument

with a single testing method, and there is no testing instrument can fulfill all the testing

requirement of customers [5]. The data fusion has to use many different instruments.

NDT integrated technology is a new concept, having no definite definition in present

documents. I think that NDT integrated technology can be defined as a kind of

non-destructive testing technology that has two or more non-destructive testing methods,

integrating software and hardware together, and can do the resources sharing and

comprehensive processing with the test data. It should have three basic features as following.

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Firstly, it’s able to test the same component by using two or more testing methods

simultaneously, and such ability can not below the level with single function. Secondly, it

should have integrative device support facility and can do the resources sharing and

comprehensive processing with the test data (including same-screen display). Thirdly, it is not

a simple integration of many different techniques but can integrate and process the data that

collected through many testing methods and make a unified conclusion.

NDT integrated technology has great influence in the fields of industry, military, and

scientific research. In whatever field, enormous quantities, high speed, good quality and fine

accuracy are the eternal subjects for non-destructive testing. The present testing instruments

are usually playing a single function and with single testing method, which caused

inconvenience for the users. In many situations, some different instruments are needed, for an

instrument with a single function is not able to complete the testing duties, which

undoubtedly increase the cost and time [6]. If the NDT integrated technology which provides

many different testing methods can be achieved, like the present mobile phones that integrate

many technologies, it also can provide many different testing methods, different testing

requirements can be fulfilled in high efficiency and superior quality.

III. The feasibility of NDT integrated technology

The development of Digital Electronic Technique and the wide application of integrated

electronics such as FPGA、ARM、DSP makes it possible to develop NDT integrating

technology products. From the analysis, we know that different testing methods and

instruments, because of their testing basic principles, have different signal extracting and

processing methods. But as electronic instruments, these different testing instruments have

some qualities in common. For example, they have some similar or even the same processing

software and hardware connection in signal generating, data collecting, signal amplifying,

signal display, and data storing and data recording, and if we can fully take advantage of

these common qualities, uniting the key parts of the controlling and amplifying of signal

generating, data acquisition, system software and visualization into an open digital

information processing platform added with the parts which can independently go through

signal generating, receiving, and processing of different testing principles, NDT integrating

technology is achieved.

Take the integration of ultrasonic testing and eddy current testing as an example to

illustrate the forming of the integrating system. The main components and working principles

of ultrasonic testing is showed in fig. 1. A pulse signal generated by the signal generator

changes into a high voltage impulse when coming through drive circuit, and the high voltage

is changed into ultrasonic waves through excitating transmit probe which was sent into the

tested devices. When the ultrasonic waves are returned back and received by the receiving

probe, they are transmitted into electrical signals which, after being pre-amplified, signal

processing, and AD data collected, are sent to the computer system to analyze and display.

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Probe

Pre-amplification

Drive circuit

AD acquisition

Signal generator

Adjustable gain amplification

Phase demodulation

Equalizing filter

Computer processing

Alarm

circuit

Printing Data

administration

Power module

Printing equipment and alarm circuit can be connected.

. Fig.1 Ultrasonic Testing System Diagram Fig. 2 Eddy Current Testing Diagram

The main components and basic working principles of eddy current testing systems are

described in fig.2. A signal with a certain frequency was generated by the signal generator

which is changed into sine wave or pulse wave through excitation probe to produce eddy

current. The returned signal received by the receiving probe, after being pre-amplified, are

processed by phase demodulation and equalizing filter, and signal processed, after being

treated in the gain amplifier and AD data acquisition, is sent to the computer system to

analyze and display. Printing equipment and alarm circuit can be connected with the

instrument.

From the above two figures, we can see that the two testing methods have both mutually

different parts as well as the same parts. They are different in signal converting, extracting,

and processing but the same in signal generating, amplifying, AD acquisition, data storing,

management, recording, alarm, printing, visual display. If we can integrate the two testing

methods into a single instrument, distributing equitably in soft and hard wares to fully utilize

the shared resource by giving a transfer switch, it will bring great convenience for the

customers and more importantly, its centralized management for the testing data is

convenient for users to have a compare and analysis. The present practice has proved that it is

Signal generator

Drive circuit

Probe

Pre-amplification

Signal processing

AD acquisition

Computer

Alarm circuit

Data administration

Printing

Power module

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highly possible to achieve such NDT integrated technology.

IV. The current developing situation of NDT integrated technology.

In overseas, NDT integrated technology has been paid attention upon and has been put

into practical application. All sorts of comprehensive and integrated testing products are

coming into the markets and the two main series are macro-scale online testing system and

the portable integrating instrument. The ultrasonic

plus leakage magnetic NDT system developed by

Bowing International Company in USA is a kind of

online testing system, mainly applying into steel

piping quality detection. This system combines

ultrasonic and magnetic flux leakage techniques,

making full use of their complementarities [7]. At

present, it is a trend that steel piping enterprises tend

to absorb the integrating detecting system to make an

efficient control of the steel piping, but because of its

large volume, according to the definition in section III, such detecting system can only be

called a comprehensive detecting system instead of an integrated detecting instrument.

Another example is TC5700, portable detecting instrument(as showed in fig.5, when

detecting, a computer is needed to assist, AC220V

power supply ) produced by R\D Tech, a

Canadian company, integrating eddy current,

remote field eddy current, magnetic flux leakage

and ultrasonic. This kind of instrument can detect

not only heat exchanger pipe made in any material

but also skelp with revolving ultrasonic probe. What’s more, PowerStation and WorkStation

2000 are two kinds of modular multi-tech

Fig.3 TC5700 pipe testing instrument

a. WorkStation 2000 b.Powerstation

Fig.4 eddy current pluses ultrasonic testing instrument

Fig.5 EEC-96 multi-functional electromagnetic

testing imager

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detecting instruments developed by Olympus Company of US which integrate eddy current and ultrasonic techniques. The instrument includes three parts: basic component, control panel and front modular. By changing the front modular, the user can easily switch between eddy current detecting and ultrasonic detecting, and PowerStation can work with the two techniques simultaneously going on. The new product, MultiScan MS5800 detecting instrument developed by Olympus company is also an integrating instrument, combining eddy current, magnetic flux leakage, remote field eddy current, and ultrasonic detecting[8].

Fig.6 EEC-2008 block diagram

In china, a breakthrough can be seen in integrating eddy current and ultrasonic

techniques and NDT integrated technique. In the mid and late 1990s’, Chinese nonferrous

metals research institute and The Metal Institute of Chinese Academy of Sciences absorbed

two different methods to have online detect on small-bore metal skelp, but the detecting

instruments used were from different factories and not integrated detecting instrument. It is

not until 1996 when EDDYSUN (Xiamen) first developed EEC-96, a multi-function

electromagnetic imager that some features of NDT integrated technology was preliminarily

showed. For the first time in china, multi-frequency eddy current, remote-field eddy current,

prospective multi-frequency, frequency spectrum analysis and eddy current imaging are

integrated into a single instrument (as showed in fig.5 ), and EEC-2000, a new kind of

multi-function detecting instrument integrated electromagnetic and phonic, is a further

exploration in NDT integrated technology.

Signal

generatin

g module

Switcher

Regular eddy current

Magnetic Flux Leakage

Low-frequency

Electronic magnetic field

Ultrasonic testing

Sound impedance

Magnetic memory

Remote-field eddy

Computer

processing

unit

AD

acquisitio

Power

module

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Take EEC-2008 for example which is a detecting instrument integrated with

electromagnetic and phonic. It includes two parts, one is the special module of

multi-detecting-methods, and the other is the common module. The special module

includes conventional eddy current

detecting module, remote-field

eddy current detecting module,

magnetic memory module,

magnetic flux leakage detecting

module, low frequency

electromagnetic field detecting

module, and sound impedance

detecting module, while the

common module includes signal

generating, contact switcher, A/D

switching and collecting, computer

information processing units,

system software, visual display

module, keyboard module, communications interface and power module etc (this kind of

instrument is embed with two-dimensional coordinate card supporting scanning imaging of

many different testing methods ). When EEC-2008 works, the signal generating module,

through transfer switch, selects one or two modules among regular eddy current testing

module, remote-field eddy current testing module, magnetic memory testing module,

magnetic flux leakage testing module, low-frequency testing module, ultrasonic testing

module, or sound impedance detecting module to work with, and the output signal obtained

by the selected module is put to convert by A/D converter, then the converted signal goes to

the computer information processing unit from where it finally is put to the display device.

Because of its modular design, EEC-2008 can be redesigned into a portable instrument if

needed. In the aspect of software operating system, the users can make all-sided analysis

and a comprehensive check with the testing data that got simultaneously and at different

time to get a more complete and reliable testing conclusion. Fig.7 is a display image of

eddy current detecting and leakage magnetic detecting working simultaneously.

It is necessary to point out that integrated technology can not be achieved at the expense

of the performance index of a certain single testing function, and it should be able to do the

exchange testing with the widely used single-functional testing instrument, or it will lose its

use value.

Fig.7. single-screen display of eddy current and leakage magnetic testing

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SMART/EEC-2005 electromagnetic plus ultrasonic integrating instrument has been successively applied to test military aircraft of the Air Force and welded seam testing of the power station. At present, NDT integrated technology is limited into integrating electro magnetic and ultrasonic testing methods, but with the improving of integrated technology, such products will perfect themselves and become more advanced that can test more devices and fulfill more requirements. VI. Conclusion

The era of NDT integrated technology has arrived. It is promising in improving

testing efficiency and in evaluating the reliability, completeness and accuracy of information,

and the benefits it brings are lucrative. NDT technology as a comprehensive application

technology, from Nondestructive Inspection (NDI) to Nondestructive Detecting (NDT) and to

Nondestructive Evaluate (NDE), is developing towards to Automatic Nondestructive

Evaluate (ANDE) and Qualitative Nondestructive Evaluate (QNDE) and the development

requires ceaseless technical innovation [9]. We believe that NDT integrated technology will

bring nondestructive testing technology into a new period, and its emersion will bring more

opportunities as well as challenges for us. In the future, the NDT integrated technology

whose testing result will develop from qualitative to quantitative by keeping perfecting itself,

will integrate into instrument health status evaluation and reproducing techniques to form a

green cycling economy system. We believe that in the near future, NDT integrated

technology will become an important milestone in the development of NDT technology [10].

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Fig. 8 SMART-2005 Portable Electro Magnetic

plus Ultrasonic Testing Instrument

Fig.9 EEC-2005 visual plus eddy current subsystem testing

plane

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