17 pag. 146-154. The Intelligent system of Automatic ... · 20, Mesterul Manole str., Chisinau, R. Moldova, MD-2044; [email protected] ABSTRACT Questions of automatic tracking a

International Conference 2ND International Conference on Innovations, Recent Trends and Challenges

in Mechatronics, Mechanical Engineering and New High-Tech Products Development

MECAHITECH‘10

Bucharest, 23-24 September 2010

146

The Intelligent system of Automatic Tracking

Behind the Welded Seam at the Ultrasonic Testing of Pipes

A. Tkachenko - IC NDT Introscop S.A., 20, Mesterul Manole str., Chisinau, R. Moldova, MD-2044; [email protected]

ABSTRACT

Questions of automatic tracking a welded seam are considered, the way of automatic tracking a welded seam on the acoustic signals received from a zone of a seam and a way of reduction of influence of instability of a corner of input is investigated and offered of ultrasonic fluctuations (USF) in the course of ultrasonic testing (UST) of welded seams of pipes for the main pipelines in a stream of their manufacture are considered, principles of construction intelligent installations of the automated ultrasonic testing (AUST) welded pipes are resulted, described structure and features of acoustic systems and equipment of new installations of the testing.

INTRODUCTION

Results theoretical and experimental researches, microelectronics and computer facilities rapid development was positively reflected in perfection of principles of construction of installations of the AUST of welded pipes in the conditions of their manufacture. On change to bulky analogue systems the new digital technologies, programmed logic matrixes, systems of processing and information display stage by stage take root. Management of work of installations as a part of the automated control systems of technological processes (ACSTP) shops and factories is improved, loading of adjusting parameters, monitoring procedure, formation and delivery of the passport of the testing is programmed. On the same level with circuit and structural perfection principles of construction and adaptation of installations to conditions of the testing and to requirements of norms and standards, creations and introductions of new techniques of the testing develop. Possibility of operative change is realized: Parameters of strobes-impulses, capacities of the generator, rejection criteria depending on position of the acoustic block. Possibility of formation of various types of time adjustment of sensitivity (TAS) and increases of reliability of the control at the expense of statistical processing of signals is received.

Conditions of wide introduction intelligent systems of automatic tracking a welded seam in dynamics of the testing, a rating of a status of acoustic contact are created, opportunities of adaptation new and before the developed ways of increase reliability of results UST, creation of new ways of increase of noise immunity of control devices and automatic adjustment of amplification of channels testing are expanded. TEORETICAL A SUBSTANTIATION OF A WAY OF TRACKING A WELDED SEAM

One of the major conditions of realization of the control of a welded seam automated ultrasonic testing is maintenance of reliable tracking a seam. Provided that the corner of input of ultrasound in metal of a wall of a pipe α = const, work of the



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watching device consists in maintenance at the set level of distance L between the ultrasonic piezoelectric converter (probe) and a seam (0 - point Lo) (figs.1).

Figs.1. Displacement of peak of function Ак (L, α) rather L 0 at change α: Continuous line - nominal position of peak of function,

Dotted and axial - a deviation of peak of function from nominal position.

Cross-section displacement of a seam rather probe in the course of the control lead to a deviation of distance L from parameter Lo, that is there is a difference │∆L│= (Lo - L). As a result watching device directs ПЭП towards reduction of the arisen mismatch and directs │∆L│→ 0. At │∆L│= 0 distance coincidence between a site of metal of a seam and probe installations UST again takes place. By such principle almost all devices of tracking a welded seam work. The set of realizations of systems of tracking a welded seam in the course of the AUST, using various physical principles for measurement and automatic working off of a mismatch │∆L│ [1 - 3] is known. In these systems influence of instability of a corner of input UST in the controllable product arising under the influence of various factors (detritions holders in which it is established probe, and prisms probe, change of temperature of prism probe, geometrical parameters of a pipe, etc.) is not considered.

On figs.2 are displayed sequence of casual values of function of Ак [n ТZ] and of some the valid average values of estimations mк, amplitudes echo-signals Ак from a distant edge of the platen of strengthening of a seam; ТZ - a clock interval of sounding; n = 1, 2, 3, … ∞ - a serial number of clock interval ТZ.; Тint - a time interval in which calculation of average value mк amplitudes echo-signals is made by Ак; l = 1, 2, 3, … ∞ - a serial number Тint. Besides, ∆ (1)Кm - a difference of the first order of

average values mк amplitudes echo-signals Ак in the next time intervals Тint, and ∆ (2)Km - an increment of a difference of average values mк amplitudes echo-signals

Ак .



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Figs.2. Sequence of the valid and average values of amplitudes of function of Ак [nТZ]

At L ≈ Lo = const corner change α leads to displacement of peak of function of

Ак (L,α) concerning the nominal position designated by a continuous line. New optimum position of peak of function is designated by a dotted or axial line, that is value of parameter Lo does not correspond to a condition of coincidence of peak of function of Ак (L,α) with position of a distant edge of the platen of strengthening of a seam. Hence, the tracking device should move probe on a pipe so that the distant edge of the platen of strengthening of a seam has coincided with new peak of function of Ак (L,α), that is was combined with position OL′ or OL ′′ . Slow displacement of peak of function of Ак (L,α) in one or other party rather Lo leads to occurrence of a positive increment of a difference of the first order ∆ (1)Кm

( )∆ (1)К Кl К l+1m m - m= (1)

That is on an input of the device of tracking there is an operating voltage. For definition of a direction of regulation it is necessary to calculate a difference of the second order

( ) ( ) ( )∆ ∆ ∆(2)К int (1)К int (1)К intm l +2 Т m l +1 Т m l +2 Т= − (2)

and at performance of condition ∆ (1)Кm 0≈ coincidence of peak of function of Ак (L,α)

with metal of a distant edge of the platen of strengthening of a seam takes place. Now optimum distance on perimeter of a pipe from inclined probe to a distant edge of the platen of strengthening of a seam equally 0 - OL′ or 0 - OL ′′ . Thus, the tracking device compensates both casual cross-section displacement of a seam, and change of a corner of input USF α. By results of the spent researches the way of automatic tracking a welded seam with the platen of the strengthening [4], raising reliability of the control of a welded seam is offered at instability of a corner of input USF of fluctuations in a controllable product. The system works as follows. In each clock interval of sounding of welded seam ТZ

measurement of amplitudes of set echo-signals Ак from a distant edge of the platen of strengthening is made. In a certain time interval of control Тint average value of the specified set mк is calculated and on a difference of average values of amplitudes in



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two next time intervals Тint the pressure of a mismatch proportional to a difference of first order∆ (1)Кm and influencing watching system, operating moving probe concerning

a seam is formed. The moving direction is regulated by a difference of second order∆ (2)Кm .

THE BLOCK DIAGRAMED OF INSTALLATION FOR THE CONTROL OF WELDED SEAMS OF PIPES

In the acoustic block of 1 acoustic system of installation НК361 (figs.3) pair probe 0 - 1 sounds a root zone of a seam on longitudinal defects, pair probe 2 - 3 sounds the top zone of

a seam on longitudinal defects. Steams probe 4 - 5, 6 - 7 and 0 - 5 acoustic blocks 2, are included under the scheme "tandem" and adjusted on revealing of longitudinal and volume defects of a welded seam. Pair 4 - 5 - in a zone from the middle to a root part of a welded seam. Pair 6 - 7 - on revealing of defects located in a zone from the middle to the top part of a welded seam.

In the acoustic block of tandem-steam 0 - 5 it is adjusted on revealing of longitudinal and volume defects in the central zone of a welded seam. probe 1, 2, 3, 4 work in immersion a variant on Х - the scheme and supervise a seam on presence of cross-section defects Д1, Д2 - gauges of laser tracking a welded seam (stabilization L - distances between a seam and probe without changes of a corner of input UST α. Fragments of a general view and the acoustic

block of installation НК361 in dynamics are presented on

figs. 4., and its structural scheme - on figs. 5.

Figs.3. Acoustic system of installation НК361



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Figs.4. Fragments of a general view and the

acoustic block of installation НК361 in dynamics

Rigid requirements on change-over time at transition to the control of pipes of other

standard size, and also requirements on reliability of system of the control automated UST have defined architecture of a control system of installations. The control system is realized on the basis of controller "Siemens" and a hand control - from the programmed panel.

On elevating rotary rollers of the transport cart the pipe is guided a welded seam in zenith, and in process of an entrance of the forward end in a zone of the control of pair probe 0 - 1 and 2 - 3 acoustic block BA1, in pairs fall on a pipe, giving of a contact liquid joins. Prior to the beginning of movement of pipe BA1 by means of system with laser gauge D1 is guided symmetrically concerning an axis of a welded seam, value of parameter Lo is entered and the algorithm of tracking a seam taking into account changes of a corner of input USF α joins.

These operating modes are regulated by a design, to equipment rooms and the software of installations

Base assembly unit of the installation providing giving of acoustic blocks on a position of the control, the bearing module of the vertical moving which rigidity of a design provides stability and repeatability of results UST. On the bearing module modules of horizontal moving are mounted. Tracking a seam in the course of the control is carried out by



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Figs.5. Structure of installation НК361 for AUST welded seams of pipes Ø of 508-1420 mm 1 - technological unit AUST; 2 - a case power; 3 - a management case;

4 - multichannel flaw detector Introscop-02; 5 - a control panel with the telemonitor; 6 - testing pipes; 7 - the transport cart.

means of system of laser tracking the platen of strengthening of a welded seam on the basis of the industrial computer.

On modules of horizontal moving acoustic blocks about US are mounted by the heads consisting from corresponding probe and the device of its fastening and orientation. Head everyone US has the pneumatic drive of lifting and the lowering, providing reliable clip to a pipe surface. Besides, on modules of horizontal moving manual drives for distance adjustment between US heads are established at adjustment. Installation is completed by the way gauge, paint markers defects, the device of preliminary wetting. For everyone paint marker the individual external capacity with a paint, being under pressure is used.

MULTICHANNEL US FLAW DETECTOR INTROSCOP-02

Detection of defects, control data processing, registration of results of calibration in the presented installations are provided with multichannel US flaw detector Introscop-02

1200

26

00

3700

2 3900

4500

4

5

900

2000

3

1850 1500

1030

0,00

6

7

1



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(figs.6) with operating computer complex on the basis of the industrial computer with the developed structure of an exchange with installation systems. All equipment is mounted in firm Shcrof case. In multichannel flaw detector the choice and input of zones of the control of metal of a welded seam and zones of quality assurance of acoustic contact (AC) is carried out программно by installed time strobes-impulses. Various variants А-scan are presented on figs.7, 8. At the control of welded seams of pipes with the big thickness of a wall for sensitivity alignment to the equal defects located on different removal from probes, and for an exception of rerejection of pipes in дефектоскопе the system of time adjustment of sensitivity - TAS is used. In each channel the shape of zones TAS setting on two curves TAS on the channel is used. Curves TAS can be formed two types - inclined and the difficult form (figs.8). Inclined curve TAS is formed on two points and such curve TAS a regulator "Inclination" copes. For strengthening change the regulator "Strengthening" which is carrying out change

of the general strengthening of a reception path is used. At use of a regulator "Inclination" straight line position changes the inclination to a horizontal axis that changes sensitivity of a path, increasing it in due course. Such TAS it is convenient to use at work with direct or inclined probes in narrow zones of the

control. Difficult curve TAS is formed by broken line-linear approximation on the points which quantity can be set in advance. The Maximum quantity of points TAS - 20. Management of the form of curve TAS is carried out by means of the manipulator "mouse". It is remarkable that the result of influence is displayed at once on the display screen. Sensitivity change occurs between two points, without mentioning other zones that allows making exact adjustment on samples. Transition from one curve TAS to

Figs.6. Multichannel flaw detector Introscop-02

Figs.7. A kind of the screen multichannel flaw detector Introscop-02 in mode А-scan



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another is carried out by switching of type TAS in an adjustment mode. If it is necessary to generate in the given channel two curves TAS it is necessary for curves to assign number 0 or 1. Further this data can be used at construction of other schemes of the control. The included mode of an electronic magnifier allows to choose a part of development and to stretch it on all screens for increase in resolution of the screen.

The computer

complex flaw detector allows making processing of the received information on defect by various rejection criteria - to amplitude, conditional extent, quantity of defects on the set site of a welded seam. Mode В-scan (figs.9) allows estimating work of all multichannel system visually: the channel of detection of defect, its parameters, relative amplitude, sites of possible loss of acoustic contact.

On figs. 10 photos микрошлифов fragments of a welded seam of a pipe in which by

means of installation НК361 defects are found out are resulted: a dispersing crack in metal of a welded seam (the first figure) and small not boiled thoroughly in an average part of a welded seam of a pipe (the second figure).

Figs.8. A mode of adjustment TAS of the difficult form

Figs.9. Mode В-scan in the course of the control



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At work of installation are provided:

► Drawing of marks of different color on a surface of the pipe, defining type and a site of defects, and also sites with infringement AC;

► Delivery of the report of the control on each pipe, including pipe number, amplitude echo-signals the found out defects of their co-ordinate, extent, numbers of the channel with defect;

► Installation calibration on the standard sample of the enterprise (SSE) - simulators of defects as in static, and a dynamic mode at the speed of moving SSE close by speed of moving of pipes in the course of the control. Results of calibration are recorded;

► Registration В-scan on each channel with possibility of viewing, the information seal on the paper carrier on all or a part of channels;

► An information transfer possibility about results of the control in system of ACSTP of shop by means of network Ethernet.

CONCLUSIONS

► New ways of tracking a welded seam in the course of its testing, the works introduced in algorithm multichannel flaw detector Introscop-02, in aggregate with the modern hi-tech equipment used at creation of installations НК361, allow to provide high reliability automated UST a welded seam of pipes of the big diameter according to requirements of international standards API 5L and DIN EN 10246-15. Revealed in the course of the automated control of a welded seam defects, after recheck by other methods are subject to repair, or lead to fall of a class of a ready pipe.

► Introduction of installations НК361 in a line трубосварочного the unit is calculated on maintenance 100 percent UST of the control at release longitudinal welded pipes in diameter 508 - 1420 mm and a wall 7 - 48 mm intended for pipeline highways.

REFERENCES: [1] Крауткремер Й., Крауткремер Г. Ультразвуковой контроль материалов: Справочник.

Перевод с нем. под. ред. проф. В.Н. Волченко.- М.: Металлургия, 1991. [In Russian].

[2] Panhans P ., patent FRG № 1473539. The device for tracking the platen of strengthening of a welded seam at not destroying control. From 14.05.1970, Mannesmann A.G.

[3] Тантлевский В.М., Квирикашвили Р.Д., Мурачев Э.С. et al. А.с. СССР № 1027599. Устройство для автоматического слежения за сварным швом. Publ. БИ, 1983, №25. [In Russian].

[4] Tcacenco А.А., Naida V., Gavrev V. et al. BREVET de inventie MD 2889 C2 2006.10.31. Peocedeu de ghidare automata a cordoanelor de sudură cu supraînălŃarea sudurii. BOPI, 2005, № 10.

Figs.10. Fragments of a welded seam with the defects which have been found out by installation НК-361: "a dispersing crack" and "not boiled thoroughly"

Documents

17 pag. 146-154. The Intelligent system of Automatic ... · 20, Mesterul Manole str., Chisinau, R. Moldova, MD-2044; [email protected] ABSTRACT Questions of automatic tracking a