The NDE-Inspection of austenitic austenitic and dissimilar welds gives still the highest demands on the industry. The well known circumstances are the varied grain size, the dendritic structure, the changing sound velocity and the geometrical conditions like weld shape and component form. Very often only single side access is possible. Each institute or company in the NDE buisness is working on a partial development of the inspection system or inspection technique.

But until today no general solution was found for building a NDE-UT-System which is easy to handle, efficient and gives us results which are close to 100% of the reality. In most cases the opimization of an inspection technique starts with the simulation of the infield conditions. Then the available parts of the inspection system are optimized under the aspects of cost minimization and a maximum of effectivness. The result can always be only a compromise for this special application - unknown condition changes infield can influence the results extremly in a negative way.

For developing a cost saving system which is less dependent on different conditions in field it would be an advantage to be able to fullfill the following criteria: At each probe position an optimized angle of incidence should be possible. A single probe arrangement should carry probes with varrious wave modes for all necessary scan directions. The transducers should be optimized in pulse, signal shape and filter, in consideration of UT-equipment and cables. All relevant data should be recorded without taking care about the range of data set size. The evaluation tools should be easy to handle and shoud be defined by UT-inspectors with practice experience. For flaw sizing and characterization there should be automatically software tools available. The reports should be generated automatically under aspects of quality control. The system should show a high integrity level There should be a high acceptance by user and authority of the complet system

This criterias demonstrate, that only a total integrated UT-System can bring us a step forward to more clear results. Figure 1shows the necessary parts of a UT-System.

Fig 1: UT-System Sketch

One UT-System which is based on this criterias is the SAPHIR Phased-Array-System manufactored by SIEMENS KWU ( see )
The probes are based on composit-cristals which gives shorter pulses and a better signal to noise ratio. The probes can be built in smaler housings at a lower cost level. The probes can be used as single or dual transducers. They generate shear waves for the detection in the base material and longitudinal waves for the detection through the weld or the buttering. Creeping waves for the detection at the nearsurface area and mode conversion with CE2 and CE1 for flaw detection and classification can be generated. For sizing ,characterization and flaw shape modelling, several different angles can be used at one probe position. Even a 0° function for coupling checks, contour and wallthickness measurments for discriminaing of geometrical indications can be realized ( Fig 2).

Fig 2: Example for Dual Phased Array Probe

Dual Transducer with: 2x8 Element 1.8 MHz Angle of incidence 30° to 70° shear 36° to 79° long wave 0° for coupling check Inspection Functions creeping wave longitudinal wave shear wave mode conversion

Fig.3: Probe Arrangment for Nozzles

A probe arrangement existing of three probes ( Fig 3 ) can reduce a UT-Inspection at dissimilar welds with single side access to a one scan examination.

All exit points for one scanning direction are always well defined. Up to 5 of thuch 16 Element probes can be connected to one SAPHIR System. They can be activated simultaniously durring one scan. A combination of Phased Array Probes and Standard Probes in one arrangement for special sizing efforts is also possible. The connectors and cabels are optimized for less noise and havy conditions like underwater inspections up to 40 m.

In the UT-System the ALOK-filter algorithme is implanted. This algorithme can be used for filtering indications by their echo shape but can be also switch of for collecting full A-Scans.
The analyze software was developed by upgradeing the well knwon a over several years stable running ALOK-"System 85" software. The software is now running on powerfull HP-Workstations which allows a multi-user working on one analyze station on two terminals. The expanded evaluation features were spezified and continously tested by inspection personnel.
For easy infield quality control a automatic self-test is implantet which reports a stable sensitivity.
The online coupling check gives a quick overview of the main indications and the noiselevel. By the C-Scan concret information of the position of all indications are transmitted. ( Fig.4 )

Fig 4: Fig. 4: Projection View	1. Step 1.1. detection each single angle, direction superimposed localisation of indication measurement of all 3 dimensions measurement of the amplitude amplitude correlation to registration level 1.2. characterization indication shape indication extrimities ckrack tips
Also the shape of the reflector can be visualized by using superimposed pictures of different angles of incidence and scanning directions. In the TD-Scans echo dynamics in each scanline can be evaluated and echo dynamics of tips can be analysed. ( Fig. 5 )
Fig 5: TD-SCAN-View	2. Step sizing and discrimination TD-SCAN echo-dynamic shape tip dynamics A-Scan signal shape moving signal tip signal

The A-Scan presentation gives the posibility to restore the A-Scans of each single shot for looking for crack tips and analyzing the signal shape for characterization of the indication. The standard reconstruction tool for flaw discrimination and thruwall sizing is a geometrical reconstruction ( Fig. 6)


Fig. 6: Reconstruction Tools

Optional software reconstruction routines based " Holography" or " SAFT"-algorithme can be implanted. Various features of automatic documentation optimize the quality control and minimize defects and the paperwork for the inspector. ( Fig.7 )

Fig.7: Documentation

One of the next steps of development realizing will be the combination with a background databank for comparing the indication with former once. An other is the combination of different NDE-techniques like EC and X-Ray under one single presentation surface with the possibility of superimpose. This development and the official qualification takes time and a lot of money, therefore only a cooperation of institutes and industries on a broad base can bring a large step forward in this technology.

Author

Friedrich Mohr,
born 1958, graduated in general theoretical and practical material sience, surface and corrosion techniques at Friedrich - Alexander - University in Erlangen in 1984. From 1983 until 1986, research engineer at SIEMENS AG KWU for eddy current techniques. Since 1986 research engineer at SIEMENS AG KWU for ultrasonic techniques. The work is focused on optimization and development of automatic UT-Systems ( ALOK, PSCAN, TOMOSCAN, LSAFT, HOLO3000, PHASCAN ). Qualification of the systems and training of adequate personnel is also part of the work. In several qualification programs like IGSCC, PISC, NESC, VIP, PDI etc. and first field expierence the capability of the developments were demonstrated world wide. Since 1994 additionally, design and manufacturing of UT- and ET- probes (including Phased Array and EMAT ) became part of the workfield.
E-mail: Friedrich.Mohr@erl11.siemens.de
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The Paper was presented on the UTonline Application Workshop in May '97