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:|
|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:
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
1.1. detection each single angle, direction superimposed
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
sizing and discrimination
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)
|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 )|| |
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.
The Paper was presented on the UTonline Application Workshop in May '97
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