Table of Contents ECNDT '98
MAPPscan - Acoustic Positioning System for Manual Ultrasonic testing of Pipes and Componets.P-H Svahn
SAQ Kontroll AB
Corresponding Author Contact:
SAQ Kontroll AB, SE-431 53 MOLNDAL - Sweden, Tel: +46-31-866000, Fax: +46-31-866162
|TABLE OF CONTENTS|
MAPPscan is a manual ultrasonic testing system connected to an acoustic positioning system.. The system is developed as a consequence of the increased radiation doses in nuclear plants . The system has the same flexibility as manual scanning with the same accuracy and the possibilties to collect, store and evaluate the UT data as with mechanised Ultrasonic systems.
The positioning system is based on spatial acoustic triangulation and have an accuracy of better than 1.0 mm within its recommended range.
Advantages of the MAPPscan system compared to a manual system:
Fig 1: The positioning system
The UT-Acquisition system hardware consists of a 1 channel ultrasonic board, for puls/echo, one or two crystal probes. It operates within a frequency range of 0,5 - 15 Mhz and with variable sampling frequencies in steps of 20,40 or 80 MHz.
The software contains features such as TCG- compensation, information on probe rotation, compensations for object geometry and can provide a choice of A- , B- and C-scan images while scanning.
The software also hosts a maximum amplitude function which ensures that the signal with the largest amplitude is stored for each point. This function also guarantees that such a signal is not written over by a following scan producing a lower amplitude signal at the same point. It can also provide a full documentation of data set parameters.
|Fig 2: The MAPPscan SYSTEM Layout|
The Evaluation system is a Windows based open system through DLL, Dynamic Link Library, which provides great flexibility in evaluation and presentation of data. It also makes it possible to customise evaluation and images for special applications. The time gates can be set after testing and there is a 256 colour range for amplitude. The software include FFT -facilities which enables measurements on used probes for parameters such as center frequenzy and bandwidth.
Another feature is a repositioning program (Repos.exe) which is used for the purpose of correcting positioning data collected when scanning on a pipe elbow or when scanning is performed with the microphone collar mounted on the elbow itself.
This type of scanning produces positioning data which is false in both x- and y-direction caused by the fact that acqusition software operates assuming that the shape of the test object is cylindrical. The acqusition file has then to be processed by the repositioning program before processing of the UT-data together with the positioning data for evalutation can be performed.
The system has been in full use during the shutdown periods of 1996 and 97 in the nuclear industry in Sweden. Performed tests have produced excellent results under sometimes difficult conditions.
The system has been qualified under the new regulations for ISI in Swedish nuclear plants, SKIFS, during the spring of 98.
The system has proven to be a powerful tool for inspections in the Nuclear industry with the potential of reducing the radiation doses for a highly qualified group of personnel and at the same time ensure a high quality and reproducibility of testing.