Digital Radiographic Inspection replacing traditional RT and 3D RT Development Iploca Novel Construction Meeting 27&28 March 2014 Geneva By Jan van der Ent Technical Authority International
Contents Introduction of Digital Radiography Advantages of digital radiography Digital Radiography inspection methodology RTD RAYSCAN system Digital detector and Image processing principle Time delayed integration Image Quality indicator Software features Practical benefits of RTD RAYSCAN Future development, 3D tomography 2
Introduction of Digital Radiography Radiographic image = x-ray image (photography) RTR = Real Time Radiography = direct x-ray image 3
Digital RTR vs. Conventional RT Advantages of digital vs. conventional RT: Shorter exposure times (due to high sensitivity) Reduced angle of radiation beam Improved radiation safety (lower kev) Direct on-line weld image display No residual products lower costs No use of chemicals No film Large dynamic range (multiple film classes covered) 4
Geometric unsharpness comparison Panoramic film Directional film RAYSCAN METHODOLOGY Detector External source Crawler IMAGE 1 IMAGE 2 IMAGE 3 Image 1 : Poor geometric un-sharpness, high radiation risk! Image 2 : Multiple exposures, high radiation risk! Image 3 : RAYSCAN system methodology Eliminates geometrical un-sharpness Eliminates multiple images Reduces the radiation risk 5
Movie Rayscan system 6
Digitial RT system development Shielded 2 12 16 20 24 Unshielded 7
The heart of the Rayscan: Digital Sensor Active area Rayscan uses a digital sensor (like a digital photocamera... but for Xrays) The Xray-photographs are 6mm wide and up to 220mm long 300 photographs (or frames) a second are being made! Software re-constructs all photographs to a complete weldimage High efficiency of sensor makes it possible to inspect large wall thicknesses with relative low radiation. 8
Digital X-ray detector principle Direct detection of x rays with: Biased semiconductor Collection array X-ray photons hit the semiconductor X-ray photons generate charges in semiconductor Field separates charges Charges are processed by collection array Dielectric layer Incident x-ray Field photons electrode Semiconductor Collection array (signal to computer) 9
RTR inspection methodology DWSI technique used in the RTR system Tube and detector rotate around the pipe and the data is processed. After full rotation the whole weld is captured and processed by the software. Tube Pipe Detector 10
Time Delayed Integration (TDI) The detector has to read at least one image when it moves by the width of a pixel. The (e.g.) seven pixel rows of the detector acquire different parts of the weld (color). Tube Pipe 1. frame 1 2 3 4 5 6 7 1 2 3 4 5 6 7 Detector 11
Time Delayed Integration (TDI) The detector moves. For the second acquisition the seven pixel rows cover a new area of the weld, i.e., additionally mid blue but not dark red anymore) The pixel rows are shifted by one row. Tube Pipe 2. frame 1 2 3 4 5 6 7 1. frame 1 2 3 4 5 6 7 Detector 12
Time Delayed Integration (TDI) After another acquisition the pixel rows are shifted by two with dark blue as an additional weld area. And so forth for all acquisitions! Tube Pipe 3. frame 1 2 3 4 5 6 7 1 2 3 4 5 6 7 2. frame 1 2 3 4 5 6 7 1. frame 1 2 3 4 5 6 7 Detector 13
Image Reconstruction The software has to resort the acquired data by taking into account the shift in rows. The 1. frame gives the image data for the first seven pixels. The 2. frame is shifted by one pixels and is added to the image data shifted by one. The 3. frame is shifted by two pixels and added accordingly. 3. frame 2. frame 1. frame image data 1 2 3 4 5 6 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7 pixel position The image builds up from the frames by integration (summing up). The number of frames depends on the pixel rows of the detector. 14
RTD RayScan system performance Minimal motion un-sharpness No film un-sharpness Image quality equal or better than film or other digital RT High performance (using constant potential X-ray ) with lower radiation, see example below; Conventional directional X ray 300 kev x-ray radiation Digital CP RT 160 kev x-ray radiation Noise reduction improved image quality 15
Image Quality Indicators (IQI) According to EN 1435, soon to be accepted ISO 17636 part 1 and 2 (DR) IQI s are used to measure sensitivity and spatial resolution Single : Sensitivity Double : Spatial resolution Single wire IQI Double wire IQI (Rayleigh criterion >20%) 16
Image Enhancement with RTD RayScan Brightness Contrast Wall Thickness 16mm, 8 CS - 175kV, 4mA 17
Digital Zoom with RTD RayScan Cluster porosity Source side IQI 13th wire visible Scattered porosity Wall Thickness 16mm, 8 CS - 175kV, 4mA 18
Defect Evaluation and Marking 19
Practical Benefits of RTD RayScan Typical benefits of RTD RAYSCAN No films or consumables, no storage cabinets required No darkroom, no processors or chemicals (chemical waste) No waiting time for film development Less personnel (scanner tech + operator) Digital enhancement tools Lower radiation Wide range of pipe sizes and wall thickness However also the Digital radiographic inspection technique, despite the mentioned benefits, is limited to the use of standard workmanship acceptance criteria as no defect height can be measured. 20
3D Development: Applus RTD TomoCAR for Accurate Defect Sizing and Characterization 21
Why 3D Radiographic Inspection? Defect orientation Defects can be missed due to orientation Position of Source relative to film Defects can be missed due to orientation Operator subjective interpretation Influence of human judgment Probability of Detection Is negative influence by above factors Standard Radiographic Doesn t offer defect height sizing Main objectives are : To improve the Probability of Detection To introduce ECA based acceptance criteria into the RT inspection
Inspection principle 3D testing of objects 100-1000 projections High measurement time
Scanning in X direction through weld X X -scan direction Defect height visible in cross section 24
Defect height System Data analysis 25
Thank you! Jan van der Ent ApplusRTD Technical Authority Pipeline Department What is more in the pipeline? 26