TY - CONF A1 - Haith, M. I. A1 - Ewert, Uwe A1 - Hohendorf, Stefan A1 - Bellon, Carsten A1 - Deresch, Andreas A1 - Huthwaite, P. A1 - Lowe, M. J. S. A1 - Zscherpel, Uwe T1 - Modelling based radiography for NDE of subsea pipelines N2 - This work presents the use of limited experimental measurements to develop a set of calibrated Simulation parameters that can then be used for reliable simulation of subsea pipeline inspections. The modelling software aRTist is used as the simulation tool, and the calibration is through comparison with experimental images of a well characterised sample in a water tank. Image Quality parameters such as signal-to-noise ratio, contrast and basic spatial resolution are compared with the aim of matching simulated values to experimental results. Currently the model is partially calibrated, with signal-to-noise ratio successfully matched while differences are still found in contrast-to-noise ratio comparisons. This means that measurements depending on absolute intensity are not accurate enough in the simulation at this stage. However, the simulation is found to be accurate for wall thickness measurements in tangential images, which are not based on absolute intensity, with simulated and experimental cases producing similar results. T2 - 42nd Annual Review of Progress CY - Minneapolis, Minnesota, USA DA - 26.07.2015 KW - Modelling KW - Radiography KW - Pipeline inspection KW - Nondestructive evaluation PY - 2016 SN - 978-0-7354-1353-5 U6 - https://doi.org/10.1063/1.4940575 SN - 0094-243X VL - 1706 SP - 110004-1 EP - 110004-8 PB - AIP Publishing AN - OPUS4-37553 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ewert, Uwe A1 - Martin Tschaikner, Martin A1 - Hohendorf, Stefan A1 - Bellon, Carsten A1 - Haith, M. I. A1 - Huthwaite, P. A1 - Lowe, M. J. S. T1 - Corrosion monitoring with tangential radiography and limited view computed tomography N2 - Accurate and reliable detection of subsea Pipeline corrosion is required in order to verify the integrity of the pipeline. A laboratory trial was conducted with a representative pipe sample. The accurate measurement of the wall thickness and corrosion was performed with high energy X-rays and a digital detector array. A 7.5 MV betatron was used to penetrate a stepped pipe and a welded test pipe of 3 m length and 327 mm outer diameter, with different artificial corrosion areas in the 24 mm thick steel wall. The radiographs were taken with a 40 x 40 cm² digital detector array, which was not large enough to cover the complete pipe diameter after magnification. A C-arm based geometry was tested to evaluate the potential for automated inspection in field. The primary goal was the accurate measurement of wall thickness conforming to the standard. The same geometry was used to explore the ability of a C-arm based scanner in asymmetric mode for computed tomography (CT) measurement, taking projections covering only two thirds of the pipe diameter. The technique was optimized with the modelling Software aRTist. A full volume of the pipe was reconstructed and the CT data set was used for reverse engineering, providing a CAD file for further aRTist simulations to explore the technique for subsea inspections. T2 - 42nd Annual Review of Progress in Quantitative Nondestructive Evaluation CY - Minneapolis, Minnesota, USA DA - 26.07.2015 KW - Corrosion monitoring KW - Tangential radiography KW - Computed tomography PY - 2016 SN - 978-0-7354-1353-5 U6 - https://doi.org/10.1063/1.4940574 SN - 0094-243X VL - 1706 SP - 110003-1 EP - 110003-8 PB - AIP Publishing AN - OPUS4-37555 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ewert, Uwe A1 - Redmer, Benrhard A1 - Schumacher, David A1 - Thiessenhusen, Kai-Uwe A1 - Bellon, Carsten A1 - Nicholson, P. I. A1 - Clarke, A. L. A1 - Finke-Härkönen, K.-P. T1 - X-ray tomographic in-service inspection of girth welds – the european project tomoweld N2 - The new standard ‘ISO 17636-2:2013: Non-destructive testing of welds — Radiographic testing — Part 2: X- and gamma-ray techniques with digital detectors’, defines the practice for radiographic inspection of welded pipes for manufacturing and in-service inspection. It is applied in Europe for inspections of pipe welds in nuclear power plants as well as in chemical plants and allows a faster inspection with digital detector arrays (DDA) than with film. Nevertheless, it does not allow the evaluation of the depth and shape of volumetric and planar indications. In 2001 a planar tomography scanner, TomoCAR, was introduced for mechanized radiographic testing (RT) inspection and non-destructive measurement of cross sections. The project TomoWELD is based on a new concept of the scan geometry, an enhanced GPU based reconstruction, and the application of a new generation of photon counting DDAs based on CdTe crystal CMOS hybrids. The new detector permits the selection of energy thresholds to obtain an optimum energy range and reduction of the influence of scattered radiation. The concept and first measurements are presented. Flaw depth and shape of volumetric and planar irregularities can be determined. T2 - QNDE 2014 CY - Boise, Idaho, USA DA - 20.07.2014 KW - X-ray imaging KW - Tomography KW - Engineering inspection KW - Radiography KW - Welded joints KW - Chemical plants PY - 2015 SN - 978-0-7354-1292-7 U6 - https://doi.org/10.1063/1.4914650 SN - 0094-243X N1 - Geburtsname von Schumacher, David: Walter, D. - Birth name of Schumacher, David: Walter, D. VL - 1650 SP - 525 EP - 533 PB - American Institute of Physics AN - OPUS4-36581 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wieder, Frank A1 - Ewert, Uwe A1 - Vogel, Justus A1 - Jaenisch, Gerd-Rüdiger A1 - Bellon, Carsten T1 - A Novel Multi Slit X-Ray Backscatter Camera Based on Synthetic Aperture Focusing N2 - A special slit collimator was developed earlier for fast acquisition of X-ray back scatter images. The design was based on a twisted slit design (ruled surfaces) in a Tungsten block to acquire backscatter images. The comparison with alternative techniques as flying spot and coded aperture pin hole technique could not prove the expected higher contrast sensitivity. In analogy to the coded aperture technique, a novel multi slit camera was designed and tested. Several twisted slits were parallelly arranged in a metal block. The CAD design of different multi-slit cameras was evaluated and optimized by the computer simulation packages aRTist and McRay. The camera projects a set of equal images, one per slit, to the digital detector array, which are overlaying each other. Afterwards, the aperture is corrected based on a deconvolution algorithm to focus the overlaying projections into a single representation of the object. Furthermore, a correction of the geometrical distortions due to the slit geometry is performed. The expected increase of the contrast-to-noise ratio is proportional to the square root of the number of parallel slits in the camera. However, additional noise has to be considered originating from the deconvolution operation. The slit design, functional principle, and the expected limits of this technique are discussed. T2 - 43rd Annual Review of Progress in QNDE CY - Atlanta, GA, USA DA - 17.07.2016 KW - Deconvolution KW - Back scatter imaging KW - Computer simulation KW - Aperture focusing PY - 2017 SN - 978-0-7354-1474-7 U6 - https://doi.org/10.1063/1.4974711 VL - 1806 SP - 1 EP - 9 PB - AIP Publishing AN - OPUS4-42429 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -