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 - JOUR 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 - Radiographic modelling for NDE of subsea pipelines N2 - This work presents an investigation of the accuracy of a radiographic simulation model applied to subsea pipeline inspections. Experimental measurements of a sample in a water tank are used to develop a set of calibrated simulation parameters for the modelling software aRTist. Image quality parameters such as signal-tonoise ratio, contrast and basic spatial resolution are compared with the aim of matching simulated values to experimental results. With this method signal-to-noise ratio was successfully matched while differences were still found in contrast-to-noise ratio comparisons. This means that measurements depending on absolute intensity are not accurate enough, however wall thickness measurements in tangential images, which are not based on absolute intensity, were found to produce similar results in simulated and experimental cases. The differences in contrast and intensity are thought to be due to detector backscatter and additional scatter from out-of-setup objects within the exposure bay, due to a lack of source collimation. These would affect the experimental results but were not included in the simulated setup. This was investigated by including different proportions of peripheral water and other objects in the modelled setup and examining the effect on Image quality parameters. Results show that this additional scatter has a significant impact on the radiograph, particularly on image contrast, and is therefore the likely cause of differences between experimental and simulated images. This implies that it will be very difficult to completely match simulated to experimental results, as including all possible scattering objects in the model would be very complex. An improvement could be made by using real subsea data to estimate this additional scattering, which could then be used to calibrate the model. However there would still be significant uncertainty in the ability of the model to accurately produce realistic intensity and contrast. KW - Digital radiography KW - Modelling validation KW - Subsea pipeline inspection KW - Tangential radiography PY - 2017 U6 - https://doi.org/10.1016/j.ndteint.2016.11.006 SN - 0963-8695 SN - 1879-1174 VL - 86 SP - 113 EP - 122 AN - OPUS4-39053 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -