Active thermography for the investigation of corrosion in steel surfaces

The present work aims at developing an experimental methodology for the analysis of corrosion phenomena of steel surfaces by means of Active Thermography (AT), in reflexion configuration (RC). The peculiarity of this AT approach consists in exciting by means of a laser source the sound surface of the specimens and acquiring the thermal signal on the same surface, instead of the corroded one: the thermal signal is then composed by the reflection of the thermal wave reflected by the corroded surface. This procedure aims at investigating internal corroded surfaces like in vessels, piping, carters etc. Thermal tests were performed in Step Heating and Lock-In conditions, by varying excitation parameters (power, time, number of pulse, ….) to improve the experimental set up. Surface thermal profiles were acquired by an IR thermocamera and means of salt spray testing; at set time intervals the specimens were investigated by means of AT. Each duration corresponded to a surface damage entity and to a variation in the thermal response. Thermal responses of corroded specimens were related to the corresponding corrosion level, referring to a reference specimen without corrosion. The entity of corrosion was also verified by a metallographic optical microscope to measure the thickness variation of the specimens

Seismic characterization of a rapidly-rising jökulhlaup cycle at the A.P. Olsen Ice Cap, NE-Greenland

Rapidly-rising jökulhlaups, or glacial outburst floods, are a phenomenon with a high potential for damage. The initiation and propagation processes of a rapidly-rising jökulhlaup are still not fully understood. Seismic monitoring can contribute to an improved process understanding, but comprehensive long-term seismic monitoring campaigns capturing the dynamics of a rapidly-rising jökulhlaup have not been reported so far. To fill this gap, we installed a seismic network at the marginal, ice-dammed lake of the A.P. Olsen Ice Cap (APO) in NE-Greenland. Episodic outbursts from the lake cause flood waves in the Zackenberg river, characterized by a rapid discharge increase within a few hours. Our 6 months long seismic dataset comprises the whole fill-and-drain cycle of the ice-dammed lake in 2012 and includes one of the most destructive floods recorded so far for the Zackenberg river. Seismic event detection and localization reveals abundant surface crevassing and correlates with changes of the river discharge. Seismic interferometry suggests the existence of a thin basal sedimentary layer. We show that the ballistic part of the first surface waves can potentially be used to infer medium changes in both the ice body and the basal layer. Interpretation of time-lapse interferograms is challenged by a varying ambient noise source distribution.ISSN:0022-1430ISSN:1727-565

30th International Conference on Condition Monitoring and Diagnostic Engineering Management (COMADEM 2017)

Proceedings of COMADEM 201

Testing of Materials and Elements in Civil Engineering

This book was proposed and organized as a means to present recent developments in the field of testing of materials and elements in civil engineering. For this reason, the articles highlighted in this editorial relate to different aspects of testing of different materials and elements in civil engineering, from building materials to building structures. The current trend in the development of testing of materials and elements in civil engineering is mainly concerned with the detection of flaws and defects in concrete elements and structures, and acoustic methods predominate in this field. As in medicine, the trend is towards designing test equipment that allows one to obtain a picture of the inside of the tested element and materials. Interesting results with significance for building practices were obtained

Development of shore platforms on Kaikoura Peninsula, South Island, New Zealand

Shore platforms on the Kaikoura Peninsula have been examined to determine the roles of marine and sub aerial weathering processes in platform evolution. Erosion was measured to assess rates of development and processes of erosion. Lowering rates on platforms are presented from two years of monitoring using a traversing micro-erosion meter. Cliff retreats were calculated using aerial photographic interpretation. Marine processes were investigated by using deep water wave data, by measuring waves on shore platforms and by analysing measured tidal data. Weathering processes were investigated using tidal data, climate data, the Schmidt Hammer test, and a laboratory experiment on wetting and drying. Lowering rates over two years ranged from 0.07 to19.80mm, and annual rates ranged from 0.154 to 9.194mm/yr. Rates of erosion varied with lithology and the type of platform. Erosion on Type A mudstone platforms was 1.98mm/yr; on Type B mudstone platforms erosion was 0.733mm/yr; and on limestone platforms it was 0.88mm/yr. The grand mean lowering rate for all shore platforms was 1.13mm/yr. These rates fall in the middle of the range of published rates from previous studies at Kaikoura and at locations around the world. For the first time, erosion data from a traversing micro-erosion meter were presented as volumes of material eroded. The total volume of rock eroded from study sites having, each with an area of 45.4cm2 , ranged from 1.20 to 92.50cm3. A significant finding was that rock surfaces swell up as indicated by a rise in surface level rather than lowering from erosion. The maximum measured swelling was 8.90mm. At some measurement sites as much as 90 per cent of measurements showed swelling over a period of 98 days. Values for erosion and swelling were higher during summer months. Both erosion and swelling were shown to be statistically related to season, suggesting that weathering is the group of processes causing both erosion and swelling. Summer provides better conditions for wetting and drying, which is thought to be the most important weathering process on shore platforms. Horizontal retreat rates were calculated over 52 years for cliffs, beaches and lagoon deposits backing shore platforms at Kaikoura, these ranged from 0.05 to 0.91m/yr. Investigation of marine processes showed that the deep water wave environment off the Kaikoura Peninsula is very energetic, but the amount of wave energy delivered to platforms is very low. A comparison of deep water wave energy flux with wave energy flux at the landward cliff of platforms, showed that there was a reduction by as much as five orders of magnitude. An analysis of the role of breaking waves revealed that these were ineffective as an erosional agent because the depth of water offshore causes breaking well before waves arrive on platform surfaces. Shear stresses and dynamic forces under waves were calculated from waves measured on shore platforms. This showed that these forces never exceeded the compressive strength the platform rocks at Kaikoura. It was concluded that wave forces are not directly capable of causing erosion. Evidence of weathering on shore platforms came from a number of distinctive surface morphologies on platforms: honeycombs, salt crystal growths, water layer weathering; and slaking. Schmidt Hammer test data showed: firstly, that weathering had occurred; and secondly, that rock strength was reduced through weathering by as much as 50 per cent. Weathering processes on shore platforms rely on repeated wetting and drying, and for this reason the number of wetting and drying cycles was estimated. The number of cycles ranged from 104 to 379 per year, the variation was due to tidal influences and the growth of algae during winter months. At elevations low in the tide range fewer cycles occurred; the greatest number occurring between the peaks of spring and neap tides, where rainfall adds to the number. Most cycles were estimated to occur between 0.6 and 0.9m above mean sea level on the more landward margins of platforms. It was at these elevations and locations that the highest rates of erosion were measured. Laboratory experiments on wetting and drying showed that only one cycle was needed to cause erosion. Waves were shown not to cause erosion, while sub aerial weathering does. Statistical analysis showed significant relationships between erosion, and wetting and drying and elevation. Based on these results it was concluded that the development of shore platforms at Kaikoura relies on weathering resulting from repeated wetting and drying. This is contrary to recent work which proposed that shore platforms result from marine erosion. Published mathematical models of shore platform development were found to be invalid at Kaikoura, because they were designed on the assumption that platforms are indeed wave cut features. This assumption is incorrect for shore platform development at Kaikoura. An empirical model is presented to explain platform evolution and the differences in platform morphology. A separation between platform types is presented based on the ability of weathering to cause erosion and on compressive strength. This is contrary to a published demarcation between types based on the erosive force of waves and on compressive strength. The type of equilibrium that platforms tend towards is considered. It is proposed that there are two ways to consider equilibrium. First, platforms may be lowered to an as-yet-unidentified elevation; this was viewed as being a static form of equilibrium. Secondly, platforms may continuously widen because weathering is an ongoing process. It was proposed that there is no equilibrium width for shore platforms

Investigating the build-up of precedence effect using reflection masking

The auditory processing level involved in the build‐up of precedence [Freyman et al., J. Acoust. Soc. Am. 90, 874–884 (1991)] has been investigated here by employing reflection masked threshold (RMT) techniques. Given that RMT techniques are generally assumed to address lower levels of the auditory signal processing, such an approach represents a bottom‐up approach to the buildup of precedence. Three conditioner configurations measuring a possible buildup of reflection suppression were compared to the baseline RMT for four reflection delays ranging from 2.5–15 ms. No buildup of reflection suppression was observed for any of the conditioner configurations. Buildup of template (decrease in RMT for two of the conditioners), on the other hand, was found to be delay dependent. For five of six listeners, with reflection delay=2.5 and 15 ms, RMT decreased relative to the baseline. For 5‐ and 10‐ms delay, no change in threshold was observed. It is concluded that the low‐level auditory processing involved in RMT is not sufficient to realize a buildup of reflection suppression. This confirms suggestions that higher level processing is involved in PE buildup. The observed enhancement of reflection detection (RMT) may contribute to active suppression at higher processing levels

Recent Advances in Pipeline Monitoring and Oil Leakage Detection Technologies: Principles and Approaches

Pipelines are widely used for the transportation of hydrocarbon fluids over millions of miles all over the world. The structures of the pipelines are designed to withstand several environmental loading conditions to ensure safe and reliable distribution from point of production to the shore or distribution depot. However, leaks in pipeline networks are one of the major causes of innumerable losses in pipeline operators and nature. Incidents of pipeline failure can result in serious ecological disasters, human casualties and financial loss. In order to avoid such menace and maintain safe and reliable pipeline infrastructure, substantial research efforts have been devoted to implementing pipeline leak detection and localisation using different approaches. This paper discusses pipeline leakage detection technologies and summarises the state-of-the-art achievements. Different leakage detection and localisation in pipeline systems are reviewed and their strengths and weaknesses are highlighted. Comparative performance analysis is performed to provide a guide in determining which leak detection method is appropriate for particular operating settings. In addition, research gaps and open issues for development of reliable pipeline leakage detection systems are discussed. Document type: Articl

Recent advances in pipeline monitoring and oil leakage detection technologies: principles and approaches.

Pipelines are widely used for the transportation of hydrocarbon fluids over millions of miles all over the world. The structures of the pipelines are designed to withstand several environmental loading conditions to ensure safe and reliable distribution from point of production to the shore or distribution depot. However, leaks in pipeline networks are one of the major causes of innumerable losses in pipeline operators and nature. Incidents of pipeline failure can result in serious ecological disasters, human casualties and financial loss. In order to avoid such menace and maintain safe and reliable pipeline infrastructure, substantial research efforts have been devoted to implementing pipeline leak detection and localisation using different approaches. This paper discusses pipeline leakage detection technologies and summarises the state-of-the-art achievements. Different leakage detection and localisation in pipeline systems are reviewed and their strengths and weaknesses are highlighted. Comparative performance analysis is performed to provide a guide in determining which leak detection method is appropriate for particular operating settings. In addition, research gaps and open issues for development of reliable pipeline leakage detection systems are discussed

Proceedings of the 10th International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurized Components

This conference, the tenth in a series on NDE in relation to structural integrity for nuclear and pressurized components, was held from 1st October to 3 October 2013, in Cannes, France. The scientific programme was co-produced by the European Commission’s Joint Research Centre, Institute for Energy and Transport (EC-JRC/IET). The Conference has been coordinated by the Confédération Française pour les Essais Non Destructifs (COFREND). The first conference, under the sole responsibility of EC-JRC was held in Amsterdam, 20-22 October 1998. The second conference was locally organized by the EPRI NDE Center in New Orleans, 24-26 May 2000, the third one by Tecnatom in Seville, 14-16 November 2001, the fourth one by the British Institute of Non-Destructive Testing in London, 6-8 December 2004, the fifth by EPRI in San Diego, 10-12 May 2006, the sixth by Marovisz in Budapest, 8-10 October 2007, the seventh by the University of Tokyo and JAPEIC in Yokohama, the eight by DGZfP, 29 September to 1st October 2010, the ninth by Epri NDE Center, 22-24 May 2012 in Seattle. The theme of this conference series is to provide the link between the information originated by NDE and the use made of this information in assessing structural integrity. In this context, there is often a need to determine NDE performance against structural integrity requirements through a process of qualification or performance demonstration. There is also a need to develop NDE to address shortcomings revealed by such performance demonstration or otherwise. Finally, the links between NDE and structural integrity require strengthening in many areas so that NDE is focussed on the components at greatest risk and provides the precise information required for assessment of integrity. These were the issues addressed by the papers selected for the conference.JRC.F.5-Nuclear Reactor Safety Assessmen