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Research Update April 2017
This month, a large number of industry advisors and researchers met to review progress and set the direction of individual research projects carried in research program 3 ‘Advanced pipeline design and construction’ and research program 2 ‘Life extension of pipelines’.
On 19 April, the RP6.3-07 research project team discussed the experimental plan associated with a project that aims to develop a model of pipe resistance to damage (penetration) by various types of drilling equipment.T his model will then be used for estimating whether or not a given drill rig will be able to penetrate a pipe. This information is important for both the design of pipelines to resist drilling machines threats and in assessment of existing pipelines for resistance to drilling damage.
Drilling equipment presents a significant risk to pipelines, which is not well understood. There is limited existing basis for estimating the capability of various drilling machines (in particular HDDs) causing damage to pipelines.
As part of this research project a detailed literature and equipment review has already been completed. Researchers at the University of Wollongong have performed FEM simulations of pipe resistance to drilling operations and identified all parameters that influence the mechanism by which the drill can cause damage to the pipe (e.g. bit type, impact position, drilling speed, soil resistance). This information informs the design of a test rig using a small HDD machine as design basis. This test rig will then be used to develop a dataset that can be used to further develop the model and meet the objectives of this research project.
Industry advisors involved in the fracture research programs met to discuss the next stage of projects RP3-13 ‘EPCRC Fracture Velocity Model Validation and Implementation’ and RP6.3-07 ‘Fluid Structure Interaction Model Development’. Fracture control is one of the key research areas of the Energy Pipelines CRC, which has led to some ground breaking research outcomes over the past years. In the completed project RP3-02J Associate Prof Cheng Lu and his team at the University of Wollongong developed a fracture velocity model based on the plastic instability theory. The effect of the Y/T ratio has been included in the model for the first time to consider the effect of material ductility on the material’s resistance to facture propagation.
At the April meeting, Cheng Lu presented the results of a large number tensile tests that have been carried out to validate the model. Comparison with the experimental data indicates that the formula for the correlation of the yield-to-tensile ratio and the ratio of the uniform elongation to the total elongation, developed by the Energy Pipelines CRC give reasonably good predictions. The next stage of the projects looks further validation of the model by a number of datasets from large scale fracture propagation tests.
Guillaume Michal demonstrated a Fluid-Structure Interaction (FSI) model that was developed based on a soft coupling approach that integrates the FEA software CODE_ASTER and the CFD software ANSYS Fluent into a computing package called EPiCC. This coupled model provides a mechanism through the transfer of information between the FEA and CFD software packages, namely pressure distribution and pipe wall deformation.
EPiCC was tested using four processors for FEA and four processors for CFD by imposing a constant fracture velocity and a laminar flow using air as an ideal gas. The pipe deformation and pressure distribution were in-line with experimental knowledge and the speed of calculations was beyond expectations. As a first next step, the FSI model will be used to study influencing factors to gain a better insight on the limits of the NG 18 arrest pressure equation.
On Thursday 27 April, a large group of industry advisors met at Deakin University’s Waurn Ponds Campus to discuss a number of projects undertaken by Professor Mike Tan and his team. Mike Tan presented the outcomes of research a large research program into the effects of anodic transients, as a result of stray currents, on buried pipeline cathodic protection (CP) systems (Project RP2-08B). The results suggest that anodic transients do not necessarily cause pipeline corrosion, as long as their amplitude and duration are below critical values.
The industry advisers acknowledged the large amount of test work done in this research and the insights brought to light. Furthermore the team discussed how this research could best inform future updates of AS2832.1 Cathodic protection of metals: Pipes and cables.
Max Latino presented results from testing various commercial mainline and field joint coatings in order to quantify their role in cathodic shielding and corrosion under disbonded coatings. The results indicate to date that the majority of the tested coatings, with thicknesses typically used in the field, will shield CP in the intact condition. Results also suggest that this shielding property could be significantly affected by the thickness and ageing of coatings. A report covering the detailed results is currently under review by industry advisors and will be released in the next few weeks (Project RP2-12).
Ying Huo provided an update on project RP2-16, which aims to assess the capabilities and limitations of existing testing methods and criterion for evaluating coating defects in HDD pipelines. Results from repeated laboratory sand box testing of existing assessment methods for HDD pipeline coating defects, i.e. ‘on potential swing’ and ‘off potential’ tests were presented and compared with a new test method based EIS measurements using multi-count/reference electrodes for improving the accuracy of coating defect detection.
Bob Varela and Mike Tan provided the results of a number of field trials of a new corrosion monitoring technology. The information collected over a six-month period by eight novel electrochemical probes installed at four locations around Victoria were discussed and compared with results obtained in controlled conditions. The results of these initial trials demonstrate the capability of the probes to be used in field conditions and illustrate some of their unique advantages over current corrosion management methods. Detailed results can be found in an interim report that is currently under review by industry.