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Newcastle upon Tyne, United Kingdom

Batte A.D.,Macaw Engineering | Fessler R.R.,BIZTEK Consulting Inc. | Marr J.E.,TransCanada | Rapp S.C.,Spectra Energy Transmission
PPIM 2012 - 24th Pipeline Pigging and Integrity Management Conference

A discussion on the Joint Industry Project Phase II program covers integrity management practices and experience gained in the last 5 yr concerning the application of hydrostatic testing, excavations, and in-line inspection (ILI) for integrity management of SCC in gas transmission pipelines; protocol for obtaining data from post-ILI excavations; the equivalence of ILI and hydrostatic testing; and continuous improvement for integrity management. This is an abstract of a paper presented at the Pipeline Pigging & Integrity Management Conference (Houston, TX 2/8-9/2012). Source

Andrews R.M.,Macaw Engineering | Kamping H.,Gasunie Engineering and Technology | De Haan H.,Gasunie Engineering and Technology | Huising O.J.,Gasunie Engineering and Technology | Millwood N.A.,5G Orbital
Journal of Pipeline Engineering

Industry standards for pipeline welding generally had their origins in cellulosic welding of onshore pipelines,and this is still the dominant process in some regions.Over the years standards have been adapted to include new material grades, new processes, and more-demanding applications. Even though mechanized gas-metal-arc welding (GMAW) is now the dominant process for offshore pipelines, and is widely used in some areas of the world for large-diameter long-distance cross-country pipelines, the industry standards still do not fully reflect the subtleties of this process.This results in owners and operators having to issue amending company specifications. Moreover, there have been continual technical developments in equipment and control technology which makes mechanized GMAW ever more sophisticated. The European Pipeline Research Group identified a need to develop guidelines focused on mechanized GMAW. This paper summarizes a review document produced to form the basis of such guidelines.The document has reviewed the main industry standards and also had input from company specifications. It covers typical equipment and consumables, procedure and welder qualification, typical equipment including ancillaries, production welding, inspection and testing, acceptance criteria, and repair options.It is hoped that this work will identify best practice across the industry. Based on the initial work it is intended to develop a guidance document and input into national and international standards and others working on pipeline welding requirements. Source

Andrews R.M.,Macaw Engineering | Denys R.M.,Ghent University | Knauf G.,Salzgitter Mannesmann Forschung GmbH | Zarea M.,GDF SUEZ
Journal of Pipeline Engineering

THE 1996 EDITION of the EPRG guidelines on the assessment of defects in transmission pipeline girth welds has been reviewed to extend their range of application.The revised 2014 guidelines replace and retain the three-tier structure of the old guidelines.The 2014 guidelines can be used for pipe grades up to X-80 and defect heights greater than 3 mm. A novel defect interaction criterion is given for co-planar defects in girth welds which comply with the EPRG material and performance requirements.Additionally, guidance on the pipe material and weld-metal testing requirements is given.The new guidelines provide conservative allowable defect sizes as they are fully validated by curved-wide-plate (CWP) test data. The guidelines are simple, transparent, and can be applied by users without requiring extensive experience in fracture mechanics. Source

Jackson N.,UK National Grid Corporation | Baldwin P.,Noble Denton | Andrews B.,Macaw Engineering
Institution of Chemical Engineers Symposium Series

There has been significant investment in the UK in wind power over recent years with wind power currently making up to 2.2 percent of the UK's energy supply. The UK has a target of generating 15 percent of all electricity from renewable sources by 2020 (source: Renewable UK). A significant proportion of this wind power is being provided by onshore wind turbines. These wind turbines range from small domestic wind turbines up to large utility scale wind farms. Although relatively rare, a number of wind turbine failures have occurred over the past 30 years. The extent of these failures can vary from gearbox fires through to blade failures and catastrophic failures of the wind turbine mast. These larger scale wind turbine failures could have a significant impact on buried pipelines in the vicinity of the wind turbine. These buried pipelines include high pressure gas, gasoline and oil pipelines. The failure of these pipelines would lead to the release of flammable material with potential hazards to individuals and/or property in the vicinity of the pipeline. These failures can also lead to significant energy supply failures as a result of the consequential pipeline damage. This paper summarises the work that has been undertaken by the UK Onshore Pipeline Operators' Association (UKOPA) to specify an appropriate separation distance between wind turbines and buried energy infrastructure. This separation distance has been developed using a risk-based approach to ensure that the risk of pipeline failure is acceptably low. The study was based on data collected for wind turbines in the UK and used a methodology that has been developed in the Netherlands. The study has assessed all of the wind turbine failure modes that could be a potential threat to the integrity of a pipeline including: blade failure; fall of the nacelle or rotor and toppling of the mast. © 2012 IChernE. Source

Andrews R.M.,Macaw Engineering | Millwood N.,5G Orbital | Tiku S.,BMT Fleet Technology | Pussegoda N.,BMT Fleet Technology | And 2 more authors.
Proceedings of the Biennial International Pipeline Conference, IPC

As part of a safety case for a subsea 13Cr pipeline, the operator wished to demonstrate that if a circumferential through wall crack developed, the crack would remain stable as a leak rather than growing to a full bore rupture. An initial fracture mechanics analysis had suggested that the margins on crack length were too small to make such a "leak before break" argument. This paper reports an integrated programme of small scale testing, numerical modelling and full scale testing which showed that a leak before break case could be made. 13Cr martensitic steel generally shows excellent toughness at the service temperature, as does the super duplex weld metal that was used for the girth welds. However, as the pipeline had been installed by reeling, there was some concern that the toughness may have been reduced. Hence a programme of fracture toughness testing was designed to generate tearing resistance curves for both as-received and pre-strained parent material and weld metal. Deep and shallow through thickness notched specimen geometries were tested to explore the effect of constraint on the toughness. Finite element analysis was used to predict the stress intensity for a range of crack lengths, including the effects of misalignment. Non-linear analyses were used to estimate the limit load for the cracked pipe. The test results were used as input to tearing analyses to Level 3 of BS 7910. These showed that the tolerable length of a through wall crack exceeded the length of anticipated defects by a factor of at least two. To confirm the fracture mechanics predictions, two full scale tests were carried out. These used pressure cycling to grow a through wall crack by fatigue. These cracks were stable under an internal pressure equal to the pipeline design pressure. The cracked specimens were then axially loaded to failure. Extensive tearing occurred before final failure at loads above those predicted by the fracture analysis, confirming the conservatism of the predictions. Copyright © 2012 by ASME. Source

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