Corrosion modelling in Brazil

A practical approach in pipeline corrosion modelling: Part 2 – Short term integrity forecasting, by Dr Érika S M Nicoletti, Ricardo Dias de Souza, and Dr Sérgio da Cunha Barros, Petrobras Transporte SA, Rio de Janeiro, RJ, Brazil.

The pipeline industry is ever more subjected to the increased demands of profitability, operational safety and environmental friendliness. Achieving maintenance-cost reductions while keeping or improving a system’s overall reliability requires enhanced fitness-for-purpose analyses, for which a limit-state approach is most suited. Many of the current pipeline defect assessment codes have embraced this concept, although none provide clear and concise guidance on the specific subjects of forecasting corrosion growth and estimating in-line inspection (ILI) tool measurement error, which provide the foundation for such assessments.

The research outlined was carried out in order to provide a set of guidelines on modelling and analysis procedures for corrosion metal-loss growth on ageing pipelines, using as its input corrosion monitoring and inspection data. A predictable relationship between the corrosion growth rate and its standard deviation has been established, and a short-term forecasting model has been developed, both of which have been verified in two case studies. The authors show that their model can easily be implemented using commercially available mathematical spreadsheets, and the entire procedure demands little skilled work. The results are highly reproducible, with their overall quality relying mostly on the consistency of the input data.

Bamboo pipelines for China?

Bamboo pipelines in ancient China (and now?), by Jiexin Zheng, State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian, China, and Professor Andrew Palmer, Department of Civil Engineering, National University of Singapore, Singapore.

Long ago, China began to develop a system of bamboo flowlines around the city of Zigong: motivation for this extraordinary development was production of salt brine and natural gas from the thick beds of salt that underlie the Sichuan Basin. The earliest wells were hand-excavated, but in about 1000 AD the Chinese invention of cable-tool drilling enabled much greater depths to be reached, culminating in the Shenghai well, which reached 1,001 m in 1835. This technology was later copied in North America; first for water wells and later for oil wells.

While – at one level – bamboo pipelines are mainly of antiquarian interest, the authors suggest that the technology could also be applied today. Imagine a low-pressure pipeline in a water development in a landlocked and very poor country with little manufacturing capability, such as Laos. A development expert flown in from outside would automatically think of steel or polyethylene pipes, and these would have to be brought from abroad at a high cost in foreign currency and energy, transported hundreds of kilometres over bad roads, and joined together by expert welders. Bamboo, on the other hand, grows everywhere and there is no shortage of labour, and so a bamboo pipeline might be a more sophisticated solution. It needs no foreign currency, can be put together by local workers, and is not a burden on the environment, being sustainable and biodegradable.

HDD risk mitigation: the Netherlands

The trenchless technique for horizontal directional drilling: soil-related risks and risk mitigation, by Dr Henk Kruse, Geo-Engineering Unit, Deltares National Institute, Delft, Netherlands.

Horizontal directional drilling is a deservedly popular technique, and while the majority of the cables and pipelines installed in this way succeed, the process lacks sufficient control of the risks arising from subsurface conditions. Consequently, a soil-related risk analysis for predicting unwanted events during the drilling stages, or after installation, is recommended. Identification of the risks is the most important stage in such a risk analysis, and requires sufficient knowledge of the processes during the drilling stages. The author discusses the most often occurring of these soil-related risks and their mitigation, which include: high pulling forces or incomplete pull-back caused by local bore instability or frictional forces in the bore, and seepage through the bore to the surface.

Pipeline integrity in the US

Legal issues in pipeline integrity programs, by Chris Paul, Joyce & Paul PLLC, Tulsa, Oklahoma, USA.

Pipeline integrity programs carry with them inherent legal issues and exposures: a meaningful integrity program will – by its very nature – be self-critical. The processes involved in evaluating pipeline systems may not only result in the positive outcome of increasing pipeline safety, but may also result in creation of data and documentation that, if misused or viewed with the wisdom critics find in hindsight, could provide a roadmap for plaintiff attorneys or government investigators to question an operator’s decisions in the event of an accident. These issues are all the more problematic when it is also recognised that there is a need for involving third parties in consulting arrangements and contracts for internal inspections, thus making data and documentation control more challenging. Also, management of documents that are provided to the government on integrity issues are subject to release to the public, raising security issues as well as putting information at increased risk of being used against the organisation in enforcement or litigation proceedings.

Using a US-based viewpoint, the author reviews the legal issues and the demands that pipeline integrity programs place upon operators, which include data integration and records retention requirements, and it includes a discussion of how these issues and demands may result in misinterpretation and misuse of data and documents. The bases for management and company exposure are discussed, as are the criteria used by the government for determining whether information within the knowledge of the company might result not only in simple liability, but also the possibility of criminal exposure.

Mr Paul reviews solutions to these legal issues, including how to deal with improved ILI tools, which provide tremendous amounts of data that must be captured and integrated with other information involving the operator’s pipeline systems. It is emphasised that while companies want to do the right thing, they need to understand the legal risks involved so that they can do the right thing in the right way. The author makes the critically important point that companies who are legitimately and thoroughly trying to identify, qualify, quantify, and manage risks must understand how to handle documentation associated with their integrity programs.