Current risk assessment practice in pipeline integrity management tends to use semi-quantitative index-based or model-based methodologies. This approach has been found to be very flexible and provide useful results for identifying high-risk areas and for prioritizing physical integrity assessments. However, as pipeline operators progressively adopt an operating strategy of continual risk reduction with a view to minimizing total expenditures within safety, environmental, and reliability constraints, the need for quantitative assessments of risk levels is becoming evident. Whereas reliability-based quantitative risk assessments can be and are routinely carried out on a site-specific basis, they require significant amounts of quantitative data for the results to be meaningful. This need for detailed and reliable data tends to make these methods unwieldy for system-wide risk assessment applications. This paper describes methods for estimating risk quantitatively through the calibration of semi-quantitative estimates to failure rates for peer pipeline systems. By applying point value probabilities to the failure rates, deterministic quantitative risk assessment (QRA) provide greater rigor and objectivity than can usually be achieved through the implementation of semi-quantitative risk assessment results. The method permits a fully quantitative approach to suit the operator’s data availability and quality, and analysis needs. The paper also discusses experiences of implementing this type of risk model in Pipeline Integrity Management System (PIMS) software and the use of and integration of data via existing pipeline geographical information systems (GIS).
Objective/Scope Managing the long term integrity of a critical 10″ subsea crude oil pipeline is dependent on being able to use the correct inspection technologies, however, the current structure of the pipeline does not allow for any in-line inspections. Consequently managing the short term integrity of the pipeline becomes a priority until the pipeline is made piggable. This paper describes where and how to investigate along the pipeline to determine the current internal condition of the pipeline. Methods/Procedures/Process A desktop feasibility study was completed in order to determine the locations and the confidence in the use of an external ultrasonic scanning survey (auto-UT) to determine the short term integrity of the pipeline. This comprised the following: Technical identification of the points along the length of the pipeline that is most susceptible to internal corrosion.Confidence in evaluating condition of pipeline based on auto-UT In addition a review of the current sacrificial anode protection of the pipeline was completed to ensure that any investigative works completed would not result in any external corrosion issues. Results/Observations/Conclusions For a product velocity of 0.28m/s, using the approach in NACE SP0208 (Appendix A), an inclination angle of 2° is critical for water accumulation. Review of the vertical profile of the pipeline indicated that there are nine sections exhibiting critical angle in excess of 2°. In addition 4 further sections of the pipeline are characterised by long inclines which could also contribute to water separation from the oil-water emulsion. Further consideration was given to sections of the pipeline where solid accumulation was possible, as this may aggravate internal corrosion. As the pipeline is practically straight in the horizontal plane (from bottom of riser) to the tee connection with a 20″ export pipeline, there are no additional pipeline fittings (dead legs) with the exception of a 10″ tap assembly to allow product into the 20″ pipeline. Auto-UT provides highly accurate wall thickness measurement and a defect resolution from 1mm x 1mm. All measurements are recorded in millimetres and repeated inspections at the same location provide most accurate corrosion growth rates. The main concern with auto-UT is that it does not provide information on the condition of the whole pipeline, only for the area of pipeline covered by the auto-UT. This limitation has to be overcome with a correct choice of the locations to be inspected. Novel/Additive Information This paper describes the thought processes that must be undertaken when considering the short term integrity of an unpiggable pipeline: the likelihood and expected types of corrosion existing within,the likely locations, most susceptible for corrosion to occur andthe benefits of using various inspection technologies to determine both the short and long term integrity of the pipeline.
This paper is a case study on developing and implementing a pipeline integrity management system (PIMS) for a medium-enterprise operator in the Middle East. It explains the stepwise, collaborative, applied learning approach adopted by the operator’s focus group that helped to show the value proposition of the system to higher management at each phase. It further explains how this approach subsequently acted as a catalyst between project phases resulting in an operational risk-based PIMS. PIMS must address elements such as people (organized team of various disciplines contributing to the overall objective i.e. pipeline integrity management), process (standards, procedures, and policies on how to achieve the objective) and tools (resources to achieve the objective) to manage pipeline integrity. This paper describes the way BHGE (the consultant) and the operator have worked together and adopted a stepwise approach to address these elements to setup a PIMS within the constraints of a limited budget. The process consisted of PIMS gap analysis, development of PIMS manual and procedures and Excel-based comprehensive, semi-quantitative risk assessment, and is based on an effective contracting strategy that resulted in use of the PIMS consultant as a trusted partner. Pipeline operators fall into three common categories with respect to PIMS implementation: (1) those with large pipeline networks and substantial budgets for integrity management, (2) those with relatively small pipeline networks but relatively high integrity management budgets due to business-critical pipelines being part of the network, (3) those with a relatively small pipeline network and correspondingly small integrity management budget. This paper focuses on this third category of operators. Many challenges arise while implementing an integrity management system in any operation. This paper highlights these challenges and how they were resolved through knowledge transfer, a technical workshop, and an astute contracting strategy. It explains how the subject-matter experts (SMEs) from the consultant were used to manage the pipeline network through a risk-based approach before investing in in-house software tools and personnel. It also highlights the importance of a pilot phase which results in a detailed understanding of the scope and organization-specific requirements before deciding on major capital investment. It further explains how knowledge transfer and a cooperative relationship resulted in various stakeholders for the operator becoming brand advocates for the system. Also, the paper explains the practical steps adopted in setting up risk-based PIMS with a limited budget and how that could be used as a road map for other small-or medium-enterprise operators. And finally, it elaborates on the role played by the applied learning approach, knowledge transfer, inclusive relationships, a smart contracting strategy, and use of the consultant as a trusted partner to implement a risk-based PIMS with limited investment.
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