Holistic approach yields better data and optimizes technology
Offshore operators often fail to fully benefit from their pipeline inspection programs. In so doing, they are effectively leaving money on the table, because an effective pipeline integrity management system (PIMS) captures all the benefits of an inspection and enhances the value of an asset throughout its lifecycle.
A well designed and managed pipeline integrity program reduces scheduled and unscheduled downtime and improves HSE performance. It also helps to assure greater value for money on inspection and maintenance programs; yields auditable data to demonstrate regulatory and internal compliance; drives a more efficient stewardship of assets and resources; improves risk management and preparedness; enhances corporate governance; and promotes operational confidence.
At the bottom line, it helps to increase uptime and productivity, extend the life of pipeline assets and significantly improves business performance and the return on investment.
The costs associated with pipeline failures or unplanned shutdowns are high in terms of lost production and repairs. HSE problems can raise those costs to another level. A fully implemented PIMS can prevent many of the failures, incidents, and shutdowns that typically occur on less well-managed pipelines. Distilled to its essence, PIMS is a comprehensive risk-assessment program.
The general categories of risk for offshore pipelines are well known and documented in a study prepared for the U.S. Minerals Management Service in 2000 and in the PARLOC studies in the North Sea. These studies analyzed thousands of incidents – involving hazardous liquid and natural gas pipelines, including risers and other components – that occurred between 1984 and 2000. The principal causes of these incidents were internal and external corrosion, material defects, defects from construction or installation, equipment malfunction, operator error, and damage from outside forces. These risks all can be mitigated by managing the integrity of the pipeline, provided they are accurately identified and assessed.
|This picture, from an ROV inspection in the Gulf of Mexico, shows anode wastage with approximately 50% deterioration. A pipeline integrity management system (PIMS) captures all the benefits of an inspection and enhances the value of an asset throughout its lifecycle.|
While risk assessment can be conducted at any time during a pipeline's operational life, and becomes a continuous process in an ongoing PIMS program, it is most effective when started during the design stage. Risks identified during the design stage can be mitigated or eliminated with modifications that also reduce future operating costs.
Strategies also can be developed for managing any additional risks. For example, careful monitoring of risks during construction and installation will help to ensure that the condition of the pipeline is thoroughly documented when it is commissioned and put into service. A complete dossier of accurate data about a pipeline's design, startup condition, and subsequent operational history is of great value when setting up and operating an effective PIMS.
Risk assessment is also the starting point for establishing a PIMS for operational pipelines, following the same methods used for new pipelines. The process begins with a review of the design and condition data, such as inspection and maintenance reports, as well as operating procedures and HSE systems. Further inspections and testing may be needed for a complete baseline condition profile. Gap analysis then pinpoints vulnerabilities and deficiencies, and also identifies strengths, which are built upon. This is followed by an assessment of the probability and consequences of every potential failure, which may be conducted with the assistance of risk-based mechanical integrity (RBMI) software. The results are summarized in a probability/consequence matrix that clearly ranks each risk. These rankings are used to determine inspection and maintenance priorities and to recommend changes in operating and management procedures. The areas of risk that present a high probability of failure with severe consequences are flagged for diligent monitoring and a higher frequency of inspections, perhaps using sophisticated technologies. Risks with a low probability of occurrence and minor consequences simply may be ignored until a failure occurs.
Risk assessment findings may lead to recommendations for bespoke inspection programs. For a new pipeline, the assessment will yield clear risk rankings and inspection priorities, along with a highly optimized frequency schedule. An in-service pipeline that lacks adequate documentation of its operations could make risk rankings problematic, so more frequent inspections may be required.
As the operator gains confidence in the data, the inspection program can be optimized. Where good documentation is available for an existing pipeline, including complete inspection records, the information will support risk rankings that allow optimization, which in some cases may lower inspection frequency or alter the techniques used.
There is no universally recognized standard for offshore pipeline inspection programs and the overall safety management of pipeline systems. Regulatory agencies in various regions require operators to prove initially that a pipeline is safe and fit for purpose and to report certain information, such as results of cathodic protection tests, at regular intervals. Otherwise, the inspection and maintenance of offshore pipelines is left to the discretion of individual operators. It is thus essential that operators understand their risks, assess and rank them accurately, and establish inspection programs that use the right methods and tools to yield data that represent the conditions of their pipelines.
Pipeline integrity is commonly viewed as a technical matter mainly involving inspections. The available technology is impressive. Sophisticated flow modeling and probabilistic analysis are available for risk assessment. Intelligent pigs snake though pipelines carrying many highly sensitive instruments. Remotely operated vehicles fly along risers and pipeline routes to look for coating damage, external corrosion, leakage, scour and spanning, while also gathering side-scan sonar images. Chemical analysis of effluent can detect evidence of corrosion if pigging is not possible.
Yet the results often do not reflect the state-of-the-art technology we employ to assess risks and determine the condition of our pipelines. The number of failures and incidents remains stubbornly high. If it were mainly a matter of technology, the advances should have brought similar improvements.
Experience suggests that how the technology is used and managed plays a critical role. To achieve the best results, we must fully understand what data we need, select the right tools and procedures to obtain it, interpret it correctly, act upon the findings, and use the lessons learned to improve our PIMS performance. All of this requires a level of expertise that lies outside the core competencies of many pipeline operators.
Pipeline inspection is often seen as a costly imposition done mainly to satisfy regulatory or internal corporate demands – in other words, to put a check in a box. Only findings of serious defects prompt further action. This short-term mindset fails to see inspections as a vital part of a comprehensive process to maintain the long-term integrity of the pipeline – its continuing availability and fitness for service. In the absence of serious defects, the inspection results are consigned to a shelf without further review and never again consulted.
Offshore pipeline inspection can be expensive. ROV visual inspection usually requires support vessels, with attendant day rates. Inspections performed as an exercise without commitment to pipeline integrity are simply wasteful.
Using intelligent pigs and instrumented ROVs in this context may provide a feeling of assurance. But, in reality, it can simply amplify the waste. Even a carefully optimized inspection program can be wasteful if the data is used only to assess a pipeline's condition. We should get more from our efforts than a check in a box and a binder on a shelf.
Integrity management can increase the value of the investment in monitoring, inspecting, and maintaining pipelines. The PIMS perspective is comprehensive and long-term. Since the integrity of a system involves each individual component, PIMS evaluation and monitoring covers every part and piece of equipment associated with a pipeline – pig launchers and receivers, metering skids, instrumentation and controls, structural supports, welds and connectors, and coatings. Operating and environmental factors such as fluid composition, the flow regime and throughput volumes, the potential for fluid accumulation and slugging, seabed topography, seawater temperature, salinity and oxygen content, and the strength of currents are all considered in assessing risks and are then monitored for changes.
Measurement and analysis are not limited to physical components and environmental factors in a PIM program. All aspects of how a pipeline system is operated and managed are scrutinized to identify elements of risk and opportunities for improvement. HSE policies and procedures are closely analyzed and many other factors that affect system integrity are also considered, including hiring qualifications and personnel training, compensation and incentives, supervisory organization and approach, data collection and documentation, and even supply chain and contractor management. Gaps and deficiencies identified in these and other areas represent opportunities to further reduce risk and improve performance.
Diligence and continuity
The area where a PIMS can have the greatest positive impact, however, is in the quality of inspection data and its beneficial uses. In many instances, inspections do not target the areas that will yield the most useful data. Or if they do, the tools or techniques may not be the best ones to measure those parameters accurately; or the instrumentation may not be calibrated correctly to provide measurements within a useful range of tolerances. Optimizing the inspection process for data quality and utility demands a level of expertise that may be difficult for individual pipeline operators to maintain. In such cases, it often is worth the effort and expense to bring in a qualified consultant.
Securing appropriate and accurate inspection data remains just a technical exercise, however, if the data is not used to maximum benefit. Putting the data to good use is part of the comprehensive nature of a sound integrity management program. Spotting defects and impending accidents is, of course, primary and of urgent importance. This information, particularly if it can be reviewed in the context of previous inspection records, will determine whether remedial or mitigating actions are required. If no actionable defects are found, the data provides proof to senior management, regulators, and other stakeholders that the pipeline remains fit for purpose.
When current data is then added to the historical record of the pipeline's condition going back to the inauguration of the PIMS, the continuous record can be used to reassess risks and to confirm or modify risk rankings. It also can be used to assess the PIMS' performance and determine whether it should be adjusted or changed. A lengthening record of clean inspections may allow for beneficial changes in operating parameters and procedures or a relaxed inspection frequency, measures that lower costs. Reducing an annual visual ROV inspection to biannual, for example, could save hundreds of thousands of dollars. Changes of this sort, however, can only be justified by a continuous data record.
Diligence and continuity are key aspects of a successful PIM program. Details must receive due attention. Records must be thorough and complete. Confidence based on poorly managed inspections is always over-confidence. Failure to review and maintain data continuously will ultimately compromise the ongoing inspection process so that it loses much of its value and further effort is wasted.
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