Onshore and offshore pipelines are expected to operate safely and reliably in various harsh and remote environments, as well as in high consequence and often populated areas. Provided that pipelines are designed, constructed, and maintained in accordance with recognised standards, their operation will likely remain safe and secure.
When this is not the case, failures may occur at any time during the operational life of a pipeline, though the likelihood of failure will inevitably increase as the pipeline ages due to time-dependent degradation (e.g., internal, and external corrosion). As pipelines are increasingly operated beyond their original design life, it stands to reason that the level of integrity of such lines will have deteriorated.
In some regulated regions, a pipeline may only be operated beyond its original design life following the completion of a formal life extension study, e.g. in accordance with ISO/TS 12747 or NORSOK Y-002. However, formal life extension remains a useful tool regardless of whether it is mandated by law, providing significant benefits including a broad range of economic, technical, social, and environmental effects.
This article focuses on addressing the following questions:
- What are the main challenges with pipeline integrity management for aged assets?
- When should a pipeline be retired from service?
- How do you extend the remaining life of an aged pipeline asset and what are the benefits?
PIPELINE INTEGRITY MANAGEMENT CHALLENGES FOR AGED ASSETS
As pipelines age, the likelihood of failure will inevitably increase as a result of time-dependent damage mechanisms (e.g., corrosion, fatigue, etc.). The statement is generally true for any load-bearing structure. However, in the context of pipeline integrity management, assessing and understanding time-dependent degradation may be further complicated by less tangible effects of factors including poor data management, changes in operating conditions, effectiveness of corrosion controls, and so on.
For example, a pipeline operating beyond its original design life may have performed without any known issues for many years, having been operated in accordance with well-established and clearly defined monitoring and maintenance protocols. The perception may be that the pipeline in its current state is of sound condition. Inspection of the pipeline may have even been used to validate the immediate integrity of the pipeline. However, what of the future integrity? How long can the pipeline continue to operate safely? What will be the cost of future repairs?
In the experience of AIE, it is unfortunately too common for pipelines to be operated with a perception of integrity, or for operators to focus too heavily on immediate integrity without due consideration for the remaining life of the pipeline or how proactive measures may be used to prolong its remaining life and avoid costly unplanned shutdowns. Even when an assessment of future integrity (i.e., remaining life) is available, the basis of such assessments is all too often left unchallenged and the result taken as fact, without the appropriate level of scrutiny that is warranted to establish its validity.
A holistic approach is therefore required to understand historical changes in pipeline operating conditions, the basis on which existing corrosion controls were developed and whether such controls remain effective. This is not only critical to understand the current and future risk profile of the pipeline, but also to support optimised integrity controls and support future budget planning.
PIPELINE END-OF-LIFE MANAGEMENT
Traditionally, end-of-life management is associated with the retirement of an operational pipeline and planning for decommissioning or replacement.
So, when should a pipeline be retired from service? A pipeline may be removed from service for any number of reasons, though typically these tend to be cost or risk-related, i.e. operation of the pipeline is no longer economically viable, or the pipeline poses an intolerable health, safety, business or environmental risk.
More recently, continued operation past the design life of existing infrastructure has become increasingly popular due to recoverable oil and gas reserves remaining beyond the pipeline original design life, or where there are new fields that have been developed and tied into an existing pipeline system.
Where the need to operate a pipeline beyond its original design life has been established, a life extension study may be used to demonstrate the feasibility of continued safe and reliable operation of the existing pipeline system or provide a basis on which operation could be continued. Where appropriate, this may be further supplemented by life-cycle costs-risk-benefit analyses to determine an optimised inspection, maintenance and/or replacement strategy. The assertion being that aged pipelines (or sections thereof) may require a higher level of management funding to maintain a suitable level of safety relative to that for a new pipeline.
PIPELINE LIFE EXTENSION
The design life of a pipeline is established to avoid failure occurring during a finite period of pipeline operation as a result of time-dependent degradation mechanisms, assuming a certain level of maintenance is performed. Exceeding the design life does not necessarily mean that the pipeline is no longer fit-for-purpose, but the basis for operating a pipeline beyond the design life should be formally documented in the form of a life extension study.
How do you extend the remaining life of an aged pipeline asset? A generic and high-level life extension process is outlined in Figure 1. A summary of key components that should be included in the life extension evaluation is also provided below:
- Immediate integrity (fitness-for-purpose) and remnant life assessment (e.g., based on inline inspection or direct assessment)
- Gap analysis to identify additional requirements of current design codes and regulations
- Status and condition review of safety systems
- Risk assessment for the extended period
Figure 1 Life Extension Process
Additionally, the life extension study may be used as an opportunity to audit the existing Pipeline Integrity Management System (PIMS). This may be critical to establish the adequacy of existing processes and procedures and determine whether written procedures are being followed correctly. Furthermore, the audit may be used to assess and verify the technical qualification of and any legacy integrity controls and confirm these remain effective.
AIE PIPELINE SERVICES AND SOFTWARE
AIE works to support numerous key clients in the MENA and Southeast Asia region to improve operational reliability, safety, and asset protection whilst also helping to maximise plant efficiency and mitigate the constant operational challenges and hazards facing heavy industries such as Oil and Gas, Power Generation and Mining.
We are an independent and highly skilled integrity services provider, possessing the necessary specialised knowledge and experience to support all aspects of pipeline life extension and integrity management. We offer a holistic approach to pipeline integrity and fitness-for-service (FFS) assessment, risk assessments and all PIMS-related activities.
Comprehensive and assured pipeline integrity management
AIE has developed a web-based pipeline integrity management platform, Veracity Pipeline, which offers a user-friendly and systematic approach to pipeline risk assessment and management. Veracity Pipeline forms an integral part of the operators’ Pipeline Integrity Management System (PIMS). Its structure and design are fully compliant with industry codes and best practice engineering standards.
To learn more on how our highly skilled pipeline professionals can support your pipeline life extension and integrity management requirements, please visit our Contact Us page.
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