For pipeline assets, these expectations are addressed through the implementation of a pipeline integrity-management program, however, until recently the ability to collect high-density and high-quality data sets to validate these programs has not been possible in conventionally unpiggable pipelines. The introduction of a new generation of intelligent pigging technologies such as Quest Integrity Group’s InVistaTM tools has enabled high-fidelity ultrasonic data sets to be collected in previously difficult-to-inspect or unpiggable pipelines. This article discusses the impact that such inspection and assessment tools have had on best practice implementation of pipeline integrity management programs for previously unpiggable pipelines.
Pipeline integrity management systems for difficult or unpiggable pipelines
The development of a pipeline integrity management system requires the definition of potential failure modes and their likely consequence and associated risk. Where there is a greater-than-negligible risk of a specific failure mode, a maintenance program is actioned that is aimed at mitigating the specific risk to a level that is as low as reasonably practical. Another important component of a pipeline integrity-management system is validation procedures to verify the integrity status of a pipeline, and where appropriate, facilitate a predictive engineering assessment that can be used to modify the maintenance plan. This typically involves acquisition of inspection data from the pipeline and the application of specific predictive mechanical or corrosion damage models and pipeline integrity assurance codes. Many ageing pipelines, laterals, and even some new systems were not designed to be inspected with conventional intelligent pigging technologies. Consequently, the impact of not being able to validate integrity status by this means has an appreciable impact on the confidence an operator has in the effectiveness of the maintenance plan.
In recent years, this has been an area of significant concern and increased focus has been placed on making conventionally unpiggable lines piggable. Often this has involved pipeline modification, however, in many cases this approach is either unfeasible from an engineering standpoint or is associated with very high cost and operational penalties.
Quest Integrity’s InVista inline inspection tool is designed for the inspection of lines that cannot be inspected with conventional intelligent pigs. Not only does this tool collect high-resolution ultrasonic geometry and metal loss data sets in the same pass, but the unique design of the pig allows it to negotiate 1.0 D bends, mitre bends, unbarred tees and other restrictions that have not been possible in the past. In addition, conventional launcher and receiver facilities are not required. This is a significant advantage in situations where design, engineering or space constraints are present.
InVista case study
Offshore pipelines can be challenging to inspect due to limited launcher/receiver facilities, space constraints and/or limited accessibility. Quest Integrity recently inspected a DN150 offshore pipeline with no permanent traps using its InVista in-line inspection tool. The infield pipeline runs between the wellhead and production platform. After only two foam pig cleaning runs, 99.6 per cent of the wall thickness data was successfully collected, identifying two external metal loss anomalies, three internal metal loss anomalies and three dents.
The InVista tool’s light weight and short length allowed small temporary traps to be installed in the limited space available. This meant no hot work or permanent alterations were needed. This benefit, as well as the geometry and wall thickness data being provided in a single run, resulted in significant cost savings for the operator.
Additionally, a fully integrated, AS2885 and API 579-compliant Level 2 FFS assessment was included providing the client with a comprehensive overview of its pipeline’s integrity.
LifeQuestTM pipeline and advanced assessment
For pipelines, FFS assessment has traditionally focused on establishing whether a particular defect exceeds established criteria for safe and reliable pipeline operation. These assessments have historically been performed on a defect-by-defect basis in conjunction with field verification (“˜prove-up’) studies and are known to be computationally intense.
Recent advances in analytical software and computing power make it possible to perform sophisticated FFS assessments rapidly on the entire pipeline using complete inline inspection data sets, making it possible to use some forms of FFS assessment as a screening tool prior to field verification, as well as an evaluation tool for pre- and post-remediation of defects.
Quest Integrity’s LifeQuestTM software suite anchors a four-step model consisting of inspection, data analysis, advanced engineering and remaining life assessment that helps clients to manage the lifecycle value of their pipelines.
For more information, visit www.questintegrity.com
