WHAT EFFECT DO GEOHAZARDS HAVE ON PIPELINES?
Geohazards can lead to pipeline movement and high associated strains. Understanding how the strains in a pipeline have changed due to landslide loads, settlement, etc., is vital for safe operation. High-resolution pipeline mapping services help pipeline operators identify and assess the following pipeline threats and defects.
Find out more about the different pipeline threats and defects below.
Pipelines contain bends that were formed during manufacturing (fabricated bends) and construction (field bends). The stresses and strains associated with these are considered during the design of the pipeline. However, additional loads applied during construction or in service can introduce unwanted bending that results in stresses or strains that may exceed safe limits. Compressive stresses on the inside of a bend can lead to localized buckling and wrinkling and tensile stresses on the outside of a bend can lead to fracture, especially in the presence of an anomaly in the pipe wall, such as circumferential cracking. Bending loads can be caused in many ways, for example landslides, ground settlement, thermal expansion, as well as third-party activity, ground movement due to construction works or frost heave.
Geotechnical events near pipelines, such as landslides or earthquakes, can result in pipeline movement. In other words the pipeline can move from its original position, be affected by additional stresses and anomalies such as wrinkles may be formed. Knowing that the pipeline shape has changed, that its curvature has increased or decreased and detecting anomalies caused by geohazards is crucial for the safe operation.
Wrinkles are localized waveform deformations in the pipe wall, typically consisting of several alternating inward and outward bulges and caused by excessive bending loads. The distance between the peak and the trough of the outward and inward bulges is greater for wrinkles than for ripples.
You can find information about pipeline geometry deformations like dents, ovalities or buckles here.
A Holistic Approach
Given the unpredictability of nature’s movements, amongst other things, each pipeline mapping endeavor is unique. The most effective way to assess changes in shape and movement is to approach pipeline mapping comprehensively.
The ROSEN Group joins current industry best practices and the most advanced pipeline mapping inspection solutions with the knowledge of subject-matter experts to enable pipeline operators to make the best possible integrity management decisions. ROSEN supports operators beyond short-term decisions and provides management plans and training to enable them to take the right maintenance actions at the right time in order to extend the life, safety and performance of their pipelines.
PIPELINE MAPPING TECHNOLOGIES
The ROSEN Group uses a high-resolution pipeline mapping technology that provides accurate information about the pipeline route. Paired with a variety of integrity assessments the following technology helps to manage the risk posed by geohazards. Paired with a variety of integrity assessments the following technology helps to manage the risk posed by geohazards.
XYZ Mapping and Routing Technology
XYZ technology uses an integrated Fiber Optic Gyroscope (iFOG) and micro-electronic mechanical systems (MEMS) to provide precise location and pipeline curvature data that can be used in the operator’s pipeline GIS, stress modelling and pipeline movement analyses.
Especially when original construction drawings are not available, the XYZ technology is a cost-effective way of accurately establishing the pipeline route. The tool can run through remote and inaccessible areas where conventional above-ground mapping surveys are challenging.
In addition, XYZ data not only provides information about the pipeline’s position and centerline, but also serves as the basis for performing bending strain and pipeline movement assessments.
Pipeline mapping services can be especially important when it comes to detecting areas where the pipeline may have been affected by ground movements such as landslides. In combination with other in-line inspection services such as XT and MD tools, the RoGeo XYZ service provides critical data necessary to properly address movement related anomalies such as pipeline buckles. Ground movement or erosion can also result in a reduced depth of cover which in turn can increase the pipeline’s susceptibility to third-party damage. ROSEN’s depth of cover service uses a combination of XYZ mapping data and above ground profiling data to quantify depth of cover and help manage the associated threats.
The XYZ pipeline mapping tool facilitates a wide range of related services including
- In-field location of anomalies
- Diagnosis of pipeline damage
- Identification of pipeline movement
- Bending strain analysis
We know that pipeline inspection and engineering assessment must go hand in hand. Therefore, a broad range of assessment services complement high-end inspection technologies. The combination of inspection and assessment reduces uncertainty, thereby increasing safety, and minimizing cost.
BENDING STRAIN ASSESSMENT
Geohazards represent a major threat to pipelines because the resulting loading can be hard to identify, difficult to predict, and extremely challenging to control. Abnormal loadings can result in damage to, or even failure of, the pipeline from tensile fracture or buckling.
It is possible to determine the magnitude of the threats posed by ground movement and provide comprehensive assessments that can be acted upon by asset owners. The vertical and horizontal profile information gathered by an XYZ tool can be analyzed to identify areas of suspicious pipeline bending that is not related to factory or field bends.
Bending strains in these locations can be quantified and then compared against critical strain limits. Both compressive and tensile strain limits can be determined for individual pipelines to ensure that bending loads do not threaten the immediate or long-term integrity. The assessment can also take account of other anomalies that have been identified on the pipeline within an area of bending strain, such as cracking or corrosion.
Where initial assessments indicate a significant threat from bending strain, more targeted analysis and assessment can be performed, supported by geotechnical specialists, in order to investigate the potential source of additional loading and the stability of the area. Where appropriate, Level 3 assessments can be performed to model the full stress condition of the pipeline using finite element analysis and appropriate soil models.
PIPELINE MOVEMENT SERVICES
Once the pipeline route has been accurately mapped and areas of bending strain have been identified, the geohazard threats can be monitored through repeated inspections and comparison of the reported position of the pipeline. Pipeline movement can be monitored by comparing XYZ data from several pipeline mapping inspections which then allows changes in the pipeline loading conditions to be investigated. Where pipeline movement is identified, further investigations may be required – in some instances using a localized site investigation – to establish the cause of the movement and the associated rate of change. ROSEN can offer advice on what surveys and measurements are appropriate to manage the ongoing geohazard threat.
Third-party interference is widely documented as being a major cause of pipeline failures, often leading to rupture and extensive hydrocarbon releases. This type of damage is caused by human interference from activities such as construction. The susceptibility of a pipeline to third-party damage is dependent on many factors, one of which is its burial depth. A depth-of-cover assessment ensures that the burial depth is sufficient to manage pipeline safety and comply with local, state, and federal regulations. To determine the depth of cover over an entire pipeline, we use a methodology that combines ground elevation data with high-resolution data collected during an in-line inspection (ILI). This is done using the RoGeo XYZ service, which includes an optimized Inertial Measurement Unit (IMU) that accurately measures the position of the tool within the pipeline. This methodology enables operators to review the depth of cover on the entire pipeline and identify locations not meeting the minimum requirements.
The pipeline geohazard service is a pipeline GIS-based service for pipeline operators to gain better insight into geohazards that threaten the integrity of their onshore or offshore pipelines.
Route screening provides an overall picture of the geohazard threats along the pipeline. This is done, using various datasets and employing data mining and analytics, i.e. spatial data from digital elevation models, soil and land cover datasets, rainfall and river data, earthquake data, etc. Our geohazard service is proactive and delivers accurate quantitative results, so pipeline operators know exactly what areas are of concern and what risks are involved. This enables them to better prioritize pipeline inspection efforts.
PIPEDRIFT SCREENING SERVICE
It is not only possible to combine a XYZ pipeline mapping service with some in-line inspection tools, but also with pipeline cleaning tools.
The PipeDrift Screening Service provides a cost-effective option for regularly monitoring pipelines susceptible to movement by using a cleaning tool containing an Inertial Measurement Unit (IMU). In this way, repetitive screening inspections enable the pipeline operators to detect pipeline movement at the earliest stage, so that they can distinguish stable areas from dynamic ground movements and monitor the progress of any pipeline movement. This enables timely planning of countermeasures.
Once the in-line inspection data is available, analyzed and assessed, the pipeline operators are able to make short-term decisions to ensure the performance, lifetime and safety of their pipeline. Even after these short-term decisions, ROSEN supports with a proactive and forward-looking approach.
Pulling all the pieces together creates a robust, justifiable management plan that delivers the optimum combination of activities (in-line inspections, integrity assessments, etc.) to ensure safety. A plan like this allows pipeline operators to take the right maintenance steps at the right time in order to extend the lifetime, safety and performance of their pipelines.
A basic prerequisite for the quick and reliable assessment of an asset’s integrity is the availability of consistent and fully aligned datasets. Additionally, more and more regulations now require that all pipeline records be traceable, verifiable and complete.
However, with the amounts of collected data steadily growing, the establishment of a system of record where all available data is readily accessible is becoming an increasingly critical issue for pipeline operators.
Competence is a key consideration in managing pipeline assets. The risks they present – and the safety of people and the environment – are becoming more imminent. Plus, standards and regulations explicitly require all personnel to be competent and qualified in their respective fields of responsibility. Understanding this need, ROSEN has developed training courses, education programs and qualifications specific to addressing threats.
Find out more about Competence Training