Corrosion growth analysis
Corrosion of metal is a long-standing problem in a wide range of industries including oil and gas. Pipeline operators are faced with questions about the presence, location, and severity of corrosion in their pipelines. In addition, many challenges arise estimating a realistic corrosion growth rate.
The corrosion growth can be determine by one of the following methods:
- Half life
- Comparison of 2 ILI dataset
An overly conservative corrosion growth rate can lead to inspecting the pipeline more frequently than needed, additional required and costly excavations, as well as inaccurate modeling and forecasting within a risk program.
One way to gain an understanding of pipeline condition and degradation rates is by performing an in-line inspection (ILI) of a pipeline. This ILI will report the axial and circumferential location of detected corrosion anomalies including the severity of the anomaly in the form of depth, length, and width. In case of 2 inspections a corrosion growth rate can be calculated based on the change in depth of the same individual corrosion anomaly divided by the time between the two inspections.
Often the inspections are carried out with different tools/ different technologies / different direction with varying capabilities to interpret different cases of corrosion. The pipeline may have been repaired and/or re-routed between the inspections leading to a need for substantial adjustments in the data.
Our standard Pipeline Manager software can make all the needed adjustments, typically using all the weld positions for reconciliation of distances and direction. In the second phase, Intero uses additional in-house software to match defects from two inspections. This software uses algorithms based on both defect position and size with flexible weightings. The upper limits determined are projected forward to produce potential worst-case defect sizing in the future.
Advantages
- Reliable corrosion rate distribution for determining long-term management strategies
- Highlighting any areas with high CGR
- Best basis for remaining life assessment