Although the genesis of OneBridge Solutions (OBS) stemmed from meeting the challenge of aligning and analyzing inline inspection data, it soon became clear that this was just one of many data analysis problems to solve within the pipeline integrity space. Inline inspection can present a comprehensive understanding of a pipeline’s corrosion at that point in time, however monitoring corrosion control measures like cathodic protection can determine how well a pipeline can prevent external corrosion from happening in the first place.
Intro to CP and CIS
Cathodic protection (CP) is often utilized or required to provide protection to pipelines and help prevent external corrosion on a metallic pipeline. To ensure the proper amount of cathodic protection is being applied, CP surveys are performed to quantify the specific level of “protection” that the pipeline has against external corrosion. This is done by taking “CP readings” at various points along the pipeline.
CP readings are values that quantify a pipeline’s potential with respect to a reference metal. It is sometimes referred to as a pipe-to-soil (P/S) reading because it’s measured between the pipeline and the soil. Because corrosion is an electrochemical process, measuring the pipeline potential can indicate whether the pipeline will act as a cathode and corrode in its surrounding environment. Typically, the potential of the pipeline needs to be more negative than the pipeline’s natural potential, to ensure corrosion is not occurring.
A close interval survey (CIS), also referred to as a close interval potential survey (CIPS), consists of measuring the pipeline’s potential at close intervals e.g. every 3 feet. These readings are taken as the inspection crew walks the centerline of the buried pipeline. Typically, the readings are taken when the rectifiers (utilized in an impressed CP system) are off. These readings are referred to as P/S Off or (Instant) Off readings.
Because CIS requires a technician physically walking the pipeline, taking readings every few feet while also interrupting rectifiers to do so, CIS tends to be quite a time-consuming undertaking. Ensuring that useful information is gleaned from this data is paramount.
External Corrosion Module
In a follow-up to our blog post on Atmospheric Corrosion Digital Reports, which discussed the phased development of a new External Corrosion module, Phase 1 is nearing completion. Soon CIM users will be able to analyze their CIS data within this new module, utilizing a similar workflow to ILI analysis.
Of particular interest to OBS’s clients is the correlation of different data sets e.g. external corrosion surveys with inline inspection reports while also providing a more advanced analysis of these external corrosion surveys to fully harness the value from these time intensive surveys.
How does cathodic protection (CP) correlate with corrosion detected from ILI? Where do depressed CP readings indicate interference? What is the root cause of external corrosion in a particular region? With CIM’s External Corrosion Module (ECM), we may be closer to answering these critical questions.
CIS Workflow
The embedded workflow for the External Corrosion Module allows for the comprehensive management of your external corrosion control program:
- Ingest and Align: CIS data is imported and aligned with centerlines provided by your GIS and inline inspections as well as previous close interval surveys.
- Analyze: CIS readings are reviewed and analyzed using criteria of the user’s choosing. This criterion includes those determined by industry standards e.g. identify all areas that are more positive than -850 mV, as well as advanced criteria determined by our Data Science team.
- Identify Actions: group consecutive areas that meet specified criteria into regions, allowing users to select regions needing mitigation and generate mitigation plans for field personnel.
- Mitigation Tracking: record field notes, work order numbers, and important dates for all mitigated locations, along with audit reporting to provide record of completed tasks and ensure closure of the assessment cycle.
What’s Next
- Integrating and aligning additional external corrosion data sets i.e. CP surveys, DCVG and ACVG to gain a more holistic understanding of the external corrosion threat.
- Advanced data analysis that includes highlighting significant changes in CP readings year-to-year.
- Harness the power of data science and machine learning to determine the root cause of external corrosion as well as identify areas of potential CP interference.
Like how CIM utilizes data science and machine learning to analyze inline inspection results or determine areas of active internal corrosion, advanced data analytics can be harnessed to better understand and interpret your external corrosion surveys, ensuring valuable information is gleaned from your data.
Contact us to learn more.
