A Phased Path to Pipeline Integrity
Each phase builds on the last, combining advanced inspection techniques and targeted excavation to identify, assess, and mitigate corrosion risks in high-consequence areas.Phase I: Mapping the Pipeline with Precision
Phase I included pre-assessment surveys utilizing PCMX signal attenuation tools, existing as-built drawings, and GIS overlays to accurately locate pipeline alignments. Survey stakes were installed at 100-foot intervals, as well as at bends, HCA start and end points, mainline valves, and other key features.
This approach ensured accurate alignment mapping and compliance with NACE SP0502-2025 standards, which defines the four-step External Corrosion Direct Assessment (ECDA) methodology:
- Pre-Assessment
- Indirect Inspection
- Direct Examination
- Post-Assessment
LaBella also coordinated with local and state agencies to obtain excavation and inspection approvals, ensuring compliance with environmental and right-of-way regulations.
Phase II: Indirect Inspections and Corrosion Assessment
LaBella utilized multiple indirect inspection techniques to identify and characterize potential corrosion threats prior to excavation.
An Alternating Current, Current Attenuation (ACCA) survey was used to measure the electromagnetic field and determine the depth of cover—the distance between the top of the pipeline and the ground surface. By identifying where the AC signal was diminished, or attenuated, the technician was able to detect areas where the protective coating was at risk of corrosion. Current loss and attenuation readings (decibel millivolts) are key indicators of coating degradation.
Alternating Current Voltage Gradient (ACVG) surveys were conducted at 5- to 10-foot intervals, with readings recorded only where anomalies were detected. All anomalies were tagged with sub-meter GPS coordinates.
Direct Current Voltage Gradient (DCVG) surveys were then performed to validate the ACVG results and identify any additional anomalies throughout the HCAs. Indications were logged using a field data collector. A Close Interval Survey (CIS) was also completed to evaluate cathodic protection performance in both ascending and descending directions during an “ON” state. All field observations, including voltage gradient indications, line markers, test stations, and areas of concern, were documented during CIS activities.
All inspection methods were conducted in accordance with NACE SP0109-2023 and SP0502 standards, ensuring data accuracy and technical rigor.
Phase III: Direct Examination and Remediation Oversight
Based on indirect inspection results, LaBella conducted targeted excavations to evaluate corrosion severity and coating condition. At each excavation site, the team performed:
- Visual inspections and photographic documentation
- Wall thickness measurements using Ultrasonic Testing (UT)
- Soil resistivity testing in accordance with ASTM G57 standards
- Deposit analysis to identify corrosive agents
- Documentation of repair methods and materials
- Quality assurance checks on all remediation activities
LaBella also provided construction oversight to ensure coating repairs, backfill, and site restoration met the utility’s construction standards and NACE SP0169 cathodic protection criteria.
The project concluded with the preparation of a comprehensive ECDA report, including GIS-compatible alignment updates, anomaly logs with severity rankings, repair documentation and quality assurance verification, and recommendations for future monitoring and mitigation.
