PC&S offers a full catalog of turnkey Corrosion Control Solutions. Our dedicated workforce is comprised of AMPP-certified technicians, registered engineers, and experienced project managers. Although we operate nationally, we take pride in working closely with our customers to design, engineer, and implement corrosion control and AC/DC mitigation systems.
Services Include:
- Technical Services (Over the Ground Survey, Survey Mitigation, DC Interference Testing and Assessment, AC Mitigation Testing, Data Analysis and Reporting)
- Engineering Design (Cathodic Protection, AC/DC Mitigation, Project Management, Program Management, Data Management)
- Construction (AC Mitigation, CP System Installation, Test Station Installation, Material Selection & Procurement)
- Inspection (Coating Inspection, Construction, Pipeline Remediation Projects, Operations Representatives, Atmospheric Inspection)
- Pipeline Field Services (Inspection, GIS mapping)
CASE STUDY : AC Mitigation Engineering Summary
PC&S undertook the design and implementation of an advanced alternating current (AC) mitigation system for a newly constructed transmission pipeline with a total length of 550 miles, encompassing segments of both 24-inch and 30-inch diameter. Due to the pipeline’s proximity to high-voltage power lines (HVPL), significant AC interference was anticipated along the route. The project addressed several principal safety hazards, including personnel shock risks, hazardous touch and step potentials surpassing the NACE SP0177 15V AC safety threshold, and threats to asset integrity arising from AC-induced corrosion and coating stress failure during high-voltage fault events. The diverse terrain, variable soil resistivity, numerous HVPL crossings, and the complex HVPL alignment necessitated the development of tailored engineering solutions throughout the pipeline corridor.
The AC mitigation analysis performed by PC&S comprised three principal phases:
- A comprehensive corridor assessment utilizing predictive computer modeling to identify induced voltage profiles and critical locations.
- Development of a multi-layered mitigation system design, integrating gradient control wire systems, grounding grid networks, and solid-state decoupling equipment.
- Meticulous integration planning to ensure compatibility with the newly implemented impressed current cathodic protection system and existing assets.
Rather than adopting a uniform mitigation approach throughout the entire pipeline system, PC&S established an adaptive mitigation zoning strategy. This methodology divided the 550-mile pipeline into zones categorized as high risk, moderate risk, and low risk. By optimizing protection for both the pipeline asset and personnel, this strategy enabled effective cost management for the client.
During the construction phase, the following mitigation components were installed:
- Copper gradient control wire installed parallel to the pipeline
- AC decouplers positioned at strategic points
- Deep electrical grounding systems installed at designated locations
- Gradient control mats placed at mainline valve sites and launcher/receiver facilities
- AC coupon test stations deployed to facilitate ongoing monitoring and testing
Subsequent to construction, a series of tests were conducted to validate the effectiveness of the mitigation system. These included:
- Comprehensive AC voltage surveys at one-mile intervals
- Touch potential measurements at all above-ground appurtenances
- Performance testing of the AC mitigation system against the original design criteria
- Copper gradient control wire installed parallel to the pipeline
- AC decouplers at strategic locations
- Deep electrical grounding systems at specified points
- Gradient control mats at mainline valve sites and launcher/receiver facilities
- AC coupon test stations for sustained monitoring and testing
The project attained full compliance with NACE SP0177 AC mitigation standards, with no locations exceeding the 15V AC safety threshold across the entire 550-mile pipeline. AC-induced corrosion risks were comprehensively mitigated, while the impressed current cathodic protection system operates without interference among the multiple pipelines.
This project’s success underscores PC&S’s proficiency in the execution of AC mitigation initiatives. Through comprehensive planning, rigorous engineering, and systematic implementation, critical energy infrastructure was protected, ensuring decades of safe, reliable operation for client personnel, assets, and the surrounding environment.
