A/C Mitigation


AC Mitigation Design and Implementation

Allied Corrosion is able to leverage expertise, skill and experience to your AC Mitigation System Design and Implementation. Our comprehensive engineering services will keep your pipeline assets protected from the serious damaging threats from nearby and paralleling HVAC power structures.

When buried pipelines and overhead HVAC transmission systems share the same right of way, there is a potential risk of AC interference, causing significant damage to and/or failure of the pipeline. Allied Corrosion has the expertise to identify if there are any AC interference risks to include the correct mitigation solution, which nullifies the dangerous and damaging risks. Allied Corrosion's mitigation solution will always has the primary goals of ensuring the highest level of personnel safety, while maintaining the highest degree of pipeline integrity.

Quick Facts

  • AC Interference is not only a threat to the integrity of the pipeline, but is also a significant safety hazard to personnel working on or near a pipeline in a HVAC corridor.
  • AC Mitigation solutions need to take into consideration the cathodic protection system on the pipeline that are in the area of the HVAC power lines. The reason for this is to ensure that neither the mitigation system or the cathodic protection system adversely affects each, but rather compliments each other.

Key Benefits:

Risk Mitigation & Analysis

Analyze potential HVAC interference that can cause significant damage to pipelines, personnel, and other assets.


AC Mitigation is a key part of any compliant pipeline management

Multi-use shared corridors containing high voltage transmission lines and underground pipelines.

AC Mitigation Data, Surveys and Modeling

AC Mitigation Field Data

In order to properly design an AC Mitigation System to protect your assets, a complete range of field data must be taken into account. Allied Corrosion has the expertise and state-of-art instrumentation to conduct the full range of field surveys that are required to model the correct mitigation system for all HVAC interference scenarios.

Data requirements for AC Mitigation include the collection of physical geometry data of the HVAC power structures, tower configurations, phase conductor orientation and geometry, conductor heights at the towers and midpoint between towers, fault data along the HVAC corridor, substation locations, crossing foreign pipelines and other HVAC crossings, and many other parameters that are required to make a successful model for the mitigation system. Field data on pipeline characteristics is also gathered, such as depth of cover, main line valve locations, compressor stations, cathodic protection systems, cased pipeline crossings, pipeline directional bores, CP test station locations, foreign pipeline crossings, and many other data items. All of this data is tied to their GPS location, so that the AC mitigation model can be properly designed.

Soil Resistivity and pH Surveys

Soil resistivity and soil pH (acidity) data is collected and recorded at set intervals and depths along the HVAC corridor and pipeline route. The instruments required for collection of the soil resistivities are special and highly accurate (expensive). Allied Corrosion maintains several sets of these instruments, which are maintained in constant calibration. The soil resistivity measurements are instrumental and integral to successful HVAC mitigation computer modeling. Again these soil resistivity test locations are coupled to their GPS location for accurate computer modeling. This data is essential during for accurate fault modeling and GPR (gradient potential rise) in the soil in and around the pipeline in an HVAC corridor.

Pipeline AC Interference Modeling

With all of the collected data mentioned above that relates to the pipeline(s) and the HVAC power line(s), Allied Corrosion is able to create a computer model of the electrical circuit that defines the two structures in close proximity to each other. Then through multiple combinations of fault conditions, and mitigation solutions, Allied Corrosion can then select the proper mitigation solution which handles all issues dealing with personnel safety and pipeline integrity.

AC Mitigation Solutions

Multi-use shared corridors containing high voltage transmission lines and underground pipelines.

Induced AC Mitigation Systems Design and Implementation

After the AC Mitigation System Design has been selected and finalized, Allied Corrosion can then begin to either install the AC mitigation system, or supervise its installation, to include testing and monitoring. From design and development, to materials selection, installation, and ultimately the training of pipeline operation personnel on the maintenance and operation of the AC mitigation system, Allied is ready to prepare your AC Mitigation System project to protect your asset for the duration of its life.

The Allied Corrosion Difference

We have assisted many pipeline owner/operators with their AC mitigation problems by finding low cost and long-life solutions. Typically, induced AC scenarios fall into two major categories. First is the “Step Potential” category. This exists when there is induced AC present on a pipeline appurtenance that can be touched by someone. When the induced AC exceeds 15 VAC, which is the safe “hand let-go” threshold for a normal size male, there is the danger of personal injury and/or death, and the problem should be mitigated. The second category is associated with pipeline segments where AC current is discharged from the pipe’s metal surface to the ground.

The two most common types of AC current discharge are steady state and fault current discharge. AC corrosion/metal loss will begin to occur whenever the threshold current density of 20 A/M2 is exceeded. The severity of metal loss for either type of discharge is directly related to the AC current density in the discharge area, and the discharge length of time. In some cases, actual pipe wall penetration/failure can result from just one massive ground fault event. We have been very successful in providing a variety of reasonable, well-engineered AC Mitigation Systems for the pipeline industry.

With 40 years of industry experience, Allied Corrosion is able to leverage expertise and skill to your AC Mitigation System Design and Implementation. Our comprehensive engineering services will keep your pipeline assets protected for the duration of its life. We approach every project as if we are the owners, with the specific goals of never sacrificing personnel safety and achieving complete pipeline integrity!

Person working on mapping blueprints at a desk.

Contact Allied Corrosion Today


1550 Cobb Industrial Dr.  |  P.O. Box 9098  |  Marietta, GA 30065-2098

770-425-1355 (Phone) | 770-425-1354 (Fax) | (Email)

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Voltage Range
Relative Position
Least Noble (More Anodic)
-1.60V to -1.67V
-1.00V to -1.07V
-0.93V to -0.98V
Aluminum Alloys
-0.76V to -0.99V
-0.66V to -0.71V
Mild Steel
-0.58V to -0.71V
Cast Iron
-0.58V to -0.71
Low Alloy Steel
-0.56V to -0.64V
Austenitic Cast Iron
-0.41V to -0.54V
Aluminum Bronze
-0.31V to -0.42V
Brass (Naval, Yellow, Red)
-0.31V to -0.40V
-0.31V to -0.34V
-0.31V to -0.40V
50/50 Lead/Time Solder
-0.29V to -0.37V
Admiralty Brass
-0.24V to -0.37V
Aluminum Brass
-0.24V to -0.37V
Manganese Bronze
-0.24V to -0.34V
Silicon Bronze
-0.24V to -0.30V
Stainless Steel (410, 416)
-0.24V to -0.37V
(-0.45V to -0.57V)
Nickel Silver
-0.24V to -0.30V
90/10 Copper/Nickel
-0.19V to -0.27V
80/20 Copper/Nickel
-0.19V to -0.24V
Stainless Steel (430)
-0.20V to -0.30V
(-0.45V to -0.57V)
-0.17V to -0.27V
70/30 Copper Nickel
-0.14V to -0.25V
Nickel Aluminum Bronze
-0.12V to -0.25V
Nickel Chromium Alloy 600
-0.09V to -0.15V
(-0.35V to -0.48V)
Nickel 200
-0.09V to -0.20V
-0.09V to -0.15V
Stainless Steel (302, 304, 321, 347)
-0.05V to -0.13V
(-0.45V to -0.57V)
Nickel Copper Alloys (400, K500)
-0.02V to -0.13V
Stainless Steel (316, 317)
0.00V to -0.10V
(-0.35V to -0.45V)
Alloy 20 Stainless Steel
0.04V to -0.12V
Nickel Iron Chromium Alloy 825
0.04V to -0.10V
0.04V to -0.12V
0.20V to 0.07V
0.20V to 0.07V
0.36V to 0.19V
Most Noble (More Cathodic)

Primary voltage range for material
Voltage range in crevices or stagnant and poorly aerated water