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Due to congestion and the difficulty in obtaining dedicated right of ways for pipelines, more and more pipelines are being installed in existing High Voltage AC (HVAC) powerline corridors, which may result in AC interference on the pipelines and DC interference on the powerline tower foundations or grounding structures from pipeline cathodic protection systems.
 
AC interference on the pipeline due to inductive, capacitive and resistive coupling between the powerline and the pipeline produces the following risks:

  • Shock to personnel under normal (steady state) operation
  • Shock to personnel under fault conditions
  • Electrical arcing under fault conditions causing puncture or damage to pipeline
  • AC-enhanced corrosion under steady state operation
  • Damage to the coating due to electrical stress under fault conditions
Correng Consulting Service, is one of the industry leaders in performing AC Interference and Mitigation Studies, with over 20 years of experience.

Our typical AC study would utilize computer modeling to predict and mitigate the AC voltages on new or existing pipelines under both steady-state and fault conditions and include the following:
 

  • Collection and/or review of required pipeline and powerline data
  • Site visit to measure soil resistivities and AC voltages, visually confirm powerline parameters and pipeline/powerline configuration, determine ideal locations for mitigation, etc.
  • Computer modeling to predict AC voltages under steady state and fault conditions
  • Assessment of the risk of AC-enhanced corrosion
  • Special calculations for complex scenarios (as required)
  • Conceptual design of mitigation system to address all of the safety and pipeline integrity concerns under both steady state and fault conditions
  • Final Report summarizing the study, including relevant powerline and pipeline parameters, results of the modeling, an AC mitigation table, conclusions and recommendations.

The chart below shows the modeled unmitigated and mitigated steady state AC voltages from one of our projects.
 
 
 
    AC Interference:
Field survey, modeling, mitigation, etc… 		    Corrosion Studies & Investigations:
Material studies, soil corrosivity studies, failure analysis, etc…
 
    DC Interference:
Foreign CP systems, Light rail transit systems, HVDC, Tellurics, etc...		     Pipeline Integrity (ECDA)
 
    Cathodic Protection:
Pipelines, storage tanks, plants and refineries, reinforced concrete, marine, etc…		     Addtional Services:
Grounding System Design, Education, Expert Testimony, Anodic Protection, Research, etc…
 
               
     
 
 
     
 
 
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