Evaluating the pipeline coating with direct and alternating current voltage gradient survey (DCVG/ACVG)
Direct current voltage gradient (DCVG) and alternating current voltage gradient (ACVG) surveys are methods used to evaluate the coating condition of buried pipelines and locate and analyze coating “holidays” or defects.
Direct Current Voltage Gradient Survey
In a DCVG, a direct current (DC) signal is applied to the pipeline and the voltage gradient in the soil above the pipeline is measured. Voltage gradients, as measured between two calibrated reference electrodes spaced apart, arise as a result of the current pickup or discharge at pipeline coating holiday locations.
Alternating Current Voltage Gradient Survey
Similar to a DCVG survey, alternating current voltage gradient (ACVG) surveys utilize an alternating current signal applied to the pipeline to create the voltage gradient at the location of a coating holiday.
Both ACVG and DCVG surveys are known to be more precise in the detection of coating holidays over other methods such as the use of a Pipeline Current Mapper. The DCVG survey is the only method available that can aid in approximating the size of pipeline coating holidays.
Qualified MATCOR technical personnel can conduct DCVG and ACVG surveys in the field oil, gas and water pipelines. Data is then analyzed by NACE certified experts.
With MATCOR, you benefit from:
- Over 40 years of experience with all types of cathodic protection systems
- Experience testing, installing and maintaining cathodic protection systems for all types of structures throughout the world
- Highly qualified professional and NACE corrosion engineers and technicians
- Team members with experience on the client side of CP projects
- Experience managing multi-million dollar CP projects and corrosion departments of large utilities and pipeline companies
- MATCOR’s many proprietary cathodic protection systems that are lower in cost and have longer lives than some commonly used CP systems
MATCOR’s mission is to solve your corrosion problems. We are ready to assist with your corrosion engineering and field service needs, including design, manufacturing, installation, commissioning and ongoing maintenance, as well as project management and full turnkey solutions. In addition, we offer a broad range of proprietary corrosion prevention products.
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