Large supply of DCVG DC voltage gradient detector

Large supply of DCVG DC voltage gradient detectorTechnical Introduction

When cathodic protection current (CP) is applied to the pipeline, a ground electric field distribution is established on the ground above the pipeline due to the voltage gradient formed by the damage point of the pipeline anti-corrosion layer and the soil. The closer to the damaged point, the greater the voltage gradient and the higher the current density on the ground above the pipeline. Generally speaking, the larger the exposed area, the higher the current density near it, and the greater the voltage gradient on the ground.

DCVG measurement method

It is to connect an interrupt device in series with the cathodic protection device of the protection station, so that the CP current can be turned on/off at a certain time period. The on/off time is corrected by GPS synchronization technology to ensure synchronization with the receiver. During the inspection, the location of the defect is determined by measuring the potential gradient on the ground and the direction of the current in the soil above the pipeline. The receiver also comes with a GPS synchronization system. During measurement, one electrode probe is placed directly above the pipeline, and the other probe is placed at one point in the pipeline. The two probes are separated by about 1 meter, and a set of data is measured every 1 meter along the direction of the pipeline. Based on the measurement results, the defect location and level can be accurately located.

Large supply of DCVG DC voltage gradient detector

Detection characteristics of DCVG

DCVG provides complete information in the quantitative detection of anti-corrosion coatings, and when combined with CIPS detection technology, it can comprehensively detect and evaluate the corrosion and protection of buried pipelines in terms of the effectiveness of cathodic protection systems

Localization of defects in the anti-corrosion coating and assessment of the severity of damage

Measure the degree of protection of the pipeline at the location of the anti-corrosion coating defect

Identify the corrosion activity of defects based on the changes in cathodic protection current reflected by the ground electric field

Identify and locate the interference of underground facilities on the detection of cathodic protection systems

■ Determine the location of the inflow and outflow points of DC stray current at the point of pipeline anti-corrosion coating damage

■ Locate the anode ground bed and evaluate the impact range of the anode field effect

By analyzing the attenuation trend of DCVG signal amplitude, it is possible to identify the corrosion status of larger anti-corrosion coating damage areas

Determine whether to adjust the cathodic protection current by detecting the current direction of defects in the anti-corrosion layer to ensure that all defects are adequately protected

The main advantages of analog DCVG

High positioning accuracy (within 10 centimeters) for damaged anti-corrosion coating of pipelines

■ The detection indicator is intuitive and easy to operate

During the DCVG detection process, conduct a detailed inspection of the accessible pipeline areas

■ Able to determine the presence of DC stray current interference and the current inflow/outflow points at the damaged area

■ Can determine whether the damaged location of the anti-corrosion layer has received cathodic protection

■ Determine the location of the damage to the anti-corrosion coating of the large pipeline in the circumferential direction of the pipeline;

Before excavation, the approximate shape of the damaged anti-corrosion layer can be determined

The DCVG technology of * * can detect complex pipeline networks and pipelines under high voltage lines

To determine whether to adjust the settings of the rectifier so that the damaged anti-corrosion layer receives sufficient cathodic protection current

Standard configuration of DCVG equipment