关于埋地防腐层管道直流电位梯度(DCVG)测量与%IR计算的讨论

Discussion on DC Voltage Gradient(DCVG)Measurement and%IR Calculation of Buried Coating Pipeline

直流电位梯度法(DCVG)是一种用于防腐层缺陷评估的间接测量方法。DCVG检测的实施对直流测试电流以及中断器的设置都有一定的要求,但这些技术细节在现场实际工作中往往被忽略。%IR是DCVG方法中用于评价防腐层破损严重程度的参数,对于该参数的计算和应用,在管道业界存在诸多误区,比如测试电流的大小和通断周期的选取有误、在评价时未考虑土壤电阻率和埋深等影响因素等。本文针对DCVG的测试电流要求以及%IR的原理和计算方法进行了研究和讨论,明确了开展DCVG测试的信号强度要求,分析了对%IR值存在影响的因素,指出了利用%IR评价破损点大小和严重程度仍具有不确定性。

The direct current voltage gradient method(DCVG)is an indirect measurement method used to evaluate defects in anti-corrosion coatings of pipeline.The implementation of DCVG detection has certain requirements for the DC test current and the setting of interrupters,but these technical details are often ignored in actual on-site work.%IR is a parameter used in the DCVG method to evaluate the severity of pipeline coating damage.There are many misconceptions in the calculation and application of this parameter in the pipeline industry,such as the incorrect selection of the test current and on-off period,and lack of consideration of factors such as soil resistivity and burial depth of the pipe.This article has conducted research and discussion on the testing current requirements of DCVG and the principle and calculation method of%IR,clarified the signal strength requirements for conducting DCVG inspection,analyzed the factors that affect the%IR value,and pointed out that its uncertain to evaluate the size and severity of coating defects using%IR.