The paper describes the theoretical and practical aspects of merging two Indirect inspection tools (i.e. Close Interval Potential Survey and DC Voltage Gradient) into one integrated survey, as used in 2004 during an ECDA project covering more than 21 Km of gas pipelines in Southern Ontario.
A method was developed and verified m the field to calculate the %IR at coating defects using the recorded data, with no need to interrupt the survey or to return to the defect location in order to measure the total gradient to remote earth.
The data processing was Improved by deriving the longitudinal gradient profile from the Close Interval Potential Survey data This enhancement will be used in future surveys to validate indications in conjunction with the measured lateral gradient data.
