Below Grade Service (Pipelines and Tanks)

Hi all,

I am having trouble finding any documentation pertaining to performing High Voltage Holiday Testing on underground piping that has a Cathodic Protection 

system installed. Stopaq is being applied to the piping and 15kV is being used. Will it damage the the CP system?

Cheers!

James,

The holiday detection won't harm the CP system.  Even though the voltage is high, the amperage being pushed into the pipe by the holiday detector is low.  Also, the small current being put onto the pipe with the holiday detector is jumping off the pipe somewhere else to come back to the earth through your ground (or if you're grounded to the pipe, right back through the pipe to the detector).  The current isn't being sent back up the CP system to the rectifier.

Many, many decades of holiday detection on pipes with impressed current CP systems running with no problems is the proof.  For documentation, maybe the holiday detector manufacturer has some literature about the amperage.

Per Allied Construction's page on the Tinker/Rasor M1 holiday detector:

"The detector operates from 110/120 volt 50/60 cycle A.C. line current. The electrical design of the M1/AC Holiday Detector utilizes a sensitive relay which is activated by a voltage regulated, solid state power supply. When a current of approximately 750 micro-amperes flows through the system the relay closes and actuates the signal bell."*

*https://www.alliedcorrosion.com/product/holiday-detector-model-m1-ac/ 

Hi all,

I am having trouble finding any documentation pertaining to performing High Voltage Holiday Testing on underground piping that has a Cathodic Protection 

system installed. Stopaq is being applied to the piping and 15kV is being used. Will it damage the the CP system?

Cheers!