Close interval survey: a walking survey in which a technician trails a wire connected at a test station and records pipe-to-soil potentials at short spacing, typically every 1 to 1.5 m, using a reference electrode on a probe pole. With interrupters cycling the rectifiers it produces on and instant-off profiles that reveal under-protected stretches, interference and coating damage between test stations. Results are plotted against distance and GPS position.
CIS shows a 200 metre dip below -850 off right where the line crosses the creek.
Also heard as
- close interval survey
- CIPS
- over-the-line survey
Related terms
Interrupter
Timed switch fitted to a rectifier or bond that cycles CP current on and off for instant-off readings.
Ons and offs
Survey slang for paired on and instant-off potential readings taken while rectifiers are being interrupted.
DCVG
Direct current voltage gradient survey that locates and sizes coating holidays on buried pipe.
Pipe-to-soil potential
Voltage between a buried pipe and a reference electrode on the soil surface, the basic CP measurement.