Grounded plant piping networks and cross country pipelines are different, and so must be their
respective corrosion survey methods. Pipeline coating condition and cathodic protection (CP) survey
techniques do not provide meaningful data in a plant environment.
This paper presents a unique plant corrosion survey process and discusses how the subsequent
graphical presentation facilitates data interpretation and analysis. A computer based data logger is
used to collect Cu/CuSO4 reference cell potentials measuring areas of the plant, while dual earth
current voltage gradients are collected in a rectangular co-ordinate “normal” X-Y grid. The process is
called an Area Potential and Earth Current (APEC) survey. After processing, the APEC data is
integrated for evaluation into a Geographic Information System (GIS) in relation to the location of all
buried plant assets. The APEC survey presents a massive data set that enables this specialized
indirect inspection survey methodology to provide the information necessary to define significantly
active corrosion cells, determine the plant piping coating condition, and evaluate the performance of all
influencing CP systems from a detailed graphical representation.
The paper introduces the APEC survey methodology, and the slide presentation will provide case
histories demonstrating the effectiveness of APEC in a plant environment.
Keywords: nuclear, power plant buried pipe, cathodic protection, grounded piping, indirect inspection,
pipe-to-soil, earth currents, voltage gradients, CIS, DCVG, plant piping, corrosion surveys, polarization,
geographic information system, methodology, telluric current, monitoring, data loggers, rectangular
coordinates, polar coordinates, area potentials