Methodology for Surveying Buried Plant Piping for Coating Condition and CP Effectiveness

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.