Assessing the coating condition of buried pipelines

Assessing the coating condition and possible corrosion risk of buried pipework is a familiar problem within the petrochemcial industry. A survey technique originally developed to monitor coating conditions and locate defects on cross-country pipelines has recently been modified to suit plant situations. The procedure employs C-SCAN, a computerized system manufactured by Dynalog Electronics of Bristol, to monitor the variations in magnetic flux produced by changes in coating condition. The technique has proved successful in detecting cracking due to aging of coating materials, tears due to machine damage during pipe laying, indentations due to settlement of pipeline or use of unsuitable backfill materials, and coating disbondment due to poor surface preparation or poor control of applied cathodic protection.