Mears Hosts Workshop On ECDA For Cased Pipelines

By Oliver Klinger, Publisher | January 2010 Vol. 65 No. 1

The research facility also offers hands-on training for pipe excavation, pipe-coating removal, surface preparation, coating application, evaluating casing isolation, DA indirect inspection surveys and pipe-direct examinations. It allows the detection of coating flaws with DA survey techniques and/or available equipment. The impact of different coatings and cathodic protection configuration can be analyzed with the detection capabilities of the equipment. Real-world surfaces such as soil, gravel, asphalt and concrete are installed to demonstrate their impact on survey techniques.

Wax filling
Using a clear casing pipe, a demonstration on the wax-filling process was conducted by Royston (Chase Corporation). Some considerations before doing a wax filling are:

  • Repeat indirect inspections;
  • Excavate both ends and remove a portion of the casing to examine the ends of the cased pipe;
  • Clear all electrolyte with high-volume flushing;
  • Clear metallic shorted conditions;
  • Repeat indirect inspections;
  • Use the guided wave test as part of PHMSA 18-point process;
  • Vent the low side at the 6 o’clock position and the high side at the 12 o’clock position;
  • Install good quality end seals;
  • Backfill and compact;
  • Blow air from high to low side;
  • Air test up to 5 psi;
  • Calculate fill volume (actual fill cannot vary from this by more than 15% or you must explain why);
  • Fill casing low side to high side; and
  • Repeat indirect inspections.

Testing and field results by Mears have validated the applicability of ECDA to cased pipelines. Indirect tests find metallic and electrolytic conditions. Process elements and guided wave assess for atmospheric corrosion. The process improves safety by identifying when potentially corrosive situations exist, mitigating those conditions, allowing examination of the pipeline and eliminating the EC threat with wax filling.

Baltimore Gas & Electric program
BG&E has over 650,000 customers and a large part of its system is in high consequence areas, including 70 casings. They started a casing pilot program in 2007 in which they tested five casings with the guided-wave method and later removed to qualify the results. They wanted to prove out new ECDA-casing test procedures as well as gather statistical and economic data on GWUT and casing removal. BG&E also wanted to assess the economic impact and overall direction in remediating casings.