In November 2011, a Root Cause Analysis (RCA) was conducted in order to determine the source of multiple leaks in a 6 in pipeline that supplies nitrogen to a glass plant in the municipality of Los Garza, NL in Mexico. Leaks were detected after the rehabilitation of damaged sections of the pipeline as a consequence of Hurricane Alex, which affected the city of Monterrey in July 2010. Following the re-commissioning of the pipeline, a loss of pressure occurred due to multiple leaks in the last section of the pipeline.

After a complete assessment that involved soil conditions, damaged pipeline examination and inspection of corrosion control systems, it was possible to identify all the factors involved in the corrosion processes that led to the loss of wall thickness in the nitrogen line.

The evaluation of corrosion control systems was conducted under the scheme of the External Corrosion Direct Assessment methodology (ECDA). Both, cathodic protection systems and the pipeline coating were evaluated by indirect measurements and direct inspections. The cathodic protection coverage in the surveyed area was poor, while the evaluation of the coating revealed severe damage.

Subject
Coating inspection, Water, Cathodic protection, Glass, Tape, Leaks, Pipelines, Soil resistivity, Acidity, Nitrogen, External corrosion, Corrosion protection, Soil
Keywords:
Root Cause Analysis, Direct Assessment, Cathodic protection shielding
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2013
Association for Materials Protection and Performance (AMPP)
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