Dry gas (DG) internal corrosion direct assessment (ICDA) methodology was applied to a dry gas pipeline segment in Southern China. This line was constructed in 2003 and put in operation in 2004. Internal corrosion (IC) was suspected due to suspected possible water intrusion into the line during upsets and due to water condensation. ICDA was used for the pipe segment because both the gas flow and pressure were low, which made the line unpiggable. The four-step process described in the NACE Dry Gas ICDA Standard Practice (SP0206-2006) was attempted to be implemented while in the end the detailed examination step was executed only with guided wave ultrasonic testing (GWUT) and the GWUT was performed in only two selected points. Despite the above incompliance with NACE SP0206, a more accurate determination of the critical angle and pipeline inclination angles was performed. One other location was also selected and GWUT performed because of suspected IC by water condensation. For all three locations, GWUT found no obvious IC. The reassessment interval was determined to be seven years.

Subject
Test methods, Water, Piping, Corrosion rate, Condensation, Pipelines, Gas pressure, Liquids, Liquid water, Internal corrosion, Pipe sections, Corrosion data, Internal corrosion direct assessment
Keywords:
pipeline, dry gas, internal corrosion, direct assessment, standard
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2011
Association for Materials Protection and Performance (AMPP)
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