Failure analysis of firewater pipeline

• Stagnancy of water inside the pipe.
• Excess of dissolved oxygen in the water causes the hydroxide(s) to oxidize further to produce final corrosion product, iron oxide.
• Due to gravity affect, the corrosion product produced by the oxygen attack fell down to the bottom surface of the pipe.
• The severe pitting attack at the top inner portion of the pipe was due to high oxygen corrosion while the bottom surface of the pipe suffered from under deposit corrosion problem.

This paper presents the failure analysis of a fire water pipe line from a petrochemical industry. Leakages were noticed at the top portion of the pipeline. Severe deep pits were observed at the top inner surface and deposits found at the bottom inner surface of the pipe line. Visual inspection, microscopic examination, chemical and water analyses were employed in the present failure analysis. The analysis results showed that the failure occurred due to the severe oxygen corrosion attack at the top portion of the pipe while the bottom surface of the pipe suffered from under deposit corrosion. The fire water pipe line was made of low carbon steel.