Premature failure of superduplex stainless steel pipe by pitting in sea water environment

• Superduplex tube failed by pitting corrosion in service with seawater at room temperature.
• The critical pitting temperature was decreased to 32 °C due to σ phase precipitation.
• The tube was over-heated to correct distortion before a repair welding.
• The σ precipitation was so intense that could be detected by hardness and ferritoscope measurements.