Recently, we have supplied a batch of Inconel alloy 600 forged flanges and butt welding pipe fittings to a client from the U.S.. The products include: weld neck flanges 150# 8″, blind flanges 150# 8″ & 12″, elbow L/R 90° SCH40, end caps SCH40 3″. Materials standards: ASTM B564/ B366 UNS N06600; Manufacturing standards: ASME B16.5, ASME B16.9, respectively. All materials were solution treated at temperatures between 1050°C and 1100°C. Considering its corrosive service environment, intergranular corrosion test should be performed in accordance with ASTM G28.

ASTM G28 specifies standard test methods for detecting susceptibility to intergranular corrosion in wrought, nickel-rich, chromium-bearing alloys. According to purchase specification, method A, ferric sulfate – sulfuric acid test was conducted. 6 pieces of Inconel alloy 600 specimens, with the same heat number as the flanges and fittings, were prepared. They were immersed into the test solution for 24 hours. Mass losses were measured and recorded for further calculation of corrosion rates. The corrosion rates finally determined are: 0.46, 0.42, 0.53, 0.35, 0.32, and 0.33 mm per year. The data all fall in the range of acceptance criteria.