Intergranular Corrosion: IGC: Piping Quiz

FAQs on Intergranular Corrosion (IGC)

• What is Intergranular Corrosion (IGC)? Intergranular corrosion is a form of corrosion that occurs preferentially along grain boundaries of a material, typically due to sensitization or other metallurgical changes.

• What causes Intergranular Corrosion in piping systems? IGC is commonly caused by sensitization of stainless steels, where chromium carbides precipitate along grain boundaries, depleting chromium in the surrounding areas and making them susceptible to corrosion.

• How can sensitization lead to Intergranular Corrosion? Sensitization occurs when stainless steel is heated in a temperature range (around 450-850°C), causing chromium carbides to precipitate at grain boundaries, reducing the alloy’s corrosion resistance.

• Which materials are most susceptible to Intergranular Corrosion? Austenitic stainless steels such as 304, 316, and their variants are particularly susceptible to IGC if not properly heat-treated or if exposed to sensitizing temperatures during welding or processing.

• How can Intergranular Corrosion be detected in piping systems? IGC can be detected through visual inspection, dye penetrant testing, or by conducting corrosion tests like the ASTM A262 Practice A test for detecting susceptibility to intergranular attack.

• What are the consequences of Intergranular Corrosion in piping? It can lead to premature failure of piping systems, especially in critical applications where corrosion resistance is essential for structural integrity and safety.

• How can Intergranular Corrosion be prevented in piping systems? Prevention methods include using low-carbon variants of stainless steel, applying post-weld heat treatment, choosing appropriate welding procedures, and avoiding sensitizing temperatures during fabrication.

• What are the standards or guidelines related to Intergranular Corrosion testing? ASTM A262 is a widely recognized standard for detecting susceptibility to intergranular attack in austenitic stainless steels.

• Can Intergranular Corrosion occur in non-stainless steels? Yes, although less common, it can occur in other alloys where grain boundary precipitation of detrimental phases reduces corrosion resistance.

• Is Intergranular Corrosion reversible once it starts in piping systems? Once intergranular corrosion initiates, it typically progresses and is not reversible without corrective measures such as repair or replacement of affected components.