| 1. A newly hydrotested ASTM A312 TP 316L system developed leaks at welds within months. What's a likely cause? | Microbiologically Influenced Corrosion (MIC) caused by stagnant, untreated hydrotest water left inside the pipes, especially in the heat-tinted zones around welds-6. |
| 2. Why are weld and HAZ areas on stainless pipes sometimes more prone to pitting corrosion? | Welding can create heat-tinted zones (oxidation) and alter the microstructure, reducing local corrosion resistance. The HAZ can also experience sensitization in certain grades-6. |
| 3. How can intergranular corrosion in stainless steel weldments be prevented? | By using low-carbon grades (e.g., 316L instead of 316) or grades stabilized with Ti or Nb (e.g., 321, 347), and following proper welding procedures to minimize time in the sensitization temperature range. |
| 4. What standard is common for welded austenitic stainless steel boiler, heat exchanger, and condenser tubes? | ASTM A249/A249M is a standard specification for welded austenitic steel boiler, superheater, heat-exchanger, and condenser tubes-10. |
| 5. What does the "L" suffix denote in a grade like 316L? | It denotes a Low carbon content (typically ≤0.03%), which enhances resistance to sensitization and intergranular corrosion during welding-6. |
