1. Q: What is the most common specification for seamless carbon steel pipe in high-temperature service?
A: ASTM A106 (Grades A, B, C). Grade B is the most widely used for temperatures up to about 750°F (399°C).
2. Q: What is the key difference between ASTM A53 and ASTM A106 pipe?
A: A53 covers both welded (Type E, ERW) and seamless (Type S) pipe for general use, while A106 is specifically for seamless pipe intended for high-temperature service.
3. Q: Which carbon steel pipe grade is preferred for low-temperature applications and why?
A: ASTM A333 Grade 6. It is a killed fine-grain steel with improved impact toughness at temperatures as low as -50°F (-45°C).
4. Q: What causes graphitization in carbon steel pipes and which grade is most susceptible?
A: Long-term exposure to temperatures above 800°F (427°C) causes carbon to form graphite nodules. ASTM A106 Gr. A/B are susceptible; Gr. C has slightly better resistance.
5. Q: When is ASTM A53 Type F (furnace butt-welded) pipe typically used?
A: For low-pressure, non-critical applications like fencing, handrails, or drainage, where the smooth interior weld is acceptable.
