1. Q: Why is carbon steel pipe ASTM A120 largely obsolete?
A: It was a general-purpose standard superseded by more specific ones like A53. Its requirements were less stringent, especially for material traceability and testing.
2. Q: What is galvanic corrosion and how does it affect carbon steel pipe coupled with brass valves?
A: Carbon steel (anodic) will corrode preferentially when electrically connected to brass (cathodic) in an electrolyte (e.g., water). Insulating gaskets or unions are required.
3. Q: What is the purpose of hydrostatic testing per ASTM/ASME standards?
A: To verify structural integrity and leak tightness by pressurizing the pipe to a level above its design pressure (typically 1.5x) for a specified time.
4. Q: What does "NPS" stand for and how does it relate to the actual pipe diameter?
A: Nominal Pipe Size. For NPS 1/8" to 12", the number approximates the inside diameter. For NPS 14" and above, it equals the outside diameter in inches.
5. Q: What is the common corrosion allowance for carbon steel pipe in mild process service?
A: Typically 1/16 inch (1.6 mm) or 3 mm, but it depends entirely on the corrosivity of the fluid and design life.
