1. Q: For a sour service application requiring seamless pipe, what grade might be specified under API 5L?
A: API 5L X52 S or similar, where "S" denotes suitability for sour service, with restricted chemistry (e.g., max hardness 22 HRC, CE limits) and often HIC tested.
2. Q: What is the purpose of "Galvanizing" on carbon steel pipe, and is it common for seamless?
A: To apply a zinc coating for corrosion protection in atmospheric or mild service. Seamless pipe (A53) can be galvanized, but the high-temperature process can affect mechanical properties; A106 is typically not galvanized.
3. Q: What is "Drill Pipe" in the oil industry, and is it seamless?
A: Yes, it is a high-strength, seamless, alloy steel pipe (typically to API 5D) used to rotate the drill bit and circulate drilling fluid in oil/gas wells.
4. Q: What does the marking "ASTM A106 Gr. B +N" indicate?
A: The "+N" indicates the pipe was supplied in the normalized heat-treated condition, providing enhanced properties.
5. Q: What is a major cause of failure in carbon steel steam pipes?
A: Flow-Accelerated Corrosion (FAC) or erosion-corrosion, where protective magnetite layer is dissolved by flowing water/steam, leading to wall thinning. Chemistry (low Cr) and flow velocity are key factors.
