1. Q: What is the difference between "Pipe" and "Tube"?
A: Pipe is designated by Nominal Pipe Size (NPS) for conveying fluids, emphasizing pressure rating. Tube is designated by outside diameter or wall thickness, used for structural purposes, and has tighter tolerances.
2. Q: How is the wall thickness of pipe measured?
A: Typically specified as "wall thickness" in inches or mm. For tubes, it's often specified by a gauge number (like BWG - Birmingham Wire Gauge).
3. Q: What is a "lap weld" pipe?
A: An older, obsolete method where the skelp (strip) was overlapped at the seam and forge-welded. It's weaker than modern butt-welded methods.
4. Q: What does "continuous weld" (CW) pipe mean?
A: Similar to furnace butt-weld, made by forming hot-rolled strip and butt-welding in a continuous furnace. Used for low-pressure plumbing.
5. Q: What is a "casing" pipe?
A: A large-diameter pipe used as a structural retainer for walls, or as a conduit/protection for underground utilities (like for oil wells or as a bore casing).
