Q: What is "Black Steel" pipe?
A: Pipe that has a dark iron oxide scale on its surface from the manufacturing process (mill scale). It is not corrosion-resistant like galvanized pipe.
Q: What is "Schedule" in pipe sizing (e.g., Schedule 40, 80)?
A: It defines the wall thickness for a given nominal pipe size (NPS). Higher schedule number means thicker walls and higher pressure rating.
Q: What is the difference between "NPS" and "DN"?
A: Nominal Pipe Size (NPS) is the North American standard, indicated in inches (e.g., NPS 4). Diameter Nominal (DN) is the metric equivalent, in millimeters (e.g., DN 100).
Q: What is "HIC Test" (Hydrogen Induced Cracking)?
A: A test for pipes used in sour service (containing H2S). It evaluates the steel's resistance to cracking caused by hydrogen atoms penetrating the metal.
Category 3: Manufacturing and Processing
Q: What is the "Normalizing" heat treatment?
A: A process of heating the steel to above its critical temperature and then air-cooling. It refines the grain structure, improves mechanical properties, and relieves stresses.
