1. Q: What is "Normalized" heat treatment?
A: A process where the pipe is heated above its critical temperature and air-cooled to refine the grain structure, improve mechanical properties (toughness, uniformity), and relieve stresses.
2. Q: When is Quenched & Tempered (Q&T) heat treatment required?
A: Primarily for high-strength, low-alloy (HSLA) grades like API 5L X70 and above, to achieve superior strength and toughness for demanding oil & gas transmission lines.
3. Q: What is the typical size range for seamless pipes?
A: Standard outside diameters range from 1/8" (10.3mm) to 24" (610mm) and larger. Wall thickness is defined by schedule (e.g., SCH40, SCH80, SCH160) or a specific value.
4. Q: What is the difference between "Schedule" and "Wall Thickness"?
A: Schedule (SCH) is a standardized number system (40, 80, 160, etc.) defining approximate wall thickness for a given NPS (Nominal Pipe Size). "Wall thickness" is the specific measured value in mm or inches.
5. Q: What testing is performed on seamless pipes?
A: Standard tests include Hydrostatic Pressure Test, Non-Destructive Electric Test (NDT) like Eddy Current or Ultrasonic, Mechanical Tests (Tensile, Hardness), and Chemical Analysis.
