1. Q: What does "Dimensional Tolerance" refer to?
A: It defines the allowable deviation from specified pipe dimensions, such as Outer Diameter (OD), Wall Thickness (WT), and length. Standards like ASTM and API define these tolerances (e.g., ±1% for OD in ASTM A106).
2. Q: What is "Wall Eccentricity" and why is it important?
A: It refers to the variation in wall thickness around the pipe's circumference. Excessive eccentricity creates a weak point and can cause failure under pressure. Seamless pipes generally have better concentricity than welded pipes.
3. Q: Name common Non-Destructive Testing (NDT) methods for seamless pipes.
A: Ultrasonic Testing (UT): For detecting internal/sub-surface flaws. Eddy Current Testing (ECT): For surface/near-surface defects. Hydrostatic Test: For verifying pressure integrity. Magnetic Particle Inspection (MPI): For surface defects on ferromagnetic steels.
4. Q: What is tested in a "Hydrostatic Test"?
A: The pipe is filled with water, pressurized to a specified test pressure (calculated from the grade's yield strength and dimensions), and held to check for leaks or permanent deformation, ensuring integrity under pressure.
5. Q: What is "Charpy V-Notch Impact Test"?
A: It measures the absorbed energy (in Joules or ft-lbs) by a notched sample when struck by a pendulum hammer at a specified temperature. It quantifies the material's toughness and resistance to brittle fracture.
