Q1: What is the difference between Yield Strength and Tensile Strength?
A1: Yield strength is the stress at which a material begins to deform plastically. Tensile strength (or ultimate strength) is the maximum stress it can withstand before fracturing -10.
Q2: What is the purpose of a flattening test on a seamless pipe?
A2: The flattening test is a quality check to assess the ductility of the steel and the soundness of the pipe wall. The pipe is flattened to a specified gap between plates without cracking -3.
Q3: What is a Charpy V-Notch (CVN) impact test?
A3: It is a test that measures the amount of energy a material absorbs during fracture at a specific temperature. It is critical for determining the ductile-to-brittle transition temperature, especially for low-temperature services (ASTM A333) -5-6.
Q4: What is a Hydrostatic test?
A4: It is a pressure test where the pipe is filled with water and pressurized to a specific level to verify the leak tightness and strength of the pipe material without causing permanent deformation -3-7.
Q5: What does "Hardness" refer to in carbon steel, and why is it important for sour service (H2S)?
A5: Hardness is the resistance to indentation. In sour service (H2S environments), NACE MR0175 imposes maximum hardness limits to prevent Sulfide Stress Cracking (SSC) -9.
