Q: What is "sour service" pipe, and what special properties does it need?
A: For environments containing H2S. It requires controlled hardness, enhanced cleanliness (low S, P), and often specific microstructure to resist Sulfide Stress Cracking (SSC).
Q: What does "DSAW" mean, and where is it used?
A: Double Submerged Arc Welded. The weld is made from both inside and outside. Used for heavy-wall, large-diameter, high-pressure applications.
Q: Why are welded pipes sometimes preferred for structural columns?
A: They can be made in square and rectangular hollow sections (SHS/RHS) with efficient, aesthetic profiles and good strength-to-weight ratio.
Q: What is the typical weld seam defect that UT is excellent at finding?
A: Planar defects like cracks, lack of fusion, and laminations that are perpendicular to the surface.
Q: What is the "HAZ" and why is it important?
A: The Heat-Affected Zone is the base metal region whose microstructure is altered by welding heat. It can be a zone of weakness with reduced toughness or increased hardness.
Q: What is "cold welding" in the context of ERW?
A: An ERW defect where insufficient heat during welding causes poor forge and a weak bond, often detectable by UT.
