1. Q: When is submerged arc welding (SAW) used for pipe?
A: For heavy-wall, large-diameter pipes (often > 24 inches) where high-quality, deep-penetration welds are required for high-pressure applications like oil and gas transmission.
2. Q: What is a "killed" carbon steel?
A: Steel that has been fully deoxidized during melting, resulting in a more uniform structure and fewer defects, making it suitable for pipes for pressure applications.
3. Q: What is the purpose of heat treatment on welded pipes?
A: To normalize or stress-relieve the weld area, refining the grain structure and relieving internal stresses from welding, improving mechanical properties.
4. Q: What is a common non-destructive test for weld seams?
A: Ultrasonic Testing (UT) or Eddy Current Testing (ECT) are commonly used to detect flaws in ERW and seamless pipes.
5. Q: What is hydrostatic testing of pipe?
A: Filling the pipe with water and pressurizing it to a specified level to proof-test its strength and leak integrity.
