Q: What type of welded pipe is used for extremely high temperatures in furnaces, often with a centrifugally cast method?
A: Heat-Resistant Alloy grades like HK-40 (25Cr-20Ni) or similar alloys per ASTM A608, though these are often cast rather than welded from plate/coil.
F. Line Pipe (Oil & Gas Transmission)
Q: What is the primary API specification for welded steel line pipe?
A: API 5L. It covers both seamless and welded (ERW, SAW, etc.) pipe for conveying gas, water, and oil.
Q: In API 5L, what does the "X" denote in grades like X42, X65, or X80?
A: The "X" denotes a grade with a specified minimum yield strength (SMYS) in ksi (thousand pounds per square inch). X42 has 42 ksi SMYS, X65 has 65 ksi, etc.
Q: What is the key difference between API 5L PSL1 and PSL2 pipe?
A: PSL2 (Product Specification Level 2) has more stringent requirements than PSL1, including tighter chemistry control, higher toughness (Charpy testing), mandatory hydrostatic testing, and stricter non-destructive examination.
Q: What is a common high-strength, thermo-mechanically controlled processed (TMCP) grade for modern high-pressure pipelines?
A: API 5L X70 or X80 in PSL2. These high-strength steels allow for larger diameters and higher pressures with thinner walls.
