1. Q: What is ASTM A333 Grade 1?
A:
It is a low-temperature carbon steel pipe designed for low-temperature environments (down to -45°C).
Its chemical composition is primarily low-carbon (≤0.30% C), with small amounts of elements such as manganese and silicon to ensure low-temperature toughness.
Normalizing heat treatment optimizes the grain structure to prevent low-temperature brittle cracking.
2. Q: What are its main applications?
A:
Cryogenic piping systems: such as liquefied natural gas (LNG) and liquid nitrogen/liquid oxygen transportation.
Petrochemical industry: Refrigeration equipment and cryogenic storage tank piping.
Power industry: Cryogenic heat exchangers and boiler auxiliary piping.
3. Q: What are the key mechanical performance indicators?
A (typical values):
Tensile strength: ≥380 MPa
Yield strength: ≥205 MPa
Elongation: ≥35% (50mm gauge length)
Impact test: Must meet Charpy V-notch impact requirements at -45°C (typically ≥20J).
4. Q: What is the difference between A333 Grade 1 and ordinary carbon steel pipe (such as ASTM A106)?
A:
Low-temperature toughness: A333 Grade 1 passes rigorous impact testing, while ordinary steel pipe may become brittle at low temperatures.
Heat treatment: A333 requires normalizing, while A106 generally does not.
Application differences: A106 is suitable for high-temperature applications (such as steam pipes), while A333 is specialized for low-temperature applications.
5. Q: What precautions should be taken during processing and welding?
A:
Welding process: Low-hydrogen electrodes (such as E7018) are recommended, and preheating to 100-150°C is recommended to prevent cold cracking. Cold bending restrictions: The bend radius must be ≥ 3 times the pipe diameter to avoid excessive deformation that may reduce toughness.
Post-cutting treatment: Grind away burrs to reduce stress concentration points.
