What Is ASTM A333 Grade 6 Pipe Material?
ASTM A333 Grade 6 is a low-temperature carbon steel pipe specification developed by ASTM International for cryogenic service. The standard covers seamless and welded pipe in several grades; Grade 6 is the most widely used, combining good low-temperature impact toughness with practical strength and weldability. It is the default material for piping systems that operate down to approximately -45°C.
Key Material Properties
Low-temperature impact toughness:
reliable Charpy impact performance at sub-zero temperatures, preventing brittle fracture.
Good strength:
sufficient yield and tensile strength for pressurized low-temperature systems.
Corrosion resistance:
adequate for many hydrocarbon and chemical media in cryogenic service.
Weldability:
weldable with appropriate low-temperature qualified procedures.
Standard Requirements
| Item | ASTM A333 Gr.6 |
|---|---|
| Minimum tensile strength | 415 MPa (60,200 psi) |
| Minimum yield strength | 240 MPa (35,000 psi) |
| Impact test temperature | -45°C (typical) |
| Forms | Seamless and welded, cold-drawn or hot-finished |
Applications
LNG, LPG and ethylene plants
Cryogenic storage and transport systems
Petrochemical cold sections and heat exchangers
Power generation low-temperature circuits
Air separation units
Frequently Asked Questions
What temperature can A333 Gr.6 handle?
Grade 6 is typically rated for service down to -45°C; lower temperatures require austenitic stainless or 9% nickel steels.
Is A333 Gr.6 seamless or welded?
Both. A333 covers seamless and welded pipe; seamless is common for small diameters and high integrity.
What is the difference between A333 Gr.6 and A106 Gr.B?
A333 Gr.6 is impact-tested for low-temperature service, while A106 Gr.B is a high-temperature seamless pipe without mandatory sub-zero toughness.
Can A333 Gr.6 be welded?
Yes, with qualified low-temperature welding procedures and low-hydrogen consumables.
Is impact testing required?
Yes. Charpy V-notch impact tests at the specified temperature are mandatory under the standard.
