ASTM A333 Gr.6 Carbon Steel Seamless Tube for Low-temperature Service

Comparison with Other Low-Temperature Carbon Steels (Within A333/A334)

*Takeaway: Within the low-temperature carbon steel family, A333 Gr.6 is the workhorse for the -45°C range. Choose a higher grade (Gr.3, Gr.8) for lower temperatures, and consider Gr.1 (welded) or A334 (tubing) for different product forms.

ASTM A333 Gr.6 Carbon Steel Seamless Tube Equivalent Grades

ASTM A333 Gr.6 Carbon Steel Seamless Tube Chemical Properties

ASTM A333 Gr.6 Carbon Steel Seamless Tube Mechanical Properties

*Impact Toughness (Charpy V-Notch) Requirements:

• Test Temperature: -50°F (-45°C).

• Minimum Average Energy: 13 ft-lbf (18 J) for a set of three specimens.

• Minimum Single Value: 10 ft-lbf (14 J).

• Specimen Size: Standard full-size (10mm x 10mm). If sub-sized specimens must be used due to thin walls, the required energy values are proportionally reduced.

Testing & Inspection Requirements (Typical for Seamless)

1. Hydrostatic Test: Every length of pipe must be tested to a specified pressure without leakage.

2. Non-Destructive Electric Test (NDE): Seamless pipe is typically subjected to an eddy current test or ultrasonic test to detect major longitudinal imperfections.

3. Flattening Test, Flange Test, or Reverse Bend Test: One of these is performed on seamless pipe to check ductility.

4. Chemical Analysis: Check of ladle or product analysis.

5. Tension Test: To verify mechanical properties.

6. Impact Test (CVN): Mandatory for A333 Gr.6. Tests are performed on heats of steel and often by lot.

Applications

A333 Gr.6 seamless tubes are used in critical low-temperature process piping and equipment:

• Liquefied Natural Gas (LNG) facilities

• Cryogenic processing plants

• Refrigeration systems

• Cold storage piping

• Skid-mounted process units for oil & gas in cold climates

• Ammonia and ethylene transport lines