Key Feature

The Low-Carbon Welding-Grade Piping Solution. Maximum 0.03% carbon prevents sensitization in welded structures, ensuring maintained corrosion resistance in heat-affected zones.

Essential for welded piping systems where post-weld heat treatment is impractical or impossible.

Common Designations

UNS S30403
AISI 304L
ASTM A312 (Seamless/Welded Pipe)ASTM A358 (EFW Pipe)
EN 1.4307, X2CrNi18-9
JIS SUS304L

ASTM A312 TP304L is the primary pressure pipe specification.

Chemical Composition (Typical wt.%)

C: ≤ 0.030Cr: 18.0 - 20.0
Ni: 8.0 - 12.0
Mn: ≤ 2.00
Si: ≤ 0.75
P: ≤ 0.045
S: ≤ 0.030

Ultra-low carbon (≤0.03%) is the defining characteristic versus standard 304 (≤0.08%).

Mechanical Properties

Tensile Strength: ≥ 485 MPa
Yield Strength: ≥ 170 MPa
Elongation: ≥ 40%
Hardness: ≤ 201 HB

Slightly lower yield strength than standard 304, but adequate for most piping applications.

Physical Properties

Density: 7.93 g/cm³
Melting Range: 1399 - 1454 °C
Thermal Expansion: 17.2 × 10⁻⁶/K (20-100°C)
Non-magnetic when annealed

Identical physical properties to standard 304 stainless steel.

Pressure Ratings

Schedule 5S: 0.065" wall (NPS 1/2)
Schedule 10S: Standard light wall
Schedule 40S: Standard weight
Schedule 80S: Extra strong
Per ASME B36.19

Same dimensional standards as 304; pressure ratings calculated using lower yield strength.

Corrosion Resistance

Excellent general corrosion resistance identical to 304. Superior resistance to intergranular corrosion in welded conditions and after exposure to sensitizing temperatures.

Maintains full corrosion resistance in weld heat-affected zones—critical advantage over standard 304.

Temperature Limits

Continuous Service: Up to 425°C (for corrosion resistance)
Higher Temp Service: Up to 870°C with possible sensitization
Cryogenic Service: Excellent down to -196°C

Lower maximum temperature for corrosion service than 304, but better weld performance.

Welding Advantages

• No Sensitization in weld HAZ
• No Post-Weld Annealing required
• Maintains Corrosion Resistance• Suitable for Heavy Sections• All Welding Methods applicable

Eliminates need for costly post-weld heat treatment in most applications.

Key Standards

ASTM A312 TP304L: Seamless & Welded Pipe
ASTM A358 TP304L: EFW Pipe
ASTM A269 TP304L: Tubing
ASTM A789/A790: General Service Pipe
EN 10216-5: Seamless Pressure Tubes
ASME SA312: Code Construction

ASME Boiler and Pressure Vessel Code acceptance for critical applications.

Common Applications

• Chemical Processing: Welded process piping, reactor systems, corrosive service lines
• Pharmaceutical: Clean utility piping, WFI systems, process lines requiring extensive welding
• Food & Beverage: Welded process systems, CIP lines, product transfer piping
• Oil & Gas: Corrosive service piping, chemical injection lines, offshore applications
• Power Generation: Fine gas desulfurization systems, chemical feed lines
• Pulp & Paper: Digester lines, bleach plant piping, chemical recovery systems
• Environmental: Scrubber systems, wastewater treatment piping, pollution control

Specifically selected where welding integrity and maintained corrosion resistance are critical.