What Is the Composition of ASME SA-213 TP304?

What ASME SA-213 / ASTM A213 Covers

ASME SA-213 is identical in technical content to ASTM A213 and covers seamless ferritic and austenitic steel boiler, superheater, and heat exchanger tubes. The specification is seamless only; welded tubes for similar service are covered by ASTM A249 (austenitic welded boiler and heat exchanger tubes) or A269 (general-service tubing). For pressure equipment built to the ASME Boiler and Pressure Vessel Code, material is ordered to SA-213, while non-code projects commonly reference A213. TP304 is the base 18-8 austenitic grade of this specification family.

Chemical Composition of TP304

Element	TP304 limit (%, by weight)
Carbon	max 0.08
Manganese	max 2.00
Phosphorus	max 0.045
Sulfur	max 0.030
Silicon	max 1.00
Chromium	18.0-20.0
Nickel	8.0-11.0

The 18-8 chromium-nickel balance gives TP304 its austenitic structure, corrosion resistance, and good fabrication behavior. The 0.08% carbon limit keeps sensitization risk manageable for most boiler and exchanger service; where welding is extensive or service temperatures are high, specify the L- or H-variants below.

Heat Treatment and Mechanical Properties

Property	Requirement
Heat treatment	Solution annealed, min 1900 °F (1040 °C), quenched
Tensile strength, min	75 ksi (515 MPa)
Yield strength, min	30 ksi (205 MPa)
Elongation, min	35%

Solution annealing dissolves chromium carbides and restores full corrosion resistance. The quench must be rapid enough to avoid re-precipitation in the 450-850 °C range during cooling.

Grade Variants in the Same Standard

TP304H: higher minimum carbon (0.04-0.10%) for better creep strength above 500 °C in superheaters.

TP316 / TP316L: 2-3% molybdenum for chloride resistance; TP316H for high-temperature creep service.

TP321 / TP321H: titanium-stabilized for high-temperature service without sensitization.

TP347 / TP347H: niobium-stabilized, preferred for long-term high-temperature creep and thermal cycling.

TP310 / TP310S: 25Cr-20Ni for furnace and oxidation service up to about 1000 °C.

Applications

Boiler superheater and reheater tubes in power plants.

Feedwater heaters, condensers, and heat exchangers in refineries and chemical plants.

High-pressure steam lines and instrumentation tubing where corrosion resistance and clean bore are required.

Common Misconceptions

'SA-213 covers welded tubes.' No. A213/SA-213 is seamless only; welded boiler and heat exchanger tubes are covered by ASTM A249.

'TP304 and TP304H are the same.' TP304H has a controlled higher carbon range (0.04-0.10%) for improved creep strength at elevated temperature.

'Any 304 pipe meets SA-213.' SA-213 has its own heat treatment, testing, and dimensional requirements; 304 pipe to A312 or A269 is a different product with different certification.

Frequently Asked Questions

What is the chemical composition of SA-213 TP304?

Chromium 18.0-20.0%, nickel 8.0-11.0%, carbon max 0.08%, manganese max 2.00%, silicon max 1.00%, phosphorus max 0.045%, sulfur max 0.030%.

What does TP stand for in TP304?

TP denotes the tube product form in the A213 designation system, distinguishing it from plate or bar grades of the same nominal composition.

What is the difference between ASTM A213 and ASME SA-213?

A213 is the ASTM standard; SA-213 is the same specification adopted by ASME for pressure equipment built to the Boiler and Pressure Vessel Code. Technical requirements are equivalent.

Is SA-213 TP304 seamless or welded?

Seamless. A213/SA-213 covers only seamless tubes; for welded equivalents use ASTM A249 (boiler and heat exchanger) or A269 (general service).

What heat treatment does TP304 require?

Solution annealing at a minimum of 1900 °F (1040 °C) followed by quenching, to dissolve carbides and restore corrosion resistance.

When should I choose TP304H instead of TP304?

When the tube operates above about 500 °C and creep strength governs the design; the higher carbon range of TP304H (0.04-0.10%) improves long-term high-temperature strength.