TP904L Seamless Stainless Steel Tube

UNS N08904 | 1.4539 | ASTM A213

TP904L Seamless Stainless Steel Tube (N08904 / 1.4539) is manufactured to ASTM A213 from stainless steel billet, cold-drawn to the required outside diameter and wall thickness. Supplied from our Wenzhou mill with EN 10204 3.1 mill test certificate, PMI and dimensional inspection on request.

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What Is a Seamless Stainless Steel TP904L Tube?

TP904L (UNS N08904) is a super austenitic stainless steel with 25% nickel, 20% chromium, 4.5% molybdenum and 1.5% copper. The high nickel content stabilises the austenitic structure and the copper addition improves resistance to sulphuric and phosphoric acids, giving TP904L a broad corrosion envelope spanning both oxidising and moderately reducing media.

Seamless TP904L stainless steel tube (UNS N08904 / W.Nr. 1.4539) is a high-alloy super austenitic stainless steel tube engineered for the most aggressive corrosive environments, particularly sulfuric acid (H₂SO₄) and mixed acid media.

Produced from a solid billet using a seamless process (hot piercing + cold drawing/finishing), TP904L provides:

The grade is characterized by:

This unique composition ensures excellent resistance to reduction acids, especially sulfuric acid, while maintaining weldability and structural stability.

TP904L Key Features and Technical Advantages

Outstanding Sulfuric Acid Resistance Specifically engineered for sulfuric acid service across a wide concentration range (under moderate temperatures). Also performs well in phosphoric acid and acetic acid environments.

Excellent Pitting & Crevice Corrosion Resistance High Mo (4–5%) and Cu content significantly improve resistance to localized corrosion, with a high PREN (Pitting Resistance Equivalent Number).

Superior Resistance to Chloride SCC Nickel content (23–28%) provides strong resistance to chloride-induced stress corrosion cracking (SCC), making it suitable for marine and industrial environments.

Feature	Description
Outstanding Sulfuric Acid Resistance	Specifically engineered for sulfuric acid service across a wide concentration range (under moderate temperatures). Also performs well in phosphoric acid and acetic acid environments.
Excellent Pitting & Crevice Corrosion Resistance	High Mo (4–5%) and Cu content significantly improve resistance to localized corrosion, with a high PREN (Pitting Resistance Equivalent Number).
Superior Resistance to Chloride SCC	Nickel content (23–28%) provides strong resistance to chloride-induced stress corrosion cracking (SCC), making it suitable for marine and industrial environments.
Excellent Weldability & Fabricability	Low carbon content prevents sensitization, ensuring corrosion resistance in the heat-affected zone (HAZ) without the need for post-weld heat treatment.
Non-Magnetic Austenitic Structure	Remains non-magnetic even after cold working, suitable for specialized industrial and electronic applications.

TP904L Product Specifications and Data

To provide a comprehensive overview of this high-performance material, here are the detailed technical specifications and performance data for Stainless Steel 904L.

The composition of Stainless Steel 904L is carefully balanced to achieve its superior corrosion resistance and high strength.

Cr	Ni	P	S	Mo	Cu	Mn	Si	C
19.00 - 23.00	23.00 - 28.00	≤ 0.040	≤ 0.030	4.00 - 5.00	1.00 - 2.00	≤ 2.00	≤ 1.00	≤ 0.02

Key Element: Copper (Cu) enhances resistance to sulfuric acid corrosion, making TP904L a preferred material for acid processing industries.

Tensile Strength	Yield Strength	Elongation	Hardness
≥ 490 MPa	≥ 215 MPa	≥ 35%	≤ 192 HBW

Density	Melting Point	Thermal Expansion	Thermal Conductivity	Modulus of Elasticity	Electrical Resistivity
8.0 g/cm³	1300 - 1390 °C approx.	16.5 µm/m·°C (20-100°C)	13.9 W/m·K (20°C)	195 GPa	0.85 x 10⁻⁶ Ω·m (20°C)

Standard	OD(D)	Tolerance（MM)		Thickness(S)	Tolerance(MM)	Length	Tolerance
Standard	MM	Common	High	MM	Tolerance(MM)	Length	MM
EN 10216-5 HFD	30≤D≤219.1（D2)	±1.0% or ±0.5mm, whicever is the greater		T1, T≤4	±15% or ±0.6mm, whicever is the greater	L≤6M	+5/0
	30≤D≤219.1（D2)	±1.0% or ±0.5mm, whicever is the greater		T2	±12.5% or ±0.4mm, whicever is the greater	L≤6M	+5/0
	219.1≤D≤610 (D1)	±1.5% or ±0.75mm, whicever is the greater		T≤0.05D	+22.5%/-15%	6＜l≤12	+10/0
				T1, 0.05D＜t≤0.09D	±15% or ±0.6mm, whicever is the greater	6＜l≤12	+10/0
				T2, T>0.09D	±12.5% or ±0.4mm, whicever is the greater	L>12	+by agreement/0
EN 10216-5 CFD	D3(D≤219.1)	±0.75% or ±0.3mm, whicever is the greater		T3	±10% or ±0.2mm, whicever is the greater
EN 10216-5 CFD	D4(D≤219.1)	±0.5% or ±0.mm, whicever is the greater		T4	±7.5% or ±0.15mm, whicever is the greater
ASTM A213 HFD	D≤100	+0.4/-0.8		D＜100,S≤2.4	+40%/0	HFD, all size	+5.0/0
		+0.4/-1.2		D＜100,2.4＜s≤3.8	+35%/0
		+0.4/-1.6		D＜100,3.8＜s≤4.6	+33%/0
		+0.4/-1.6		D＜100,S>4.6	+28%/0
	100＜d≤200	+0.4/-1.2		D>100, 2.4＜s≤3.8	+35%/0
	200＜d≤225	+0.4/-1.6		D>100,3.8＜s≤4.6	+33%/0
	200＜d≤225	+0.4/-1.6		D>100,S>4.6	+28%/0
ASTM A213 CFD	D＜25	±0.10		D≤38.1	+20%/0	CFD, D＜50.8	+3.0/0
	25≤D≤40	±0.15
	40＜d＜50＜ span="">	±0.20
	50≤D＜65	±0.25
	65≤D＜75	±0.30		D>38.1	+22%/0	CFD, D≥50.8	+5.0/0
	75≤D≤100	±0.38
	100＜d≤200	+0.38/-0.64
	200＜d≤225	+0.38/-1.14
ASTM A269	D≤13	±0.13		D≤13	±15%	D＜38	+3.2/0
	13＜d＜38＜ span="">	±0.13		13＜d＜356＜ span="">	±10%	D＜38	+3.2/0
	38≤D＜89	±0.25				D>38	+4.8/0
	89≤D＜140	±0.38
	140≤D＜203	±0.76
	203≤D＜305	±1.01
	305≤D＜356	±1.26
ASTM A270	D＜25	±0.13		For weld pipe all size	±12.5%		+3.0/0
	25-50	±0.20
	50-75	±0.25
	75-100	±0.38		For CD SMLS pipe D≤38.1	+20%/0
	100-140	±0.38		For CD SMLS pipe D≤38.1	+20%/0		+5.0/0
	140-200	±0.75		For CD SMLS pipe D>38.1	+22%/0
	200-300	±1.25		For CD SMLS pipe D>38.1	+22%/0

TP904L Dimensional Standards and Tolerances

TP904L seamless tubes are supplied to the dimensional tolerances of ASTM B829 / B677 unless a tighter project specification applies.

TP904L Common Industrial Applications

Industry	Typical Applications
Chemical and Acid Processing	Sulphuric and phosphoric acid plants Reactors and heat exchangers Acid storage and transfer lines
Oil and Gas / Refinery	Process piping and heat exchangers Desalination and utility systems Offshore equipment
Environmental Engineering	Flue gas desulphurisation systems Wastewater treatment plant Effluent handling pipework
Pulp and Paper Industry	Bleach plant equipment Digester and liquor lines Heat exchangers
Pharmaceutical and Food Industry	Sanitary process piping Heat exchanger tubing Corrosive media transfer

TP904L Quality Assurance and Production Process

Process Step	Description
Certification	All TP904L (UNS N08904) tubes are supplied to ASTM B677 / ASME SB677 and ASTM B673 / ASME SB673 with EN 10204 3.1 mill test certificates. Third-party inspection (SGS, BV, TUV, Lloyd's), PMI reports and full heat-number traceability can be provided on request.
Non-Destructive Testing (NDT)	Hydrostatic or eddy-current testing is performed on 100% of tubes. Ultrasonic testing (UT) and dye-penetrant inspection (PT) are available for critical service, with records retained for each production lot.
Material Verification	Positive Material Identification (PMI) and spectrometric analysis confirm that the chemical composition matches the ordered grade and that the ferrite/austenite balance is within the specified range.
Mechanical Testing	Tensile, yield, elongation and hardness tests are carried out per heat. Impact testing can be supplied at the project design temperature for subsea and low-temperature service.
Dimensional Inspection	Outside diameter, wall thickness, ovality and straightness are measured against ASTM A1016 / A1016M or ASTM A789 tolerances. Length, square-cut ends and end-finish conditions are verified before packing.

TP904L vs TP316L / 254SMO – Technical Comparison

TP904L is a super austenitic grade with unusually high nickel. Comparing it with TP316Land254SMO shows what the extra nickel and copper buy.

Chemical Composition

TP316L: 16–18% Cr, 10–14% Ni, 2–3% Mo — the general-purpose grade
TP904L (N08904): 19–23% Cr, 23–28% Ni, 4–5% Mo, 1.0–2.0% Cu
254SMO (S31254): 20% Cr, 18% Ni, 6% Mo, 0.2% N — higher molybdenum

Acid Resistance

The high nickel content of TP904L stabilises the austenitic structure and the copper addition specifically improves resistance to sulphuric and phosphoric acid. This combination gives TP904L a broader acid envelope than TP316L, and better performance in reducing acid conditions than the higher-molybdenum but lower-nickel 254SMO.

Chloride Resistance

254SMO's 6% molybdenum gives it the higher critical pitting temperature and therefore the advantage in chloride service. TP904L resists chlorides well but is not the first choice for seawater duty.

Selection Guide

Choose TP904L for sulphuric and phosphoric acid plants, and for mixed acid service where copper-bearing chemistry helps
Choose 254SMO for seawater, brine and high-chloride streams
Choose TP316L where neither acid nor chloride duty is severe

Frequently Asked Questions About TP904L Seamless Stainless Steel Tubes

What is TP904L tube?

TP904L (UNS N08904) is a super austenitic stainless steel tube with 25% nickel, 20% chromium, 4.5% molybdenum and 1.5% copper. The high nickel content stabilises the austenitic structure and the copper improves resistance to sulphuric and phosphoric acids.

What is the advantage of TP904L over TP316L?

TP904L's higher nickel, chromium and molybdenum contents give it a much broader corrosion envelope, with significantly better performance in sulphuric and phosphoric acid and in chloride-bearing process streams. TP316L is limited to general corrosion-resistant service.

What standard covers TP904L tube?

TP904L seamless tube is supplied to ASTM B677 / ASME SB677 for seamless tube and ASTM B673 / ASME SB673 for welded pipe, with ASTM B829 covering general requirements.

What is TP904L tube used for?

TP904L is used for sulphuric and phosphoric acid plants, refinery process piping and heat exchangers, flue-gas desulphurisation systems, pulp and paper bleach plants and pharmaceutical process equipment.

Request a TP904L Tube Quotation

Send your Seamless Stainless Steel TP904L Tube enquiry with grade, application, size (OD and wall thickness or schedule), quantity, length, end finish and inspection requirements. Our technical team will confirm availability, testing scope and lead time.

Request a TP904L Tube Quotation