TP310MoLN Seamless Stainless Steel Tube

UNS S31050 | 1.4466 | ASTM A213

TP310MoLN Seamless Stainless Steel Tube (S31050 / 1.4466) 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 TP310MoLN Tube?

TP310MoLN (UNS S31050) is a high-alloy austenitic stainless steel developed specifically for urea-grade service. Its fully austenitic, non-magnetic structure combined with high chromium, molybdenum and nitrogen delivers exceptional resistance to urea carbamate corrosion and to chloride stress-corrosion cracking, making it a standard material for urea strippers, carbamate condensers and high-pressure synthesis equipment.

Seamless TP310MoLN stainless steel tube (UNS S31050 / W.Nr. 1.4466) is a high-alloy, nitrogen-enhanced austenitic stainless steel specifically developed for extreme corrosion environments, particularly in urea synthesis and chloride-rich systems.

Produced via seamless hot extrusion and precision cold finishing, the product ensures:

The “MoLN” designation represents:

TP310MoLN is widely recognized as a premium urea-grade stainless steel tube, especially for ammonium carbamate service environments.

TP310MoLN Key Features and Technical Advantages

Designed for urea synthesis plants, TP310MoLN provides outstanding resistance to:

High alloy content significantly improves corrosion resistance:

Result: High PREN (Pitting Resistance Equivalent Number), far exceeding 316L and 310.

Feature	Description
Exceptional Urea Carbamate Resistance	Ammonium carbamate Urea solutions High-pressure CO₂/NH₃ environments
Superior Corrosion Resistance (High PREN)	~25% 2.5% – 3.5% Nitrogen addition enhances stability
Excellent Resistance to SCC (Stress Corrosion Cracking)	Strong resistance to chloride-induced SCC Reliable performance in marine, offshore, and desalination systems
High Mechanical Strength	Yield strength Load-bearing capacity Design stress limits
Fully Austenitic & Non-Magnetic	Stable austenitic microstructure Excellent cold working capability Non-magnetic in annealed condition

TP310MoLN 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 TP310MoLN .

The composition of Stainless Steel TP310MoLN is carefully balanced to achieve its superior corrosion resistance and high strength.

Table 1: Chemical Composition of Stainless Steel 310MoLN

Cr	Ni	Mo	N	P	S	Mn	Si	C
24.00 - 26.00	20.50 - 23.50	1.60 - 2.60	0.09 - 0.15	≤ 0.020	≤0.010	≤ 2.00	≤ 0.40	≤ 0.020

Stainless Steel TP310MoLN is specifically designed to maintain its strength and shape in high-stress, corrosive environments.

Table 2: Typical Mechanical Properties of Stainless Steel TP310MoLN

Tensile Strength	Yield Strength	Elongation	Hardness	Brinell Hardness
≥ 690 MPa	≥ 310 MPa	≥ 35%	≤ 217 HBW	≤217 HB

These physical properties highlight the material's ability to perform reliably under a wide range of conditions.

Table 3: Typical Physical Properties of Stainless Steel TP310MoLN

Density	Melting Point	Thermal Expansion	Thermal Conductivity	Modulus of Elasticity	Electrical Resistivity
8.0 g/cm³	1390 - 1440 °C approx.	16.5 µm/m·°C (20-100°C)	16.0 W/m·K (20°C)	193 GPa	0.74 x 10⁻⁶ Ω·m (20°C)

TP310MoLN Dimensional Standards and Tolerances

TP310MoLN seamless tubes are supplied to the dimensional tolerances of ASTM A213 / A1016 unless a tighter project specification applies.

Table 4: The Standard of Stainless Steel Seamless Tube Size Tolerance Size Chart :

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

TP310MoLN Common Industrial Applications

Industry	Typical Applications
Urea and Fertilizer Industry	Urea strippers and carbamate condensers High-pressure synthesis equipment Urea reactor internals
Oil and Gas / Offshore	Process and utility piping Chloride-bearing service lines Offshore platform equipment
Marine and Desalination	Seawater systems Desalination plant piping Brine handling equipment
Pulp and Paper Industry	Bleach plant equipment Digester and liquor lines Heat exchangers

TP310MoLN Quality Assurance and Production Process

Process Step	Description
Certification	All TP310MoLN (UNS S31050) tubes are supplied to ASTM A213 / ASME SA213 and ASTM A312 / ASME SA312 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.

TP310MoLN vs TP316L / TP310 – Technical Comparison

TP310MoLN is a specialised high-alloy austenitic grade developed for urea service. Comparing it with TP316L and TP310 clarifies its niche.

Chemical Composition

TP316L: 2–3% Mo, no nitrogen addition, carbon 0.030% maximum
TP310: 24–26% Cr, 19–22% Ni, no molybdenum, no nitrogen
TP310MoLN (S31050): ~25% Cr, ~22% Ni, 2–3% Mo, 0.10–0.16% N, fully austenitic

Urea Carbamate Resistance

TP310MoLN was developed specifically to resist urea carbamate corrosion, the failure mode that governs urea stripper and carbamate condenser life. Neither TP316L nor TP310 has the combination of molybdenum, nitrogen and fully austenitic structure required for that duty.

Chloride Stress-Corrosion Resistance

The combination of high chromium, molybdenum and nitrogen gives TP310MoLN excellent resistance to chloride stress-corrosion cracking, better than TP316L and comparable to the other high-alloy austenitic grades. It is also fully non-magnetic.

Selection Guide

Choose TP310MoLN for urea synthesis equipment — strippers, carbamate condensers and high-pressure internals
Choose TP316L for general corrosion service where neither urea nor severe chloride duty applies
Choose TP310 where high-temperature oxidation resistance is the requirement and molybdenum is not needed

Frequently Asked Questions About TP310MoLN Seamless Stainless Steel Tubes

What is TP310MoLN tube?

TP310MoLN (UNS S31050) is a high-alloy, fully austenitic stainless steel tube developed specifically for urea-grade service. Its chromium, molybdenum and nitrogen content delivers exceptional resistance to urea carbamate corrosion.

Why is TP310MoLN used in urea plants?

Urea synthesis equipment operates with carbamate solutions that attack most stainless steels. TP310MoLN's combination of molybdenum, nitrogen and a fully austenitic non-magnetic structure resists that attack, and its low carbon content allows thick sections to be welded without sensitisation.

What standard covers TP310MoLN tube?

TP310MoLN seamless tube is supplied to ASTM A213 / ASME SA213 and ASTM A312 / ASME SA312, with dimensional tolerances per ASTM A1016 / A1016M.

What is TP310MoLN tube used for?

TP310MoLN is used for urea strippers and carbamate condensers, high-pressure synthesis equipment and reactor internals, plus chloride-bearing process lines in oil and gas, marine and desalination service.

Request a TP310MoLN Tube Quotation

Send your Seamless Stainless Steel TP310MoLN Tube enquiry with grade, application, size (OD and wall thickness or schedule), quantity, length, end finish and inspection requirements including any urea-grade or corrosion test documentation required.

Request a TP310MoLN Tube Quotation