UNS S31600|1.4401|TP316 Seamless Stainless Steel Tube

Seamless Stainless Steel TP316 Tubes (UNS S31600 / W.Nr. 1.4401) are premium-grade austenitic solutions engineered for exceptional mechanical strength and superior corrosion resistance in chloride-rich environments. As a premier manufacturer based in Wenzhou, China, XinZhe produces high-integrity seamless tubing that strictly adheres to ASTM A312, ASTM A213, and ASME SA213 international standards.

Distinguished by its strategic Molybdenum content (2-3%), our TP316 tubing provides significantly enhanced resistance to pitting and crevice corrosion compared to standard 304 grades. These tubes are indispensable for mission-critical applications in marine hardware, chemical reactors, and pharmaceutical processing equipment. Through advanced cold-drawing and precise solution annealing, XinZhe ensures every tube maintains a uniform microstructure and excellent surface finish, delivering reliable performance for the most demanding global industrial needs.

"For applications involving extensive welding, we also provide TP316L (UNS S31603) with lower carbon content to prevent sensitization and maintain intergranular corrosion resistance."

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What Is a Seamless Stainless Steel TP316 Tube?

Seamless TP316 (UNS S31600 / W.Nr. 1.4401) tube is the molybdenum-bearing austenitic stainless steel that extends the corrosion performance of the 304 grade into chloride-bearing and reducing-acid environments. The 2–3% molybdenum addition raises the pitting resistance equivalent number and markedly improves resistance to pitting and crevice attack in seawater and process streams.

Seamless Stainless Steel TP316 tube (UNS S31600) is a molybdenum-alloyed austenitic stainless steel tubing manufactured through a seamless process to ensure maximum structural integrity and corrosion resistance.

Unlike welded tubes, the seamless construction eliminates weld seams, providing uniform mechanical properties and enhanced reliability under high pressure, corrosive media, and critical service conditions.

The defining feature of Grade 316 stainless steel is its 2.0% – 3.0% molybdenum (Mo) content, which significantly improves resistance to pitting and crevice corrosion, especially in chloride-rich environments such as seawater, chemical processing, and offshore applications.

Key Features and Technical Advantages

The addition of molybdenum provides enhanced protection against localized corrosion, making TP316 far more resistant than TP304 in aggressive environments.

Seamless manufacturing eliminates weld defects, allowing higher allowable stress values in accordance with ASME Boiler and Pressure Vessel Code (BPVC).

TP316 offers outstanding weldability, formability, and machinability, suitable for complex piping systems using standard TIG/MIG processes.

Superior Pitting and Crevice Corrosion Resistance

The addition of molybdenum provides enhanced protection against localized corrosion, making TP316 far more resistant than TP304 in aggressive environments.

High-Pressure Capability (Seamless Structure)

Seamless manufacturing eliminates weld defects, allowing higher allowable stress values in accordance with ASME Boiler and Pressure Vessel Code (BPVC).

Excellent Fabrication Performance

TP316 offers outstanding weldability, formability, and machinability, suitable for complex piping systems using standard TIG/MIG processes.

Hygienic Surface Quality

Smooth internal surfaces reduce contamination risks, making it ideal for food processing and pharmaceutical industries requiring high cleanliness standards.

Cryogenic Toughness

Maintains excellent ductility and impact resistance at sub-zero temperatures, suitable for low-temperature and LNG applications.

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 316.

The composition of Stainless Steel 316 is carefully balanced to achieve its superior corrosion resistance and high strength.

Table 1: Chemical Composition of Stainless Steel 316

Cr	Ni	Mo	P	S	Mn	Si	C
16.00 - 18.00	10.00 - 14.00	2.00 - 3.00	≤ 0.045	≤ 0.030	≤ 2.00	≤ 1.00	≤ 0.08

Stainless Steel 316 is specifically designed to maintain its strength and shape in high-stress, corrosive environments.

Table 2: Typical Mechanical Properties of Stainless Steel 316

Tensile Strength	Yield Strength	Elongation	Hardness
≥ 515 MPa	≥ 205 MPa	≥ 35%	≤ 192 HBW

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 316

Density	Melting Point	Thermal Expansion	Thermal Conductivity	Modulus of Elasticity	Electrical Resistivity
8.0 g/cm³	1375 - 1400 °C approx.	16.5 µm/m·°C (20-100°C)	16.3 W/m·K (20°C)	193 GPa	0.74 x 10⁻⁶ Ω·m (20°C)

Dimensional Standards and Tolerances

TP316 seamless tubes are produced to the dimensional tolerances of ASTM A213 / A213M, ASTM A269 and ASTM A312, with inspection per ASTM A1016 / A1016M.

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

Standard	OD(D)	Tolerance（MM)		Thickness(S)	Tolerance(MM)	Length	Tolerance
	MM	Common	High	MM			MM
EN 10216-5 HFD	30≤D≤219.1（D2)	±1.0% or ±0.5mm, whicever is the greater(取较大者)		T1, T≤4	±15% or ±0.6mm, whicever is the greater(取较大者)	L≤6M	+5/0
				T2	±12.5% or ±0.4mm, whicever is the greater(取较大者)
	219.1≤D≤610 (D1)	±1.5% or ±0.75mm, whicever is the greater (取较大者)		T≤0.05D	+22.5%/-15%	6≤12	+10/0
				T1, 0.05D≤0.09D	±15% or ±0.6mm, whicever is the greater(取较大者)
				T2, T>0.09D	±12.5% or ±0.4mm, whicever is the greater(取较大者)	L>12	+by agreement/0
EN 10216-5 CFD	D3(D≤219.1)	±0.75% or ±0.3mm, whicever is the greater(取较大者)		T3	±10% or ±0.2mm, whicever is the greater(取较大者)
	D4(D≤219.1)	±0.5% or ±0.mm, whicever is the greater(取较大者)		T4	±7.5% or ±0.15mm, whicever is the greater(取较大者)
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≤3.8	+35%/0
		+0.4/-1.6		D<100,3.8≤4.6	+33%/0
				D<100,S>4.6	+28%/0
	100≤200	+0.4/-1.2		D>100, 2.4≤3.8	+35%/0
	200≤225	+0.4/-1.6		D>100,3.8≤4.6	+33%/0
				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	±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≤200	+0.38/-0.64
	200≤225	+0.38/-1.14
ASTM A269	D≤13	±0.13		D≤13	±15%	D<38	+3.2/0
	13	±0.13		13	±10%
	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					+5.0/0
	140-200	±0.75		For CD SMLS pipe D>38.1	+22%/0
	200-300	±1.25

Common Industrial Applications

Chemical and Petrochemical

Process and transfer line tubing
Heat exchanger and condenser tubes
Chloride-bearing process service

Marine and Offshore

Seawater cooling and ballast systems
Deck and process utility tubing
Offshore platform pipework

Food and Pharmaceutical

Hygienic process and transfer tubing
CIP and SIP system pipework
Purified water and clean-steam lines

Pulp, Paper and Water Treatment

Digester and bleach plant tubing
Black liquor and chemical recovery lines
Effluent and water treatment piping

Quality Assurance and Manufacturing Process

Certification and Documentation

All TP316 tubes are supplied to ASTM A213 / A269 / A312 with EN 10204 3.1 mill test certificates. PMI reports, NACE MR0175 / ISO 15156 compliance and full heat-number traceability are available on request.

Non-Destructive Testing (NDT)

Hydrostatic or eddy-current testing is performed on 100% of tubes. Ultrasonic testing and dye-penetrant inspection are available for critical chloride and pressure service.

Mechanical and Metallurgical Testing

Tensile, yield, elongation and hardness tests are carried out per heat, together with intergranular corrosion testing per ASTM A262 and microstructure examination where specified.

Dimensional and Surface Inspection

Outside diameter, wall thickness, ovality and straightness are verified against ASTM A1016 / A1016M, with surface finish inspected for hygienic and high-purity service.

TP316 vs TP304 / TP316L – Technical Comparison

TP316 adds around 2–3% molybdenum to the 18-8 austenitic base, which raises pitting resistance and extends service into chloride-bearing and reducing-acid environments. TP316L is the low-carbon variant, and TP304 is the molybdenum-free parent grade.

Chemical Composition

Molybdenum: TP316 2.00–3.00 % vs none in TP304
Carbon: TP316 ≤ 0.080 %, TP316L ≤ 0.030 %, TP304 ≤ 0.080 %
Nickel: TP316 10.0–14.0 %, TP316L 10.0–14.0 %, TP304 8.0–10.5 %
Chromium: TP316 16.0–18.0 %, TP304 18.0–20.0 %

Corrosion Performance

PREN: TP316 ≈ 24–26, TP304 ≈ 18–19
TP316 resists chloride pitting and crevice corrosion far better than TP304
TP316 tolerates reducing acids such as sulphuric and phosphoric acid
TP316 shows markedly better seawater and marine atmospheric performance

Mechanical Properties

Tensile strength: TP316 ≥ 515 MPa, TP316L ≥ 485 MPa, TP304 ≥ 515 MPa
Yield strength (0.2 %): TP316 ≥ 205 MPa, TP316L ≥ 170 MPa
Elongation: all grades ≥ 35 %
TP316L is preferred where welded joints will not be post-weld annealed

Selection Guidance

Choose TP316 for chlorides, seawater, reducing acids and pharmaceutical duty
Choose TP316L for welded heavy sections in the same service
Choose TP304 only for mildly corrosive, oxidising or food-grade duty where the molybdenum premium cannot be justified

Frequently Asked Questions

What is TP316 stainless steel tube?

TP316 (UNS S31600 / W.Nr. 1.4401) is a molybdenum-bearing austenitic stainless steel containing 2.00–3.00 % molybdenum. The molybdenum addition raises the pitting resistance equivalent number to roughly 24–26 and gives the grade markedly better resistance to chloride pitting, crevice corrosion and reducing acids than the 304 family.

What is the difference between TP316 and TP316L?

TP316L limits carbon to 0.030 % maximum against 0.080 % for TP316. The lower carbon content prevents chromium carbide precipitation in the heat-affected zone during welding, so TP316L resists intergranular corrosion after welding without post-weld solution annealing. TP316 offers slightly higher annealed yield strength at 205 MPa against 170 MPa.

Is TP316 suitable for seawater service?

TP316 is a significant improvement on TP304 in seawater and chloride-bearing service, but it is not immune to pitting, crevice attack or chloride stress corrosion cracking at elevated temperature. For continuous seawater contact or higher chloride levels, super duplex or 6 % molybdenum grades are normally specified instead.

What industries use TP316 seamless tubes?

TP316 is widely used in chemical and petrochemical processing, marine and offshore engineering, food and beverage, pharmaceuticals, pulp and paper, and water treatment. It is the default choice wherever chlorides or reducing acids are present and a higher alloy cannot be justified on cost.

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