TP316L Seamless Stainless Steel Tube

UNS S31603 | 1.4404 | ASTM A213

TP316L Seamless Stainless Steel Tube (S31603 / 1.4404) 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 TP316L Tube?

Seamless TP316L (UNS S31603 / W.Nr. 1.4404) tube is the low-carbon version of the molybdenum-bearing 316 grade. By limiting carbon to 0.030% maximum it prevents chromium carbide precipitation during welding, so the molybdenum-rich corrosion resistance of the 316 family is preserved in the heat-affected zone as well as in the parent metal.

TP316L Stainless Steel Seamless Tube(UNS S31603) is an extra-low carbon, molybdenum-alloyed austenitic stainless steel tubing engineered for high-purity, high-pressure, and corrosion-critical applications.

Produced from a solid billet via seamless extrusion, these tubes deliver a uniform metallurgical structure, eliminating weld seam defects and ensuring consistent mechanical performance and superior structural integrity along the entire length.

The defining characteristic of Grade 316L is its maximum carbon content of 0.03%, which effectively prevents sensitization—the precipitation of chromium carbides at grain boundaries during welding. This ensures that the heat-affected zone (HAZ) maintains the same corrosion resistance as the base metal, eliminating the need for post-weld solution annealing in most applications.

TP316L Key Features and Technical Advantages

The ultra-low carbon composition minimizes the risk of intergranular corrosion (IGC), commonly referred to as “weld decay,” making TP316L the preferred choice for welded systems.

With 2.0% – 3.0% molybdenum (Mo), TP316L offers excellent resistance to chloride-induced corrosion, outperforming TP304/304L in marine and chemical environments.

The absence of longitudinal weld seams ensures uniform wall thickness, improved fatigue resistance, and higher allowable stress values under pressure service conditions.

Feature	Description
Exceptional Post-Weld Corrosion Resistance	The ultra-low carbon composition minimizes the risk of intergranular corrosion (IGC), commonly referred to as “weld decay,” making TP316L the preferred choice for welded systems.
Superior Resistance to Pitting and Crevice Corrosion	With 2.0% – 3.0% molybdenum (Mo), TP316L offers excellent resistance to chloride-induced corrosion, outperforming TP304/304L in marine and chemical environments.
High-Precision Seamless Construction	The absence of longitudinal weld seams ensures uniform wall thickness, improved fatigue resistance, and higher allowable stress values under pressure service conditions.
Excellent Formability and Fabrication	High ductility allows for bending, flaring, and complex fabrication, while maintaining structural integrity and corrosion resistance.
Hygienic Surface and Cleanability	Smooth, non-porous internal surfaces meet sanitary and high-purity requirements, compliant with ASME BPE standards for pharmaceutical and food-grade systems.

TP316L Product Specifications and Data

To provide a comprehensive overview of this versatile material, here are the detailed technical specifications and performance data for 316L stainless steel.

The key difference in 316L's composition is its significantly lower carbon content (max 0.03%), while retaining the essential molybdenum for superior corrosion resistance.

Table 1: Chemical Composition of 316L Stainless Steel

Cr	Ni	Mo	P	S	Mn	Si	C
16.00−18.00	10.00−14.00	2.00−3.00	≤0.045	≤0.03	≤2.00	≤1.00	≤0.035

Grade 316L offers a good balance of strength and ductility, with a slightly lower tensile and yield strength compared to 316 due to its lower carbon content, but still robust for most demanding applications.

Table 2: Typical Mechanical Properties of 316L Stainless Steel

Tensile Strength	Yield Strength	Elongation	Rockwell Hardness	Brinell Hardness
485−690 MPa	≥170 MPa	≥ 35%	≤90 HRB	≤192 HB

These physical properties are largely similar to 316, indicating consistent thermal and electrical behavior.

Table 3: Typical Physical Properties of 316L Stainless Steel

Density	Melting Point	Thermal Expansion	Thermal Conductivity	Modulus of Elasticity	Electrical Resistivity
8.0 g/cm3	1370−1400 ∘C	16.5 μm/m⋅∘C (20−100∘C)	16.3 W/m⋅K (100∘C)	193 GPa	7.4×10−7 Ω⋅m (20∘C)

TP316L Dimensional Standards and Tolerances

TP316L seamless tubes are supplied 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
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≤12	+10/0
				T1, 0.05D≤0.09D	±15% or ±0.6mm, whicever is the greater	6≤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≤3.8	+35%/0
		+0.4/-1.6		D＜100,3.8≤4.6	+33%/0
		+0.4/-1.6		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
	200≤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	±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%	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

TP316L Common Industrial Applications

Industry	Typical Applications
Pharmaceutical and Biotechnology	WFI and purified water distribution tubing Clean-steam and CIP system piping Aseptic process transfer lines
Chemical and Petrochemical	Process and transfer line tubing Heat exchanger and condenser tubes Chloride and reducing-acid service
Offshore, Oil and Gas	Seawater and process utility tubing Instrumentation and impulse lines Corrosive service transfer pipework
Heat Exchangers, Precision and Transport	Heat exchanger and condenser tube banks Precision instrumentation and sensor housings Automotive and aerospace component tubing

TP316L Quality Assurance and Production Process

Process Step	Description
Certification and Documentation	All TP316L tubes are supplied to ASTM A213 / A269 / A312 with EN 10204 3.1 mill test certificates. NACE MR0175 / ISO 15156 compliance, PMI reports 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 can be supplied for critical service, with records retained for each production lot.
Metallurgical Verification	Low-carbon chemistry, ferrite content and microstructure are verified per heat. Intergranular corrosion testing per ASTM A262 Practice E is available for post-weld and sensitisation-critical applications.
Mechanical Testing	Tensile, yield, elongation and hardness tests are carried out per heat. Impact and flattening tests can be supplied for low-temperature and pressure-critical service.

TP316L vs TP316 / TP304L – Technical Comparison

TP316L and TP316 are the same molybdenum-bearing austenitic grade, separated only by carbon content and the welding behaviour that follows from it. TP304L is the molybdenum-free low-carbon counterpart.

Chemical Composition

Carbon: TP316L ≤ 0.030 % vs TP316 ≤ 0.080 %
Molybdenum: TP316L 2.00–3.00 %, TP316 2.00–3.00 %, TP304L none
Nickel: TP316L 10.0–14.0 %, TP316 10.0–14.0 %, TP304L 8.0–12.0 %
Chromium: TP316L 16.0–18.0 %, TP304L 18.0–20.0 %

Corrosion Performance

PREN: TP316L ≈ 24–26 vs TP304L ≈ 18–19
TP316L preserves pitting and crevice corrosion resistance in the heat-affected zone after welding
TP304L resists intergranular corrosion after welding but remains limited in chlorides
Neither grade is immune to chloride stress corrosion cracking

Mechanical Properties

Tensile strength: TP316L ≥ 485 MPa, TP316 ≥ 515 MPa, TP304L ≥ 485 MPa
Yield strength (0.2 %): TP316L ≥ 170 MPa, TP316 ≥ 205 MPa
Elongation: all grades ≥ 35 %
TP316 and TP304 offer higher annealed strength than their L variants

Selection Guidance

Choose TP316L for welded chloride-bearing service that cannot be post-weld annealed — the default choice for process tubing
Choose TP316 where maximum annealed strength is required and welding is light or followed by annealing
Choose TP304L only in molybdenum-free, mildly corrosive duty

Frequently Asked Questions About TP316L Seamless Stainless Steel Tubes

What is TP316L stainless steel tube?

TP316L (UNS S31603 / W.Nr. 1.4404) is the low-carbon version of the molybdenum-bearing 316 grade, containing 2.00–3.00 % molybdenum and a maximum of 0.030 % carbon. It provides the same chloride and reducing-acid resistance as TP316 while resisting intergranular corrosion in the heat-affected zone after welding.

What is the difference between TP316 and TP316L?

The only significant difference is carbon content: 0.030 % maximum for TP316L against 0.080 % for TP316. That makes TP316L the preferred grade for welded assemblies and heavy sections that will not be post-weld annealed. TP316 retains higher annealed yield strength at 205 MPa against 170 MPa for TP316L.

Is TP316L better than TP304L?

For chloride-bearing, reducing-acid or marine service, yes — the 2.00–3.00 % molybdenum raises the pitting resistance equivalent number from roughly 18–19 to 24–26. For mildly corrosive, oxidising or food-grade service where molybdenum is not required, TP304L is equally suitable and more economical.

Which standards cover TP316L seamless tubes?

TP316L seamless tubing is normally supplied to ASTM A213 / A213M, ASTM A269 and ASTM A312, with dimensional inspection per ASTM A1016 / A1016M. Equivalent European specifications include EN 10216-5 grade 1.4404.

Request a TP316L Tube Quotation

Send your TP316L tube enquiry with application, medium, size (OD and wall thickness or schedule), quantity, length, end finish and inspection requirements.

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