S31603 Stainless Steel Seamless Tube

UNS S31603|1.4404|TP316L Seamless Stainless Steel Tube

UNS S31603|1.4404|TP316L Seamless Stainless Steel Tube
Seamless Stainless Steel TP316L Tubes (UNS S31603 / W.Nr. 1.4404) are premium-grade austenitic solutions engineered for maximum corrosion resistance and structural integrity in aggressive 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 extra-low carbon content (0.03% max) and strategic Molybdenum (2-3%) addition, our TP316L tubing effectively prevents carbide precipitation during welding, eliminating the risk of intergranular corrosion without the need for post-weld annealing. These tubes are indispensable for mission-critical applications in pharmaceutical processing, marine infrastructure, and high-pressure petrochemical systems. Through advanced cold-drawing and precise solution annealing, XinZhe ensures every tube maintains a stable microstructure and superior surface finish for demanding global industrial needs.

TP316L PREN ≈ 24-26,higher than TP304L PREN ≈ 18
Quantity:
Contact Now

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.

Manufactured 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.

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.

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.

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

CrNiMoPSMnSiC
16.00−18.0010.00−14.002.00−3.00≤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 StrengthYield StrengthElongationRockwell HardnessBrinell 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

DensityMelting PointThermal ExpansionThermal ConductivityModulus of ElasticityElectrical Resistivity
8.0 g/cm31370−1400 ∘C16.5 μm/m⋅∘C (20−100∘C)16.3 W/m⋅K (100∘C)193 GPa7.4×10−7 Ω⋅m (20∘C)

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 :

StandardOD(D)Tolerance（MM)Thickness(S)Tolerance(MM)LengthTolerance
MMCommon HighMMMM
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/-0.8D<100,S≤2.4+40%/0HFD, all size+5.0/0
+0.4/-1.2D<100,2.4≤3.8+35%/0
+0.4/-1.6D<100,3.8≤4.6+33%/0
D<100,S>4.6+28%/0
100≤200+0.4/-1.2D>100, 2.4≤3.8+35%/0
200≤225+0.4/-1.6D>100,3.8≤4.6+33%/0
D>100,S>4.6+28%/0
ASTM A213
CFD		D<25±0.10D≤38.1+20%/0CFD, D<50.8+3.0/0
25≤D≤40±0.15
40±0.20
50≤D<65±0.25
65≤D<75±0.30D>38.1+22%/0CFD, D≥50.8+5.0/0
75≤D≤100±0.38
100≤200+0.38/-0.64
200≤225+0.38/-1.14
ASTM A269D≤13±0.13D≤13±15%D<38+3.2/0
13±0.1313±10%
38≤D<89±0.25D>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 A270D<25±0.13For weld pipe all size±12.5%+3.0/0
25-50±0.20
50-75±0.25
75-100±0.38For CD SMLS pipe D≤38.1+20%/0
100-140±0.38+5.0/0
140-200±0.75For CD SMLS pipe D>38.1+22%/0
200-300±1.25

Common Industrial 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

Quality Assurance and Manufacturing Process

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

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.

Ready to Request a Quotation?

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

Request a TP316L Tube Quotation