Seamless Stainless Steel TP316H Pipe
What is a Seamless Stainless Steel TP316H Pipe?
Seamless Stainless Steel TP316H Pipe is the high-carbon, high-temperature variant of 316 molybdenum-bearing austenitic stainless steel, made from a solid billet without a welded seam. The controlled carbon range of 0.04–0.10 %, combined with 2–3 % molybdenum, provides elevated-temperature strength together with enhanced corrosion resistance.
The molybdenum addition gives the 316 family significantly better resistance to pitting and crevice corrosion in chloride environments than standard 304, while the H-carbon control delivers the creep and stress-rupture strength needed for pressure parts operating continuously above about 500 °C.
Produced to ASTM A312, A213 and A269 (ASME equivalents included) with a minimum 1040 °C solution anneal, TP316H seamless pipe is specified for superheaters, heat-exchanger shells and chemical reactor piping where both heat and corrosive media are present.
Stainless Steel TP316H vs TP316 vs TP316L vs TP316Ti: Choosing Inside the 316 Family
The 316 family shares a 16-18 % chromium, 10-14 % nickel, 2-3 % molybdenum base; the variants differ in carbon control and stabilization. The right pick depends on both temperature and corrosive environment.
| Grade | Key Chemistry / Condition | Where It Fits |
|---|---|---|
| TP316 | C ≤ 0.08 % | General chloride-resistant service |
| TP316L | C ≤ 0.03 % | As-welded equipment in corrosive media; lower high-temperature strength |
| TP316H | C 0.04-0.10 %, grain size control | Creep strength for boilers, superheaters and pressure parts above 500 °C with molybdenum pitting resistance |
| TP316Ti | Ti stabilized | Resists sensitization during slow cooling and repeated thermal cycles |
Product Specifications
Specification data for Seamless Stainless Steel TP316H Pipe is compiled from the governing ASTM/ASME/EN standards and our routine production records; typical values are shown where a standard leaves a limit open.
| Category | Standard / Designation |
|---|---|
| Seamless Pipe | ASTM A312 / ASME SA312 |
| Seamless & Welded Tube | ASTM A213 / A269 / ASME SA213 / SA269 |
| UNS Designation | S31609 |
| Werkstoff Number | 1.4436 (H-modified) |
| EN Designation | X5CrNiMo17-12-2 (H-modified) |
Size and Weight Chart
| NPS | OD (mm) | SCH 40 WT (mm) | SCH 40 kg/m | SCH 80 WT (mm) | SCH 80 kg/m |
|---|---|---|---|---|---|
| 1/4" | 13.7 | 2.24 | 0.65 | 3.02 | 0.81 |
| 1/2" | 21.3 | 2.77 | 1.29 | 3.73 | 1.65 |
| 3/4" | 26.7 | 2.87 | 1.72 | 3.91 | 2.24 |
| 1" | 33.4 | 3.38 | 2.55 | 4.55 | 3.3 |
| 1-1/4" | 42.2 | 3.56 | 3.46 | 4.85 | 4.55 |
| 1-1/2" | 48.3 | 3.68 | 4.13 | 5.08 | 5.52 |
| 2" | 60.3 | 3.91 | 5.54 | 5.54 | 7.62 |
| 3" | 88.9 | 5.49 | 11.51 | 7.62 | 15.57 |
| 4" | 114.3 | 6.02 | 16.38 | 8.56 | 22.75 |
| 6" | 168.3 | 7.11 | 28.8 | 10.97 | 43.38 |
| 8" | 219.1 | 8.18 | 43.36 | 12.7 | 65.88 |
Weights are theoretical for seamless pipe (kg per metre) calculated from the nominal dimensions; actual weights vary within the dimensional tolerances shown below. Intermediate sizes and schedules between SCH 10S and SCH 160 are produced to order.
Chemical Composition
| Element | Min (%) | Max (%) |
|---|---|---|
| Carbon (C) | 0.04 | 0.10 |
| Manganese (Mn) | — | 2.00 |
| Silicon (Si) | — | 0.75 |
| Phosphorus (P) | — | 0.045 |
| Sulfur (S) | — | 0.030 |
| Chromium (Cr) | 16.00 | 18.00 |
| Nickel (Ni) | 11.00 | 14.00 |
| Molybdenum (Mo) | 2.00 | 3.00 |
| Iron (Fe) | Balance | — |
Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength, min | 515 MPa (75 ksi) |
| Yield Strength (0.2 % offset), min | 205 MPa (30 ksi) |
| Elongation in 2 in. / 50 mm, min | 35 % |
| Hardness (typical, annealed) | ≤ 201 HBW |
| Heat Treatment | Solution annealed, min 1040 °C, rapid cooling |
Physical Properties
| Property | Value |
|---|---|
| Density | 8.00 g/cm³ |
| Melting Range | 1370 – 1400 °C |
| Elastic Modulus | 193 GPa |
| Coefficient of Thermal Expansion (0–100 °C) | 15.9 µm/m·°C |
| Thermal Conductivity (at 100 °C) | 16.3 W/m·K |
| Specific Heat Capacity | 500 J/kg·K |
| Electrical Resistivity | 74 µΩ·cm |
Equivalent Grades
| Standard System | Designation |
|---|---|
| UNS | S31609 |
| Werkstoff Nr. | 1.4919 |
| EN | X6CrNiMo17-12-2 (H) |
| JIS | SUS 316H equivalent |
Why TP316H Combines Creep Strength with Chloride Resistance
TP316H is effectively two grades in one. The H-carbon control and grain-size requirement deliver the elevated-temperature creep and rupture strength needed for code-stamped boilers, superheaters and pressure piping, while the 2-3 % molybdenum addition preserves the pitting and crevice corrosion resistance that distinguishes the 316 family from plain 304 grades. Where a high-temperature line also touches chloride-bearing condensate or process media, 316H removes the need for a material change along the circuit.
The seamless route completes the package: no weld seam means no sensitized joint and no local weakness in exactly the high-temperature, corrosive conditions the grade is chosen for. We supply TP316H solution annealed at a minimum of 1040 °C with rapid cooling, certified to ASTM A312/A213 and their ASME equivalents.
Manufacturing Process
Our seamless production route for Seamless Stainless Steel TP316H Pipe follows these documented stages:
- Billet Selection & Inspection: Certified EAF/AOD-melted rounds are ultrasonically inspected for internal soundness before entering the mill.
- Hot Piercing & Extrusion: The solid billet is cross-roll pierced or hot extruded at about 1150-1200 °C to form a hollow shell, consolidating the structure without any weld seam.
- Cold Drawing / Pilgering: Successive cold-drawing or cold-pilgering passes reduce diameter and wall to final size with tight dimensional control.
- Intermediate Annealing: Stress-relief or intermediate anneals between passes restore ductility for further reduction.
- Solution Treatment: A final solution anneal (typically 1040-1100 °C for austenitic grades) followed by rapid quench dissolves carbides and restores the fully austenitic, corrosion-resistant structure.
- Pickling & Passivation: Scale is removed in an acid bath, leaving the uniform passive surface required for corrosion service.
- Straightening, Cutting & Testing: Pipes are straightened, cut to length, then verified by eddy-current/ultrasonic examination, hydrostatic pressure testing and full dimensional inspection.
Surface Finish Options
- Pickled & Annealed: Standard supply condition; uniform matte passive surface, ideal for further fabrication.
- Bright Annealed: Annealed in hydrogen atmosphere for a reflective, scale-free surface used in instrumentation and sanitary lines.
- Mechanically Polished: Grit 180-600 finishes for decorative and hygienic applications.
- Mirror Polished: A fully reflective finish for architectural and high-purity service.
Dimensional Tolerances
Delivered dimensions are verified against the tolerances below; tighter tolerances can be negotiated for instrumentation and precision applications.
| Dimension | Tolerance |
|---|---|
| OD, tube ≤ 25.4 mm (cold worked) | ± 0.10 mm |
| OD, tube 25.4 – 38.1 mm | ± 0.15 mm |
| OD, tube 38.1 – 50.8 mm | ± 0.20 mm |
| OD, hot-finished pipe ≥ 50.8 mm | ± 1 % of OD |
| Wall thickness | - 12.5 % under-tolerance (min-wall basis) |
| Straightness | ≤ 1 mm per metre |
| Cut length | + 10 / - 0 mm (fixed lengths) |
Common Industrial Applications
Because of its characteristic property profile, Seamless Stainless Steel TP316H Pipe is specified in the following industries and services:
- Chemical & Petrochemical Plants: Reactor piping, heat-exchanger tubing and transfer lines handling chloride-bearing or acidic media at temperature.
- Power Generation: Superheater and reheater tubing in plants firing corrosive fuels.
- Pulp & Paper Industry: Digesters and bleach-plant piping where chlorides and temperature combine.
- Pharmaceutical & Food Processing: Corrosion-resistant hygienic piping with elevated-temperature sterilization cycles.
- Marine & Coastal Installations: Piping exposed to salt-laden atmospheres where 304H would pit.
- Thermal Processing Equipment: Furnace cooling coils and quench systems requiring both heat and corrosion capability.
Quality Assurance, Testing and Documentation
Every length of Seamless Stainless Steel TP316H Pipe passes through a documented quality-control chain before dispatch:
- Material Certification: EN 10204 3.1 mill test certificates are issued for every heat; 3.2 certification with third-party witness (TUV, SGS, BV) is available on request.
- Chemical & Mechanical Testing: Heat-level chemical analysis plus tensile, hardness and, where applicable, flattening, flaring and reverse-flattening tests per the governing standard.
- Non-Destructive Examination: 100 % eddy-current or ultrasonic testing and hydrostatic or pneumatic pressure testing in line with the standard's supplementary requirements.
- Dimensional & Visual Inspection: Full OD, wall thickness, ovality and length verification with visual surface inspection after pickling or finishing.
- Traceability & Marking: Heat numbers stenciled or banded on every length, maintaining complete melt-to-pipe traceability.
Export and Packaging
Pipes are bundled with steel strapping and fitted with plastic or steel end caps, then packed in seaworthy wooden cases or crates and secured in containers for long-distance ocean freight. Standard export documentation — commercial invoice, packing list, certificate of origin, mill test certificates and, where required, third-party inspection reports — accompanies every shipment. Container-load and bulk project orders receive priority production slots and consolidated shipping documentation.
Frequently Asked Questions
Q1. When should TP316H be selected instead of 316L?
A: Choose 316H when the pipe will operate above roughly 500 °C and carry pressure — the higher carbon delivers the creep strength 316L lacks. Choose 316L when maximum corrosion resistance after welding is the priority.
Q2. Is TP316H suitable for seawater service?
A: It offers good resistance to coastal atmospheres and intermittent seawater exposure, but for continuous immersion or high-velocity seawater, super austenitic or duplex grades are recommended.
Q3. What is the intergranular corrosion behavior of 316H?
A: The H-grade is intended for high-temperature strength. Without post-weld solution annealing, welded 316H can be susceptible to sensitization in strongly corrosive media — a risk assessment against the actual environment is advised.
Q4. Can you supply third-party inspection for 316H pipe?
A: Yes. TÜV, SGS, BV or customer-designated inspectors can witness tensile, hardness, NDT and hydrostatic testing before shipment.
Ready to Request a Quotation?
Send us your size range, wall thickness/schedule, standard and quantity for Seamless Stainless Steel TP316H Pipe, and our engineering team will respond with a detailed technical and commercial offer within 24 hours. Custom sizes, third-party inspection and full export documentation are part of our standard service.
