Stainless Steel Seamless Pipes Supplier & Exporter
Metinox Overseas is a leading manufacturer and supplier of stainless steel seamless pipes - produced without a weld seam for uniform wall strength and superior pressure integrity. Our SS seamless pipes are available in austenitic, duplex, and super duplex grades, manufactured to ASTM A312, ASTM A213, and ASTM A269 standards. As a trusted seamless tube manufacturer in India, we supply stainless seamless pipes for oil & gas, chemical, pharmaceutical, power, and food industries across 40+ countries. From SS 304 seamless pipe to stainless steel 316 pipes and specialty grades, every SMLS pipe is supplied with full mill test certification and third-party inspection options.
Request a quote now!Table of Contents
- Types of Stainless Steel Seamless Pipes
- Available Grades for Stainless Steel Seamless Pipes
- Sizes, Schedules & Standards of Stainless Steel Seamless Pipes
- Applications of Stainless Steel Seamless Pipes
- FAQs About Stainless Steel Seamless Pipes
- Related Products
- Request Price for Stainless Steel Seamless Pipes
Types of Stainless Steel Seamless Pipes
We manufacture and supply all major types of SS seamless pipes and stainless seamless steel pipes, each suited to specific pressure, temperature, and corrosion requirements. All types are available in multiple grades and schedules with full ASTM / ASME certification.
Stainless Steel 304 Seamless Pipes
Stainless Steel 304L Seamless Pipes
Stainless Steel 304H Seamless Pipes
Stainless Steel 310S Seamless Pipes
Stainless Steel 310H Seamless Pipes
Stainless Steel 316/316L Seamless Pipes
Stainless Steel 316H Seamless Pipes
Stainless Steel 316Ti Seamless Pipes
Stainless Steel 317/317L Seamless Pipes
Stainless Steel 321/321H Seamless Pipes
Stainless Steel 347/347H Seamless Pipes
Stainless Steel 904L Seamless Pipes
Hot-Finished Stainless Steel Seamless Pipes
Hot-finished stainless seamless pipes are produced by heating a solid stainless steel billet to high temperatures and extruding or piercing it over a mandrel to form the hollow pipe shape. The resulting pipe is then hot-rolled to final dimensions and solution-annealed.
Cold-Drawn Stainless Steel Seamless Pipes
Cold-drawn SS pipe seamless variants are produced by drawing a hot-finished or extruded tube through a die at room temperature, achieving tighter dimensional tolerances, a smoother internal bore, and improved mechanical properties through work hardening.
SS 304 Seamless Pipes
SS 304 seamless pipe is the most widely specified stainless steel seamless pipe globally. Classified as an 18/8 austenitic grade (18% Cr, 8% Ni), it offers excellent general corrosion resistance, easy weldability, and broad chemical compatibility - making it the standard choice for food processing, dairy, pharmaceutical, and general industrial systems.
SS 316 / 316L Seamless Pipes
Stainless steel 316 pipes in seamless construction add 2-3% molybdenum to the 18/8 base alloy, providing significantly enhanced pitting and crevice corrosion resistance in chloride-bearing environments. Stainless 316 pipe is the standard specification for marine, offshore, pharmaceutical, and chemical process applications. The low-carbon 316L variant is specified where welding is involved.
SS 310 / 310S Seamless Pipes
Stainless steel 310 pipe is a high-chromium (25%), high-nickel (20%) austenitic grade engineered for extreme high-temperature service and oxidation resistance up to 1100C. Also referred to as SS 310 pipe, it is used in furnaces, kilns, heat-treatment equipment, and high-temperature chemical reactors where standard 304 and 316 grades would fail.
SS SMLS Pipes (General Category)
SMLS pipe - short for seamless pipe - is the standard trade term used across the global procurement and piping industry to specify any pipe produced without a weld seam. Metinox supplies SS SMLS pipe across all standard austenitic, duplex, and super duplex grades. All SS smls pipes are solution-annealed and pickled as standard, with hydrostatic and NDE testing per ASTM A312.
Seamless Stainless Steel Tubing (General Service & Instrumentation)
In addition to schedule pipes, Metinox supplies seamless stainless steel tubing for instrumentation, heat exchangers, condensers, and general corrosive service. Our ss seamless tube range covers small-diameter precision-drawn tubes with tight OD and wall tolerances, supplied per ASTM A269 and ASTM A213.
Grades: SS 304, 316, 316L, 321, 347
Standard: ASTM A269 | ASTM A213 | ASME SA213
Size range: 3 mm OD to 168 mm OD | 0.5 mm to 15 mm wall
Available Grades for Stainless Steel Seamless Pipes
Metinox stocks and supplies stainless steel seamless pipes and stainless seamless steel pipe across all major austenitic, duplex, super duplex, and high-alloy grades. Below is the full grade reference with chemical composition data.
Chemical Composition of ASTM A312 Seamless Pipe Grades
| Grade | UNS No. | C % Max | Mn % Max | Si % Max | Cr % | Ni % | Mo % | Other |
|---|---|---|---|---|---|---|---|---|
| TP304 | S30400 | 0.08 | 2.00 | 0.75 | 18.0-20.0 | 8.0-11.0 | - | - |
| TP304L | S30403 | 0.035 | 2.00 | 0.75 | 18.0-20.0 | 8.0-13.0 | - | - |
| TP304H | S30409 | 0.04-0.10 | 2.00 | 0.75 | 18.0-20.0 | 8.0-11.0 | - | - |
| TP316 | S31600 | 0.08 | 2.00 | 0.75 | 16.0-18.0 | 10.0-14.0 | 2.0-3.0 | - |
| TP316L | S31603 | 0.035 | 2.00 | 0.75 | 16.0-18.0 | 10.0-14.0 | 2.0-3.0 | - |
| TP316H | S31609 | 0.04-0.10 | 2.00 | 0.75 | 16.0-18.0 | 10.0-14.0 | 2.0-3.0 | - |
| TP317L | S31703 | 0.035 | 2.00 | 0.75 | 18.0-20.0 | 11.0-15.0 | 3.0-4.0 | - |
| TP321 | S32100 | 0.08 | 2.00 | 0.75 | 17.0-19.0 | 9.0-12.0 | - | Ti >= 5xC |
| TP321H | S32109 | 0.04-0.10 | 2.00 | 0.75 | 17.0-19.0 | 9.0-12.0 | - | Ti >= 4xC |
| TP347 | S34700 | 0.08 | 2.00 | 0.75 | 17.0-19.0 | 9.0-13.0 | - | Nb+Ta >= 10xC |
| TP347H | S34709 | 0.04-0.10 | 2.00 | 0.75 | 17.0-19.0 | 9.0-13.0 | - | Nb+Ta >= 8xC |
| TP310S | S31008 | 0.08 | 2.00 | 1.50 | 24.0-26.0 | 19.0-22.0 | - | - |
| Duplex 2205 | S32205 | 0.030 | 2.00 | 1.00 | 21.0-23.0 | 4.5-6.5 | 2.5-3.5 | N 0.08-0.20 |
| Super Duplex 2507 | S32750 | 0.030 | 1.20 | 0.80 | 24.0-26.0 | 6.0-8.0 | 3.0-5.0 | N 0.24-0.32 |
| 904L | N08904 | 0.020 | 2.00 | 1.00 | 19.0-23.0 | 23.0-28.0 | 4.0-5.0 | Cu 1.0-2.0 |
Mechanical Properties of ASTM A312 Seamless Grades
| Grade | Tensile Strength Min (MPa) | Yield Strength Min (MPa) | Elongation Min % | Hardness Max |
|---|---|---|---|---|
| TP304 / TP304L | 515 | 205 | 35 | 92 HRB |
| TP304H | 515 | 205 | 35 | 92 HRB |
| TP316 / TP316L | 515 | 205 | 35 | 92 HRB |
| TP316H | 515 | 205 | 35 | 92 HRB |
| TP317L | 515 | 205 | 35 | 95 HRB |
| TP321 / TP321H | 515 | 205 | 35 | 92 HRB |
| TP347 / TP347H | 515 | 205 | 35 | 92 HRB |
| TP310S | 515 | 205 | 35 | 95 HRB |
| Duplex 2205 | 620 | 450 | 25 | 31 HRC |
| Super Duplex 2507 | 795 | 550 | 15 | 32 HRC |
Sizes, Schedules & Standards of Stainless Steel Seamless Pipes
All Metinox stainless steel seamless pipes and SS smls pipes conform to ASTM A312 / ASME SA312 dimensional requirements per ANSI / ASME B36.19M. Mill test certificates to EN 10204 3.1 are standard; 3.2 (third-party witnessed) available on request.
Standards Reference Table
| Standard | Full Title | Pipe Type | Key Grades |
|---|---|---|---|
| ASTM A312 / ASME SA312 | Seamless, Welded & Cold-Worked Austenitic SS Pipes | SMLS & WLD | TP304, TP316, TP321, TP347, TP310S |
| ASTM A213 / ASME SA213 | Seamless Ferritic & Austenitic Alloy-Steel Boiler & HE Tubes | Seamless Tubes | T304, T316, T321, T347 |
| ASTM A269 / ASME SA269 | Seamless & Welded Austenitic SS Tubing - General Service | Seamless Tubes | 304, 316, 321 |
| ASTM A789 / ASME SA789 | Seamless & Welded Duplex SS Tubing | Seamless | S31803, S32205, S32750 |
| ASTM A790 / ASME SA790 | Seamless & Welded Duplex SS Pipes | Seamless | S31803, S32205, S32750 |
| DIN EN 10216-5 | Seamless Steel Tubes for Pressure Purposes - SS | Seamless | 1.4301, 1.4401, 1.4571 |
| JIS G3459 | SS Pipes | Seamless | SUS304, SUS316, SUS321 |
| BS 3605 | Seamless & Welded SS Pipes for Pressure Service | Seamless | 304S31, 316S31 |
ASTM A312 Seamless Pipe - Size & Wall Thickness Table (ANSI B36.19M)
| NPS (inch) | OD (mm) | SCH 5S Wall (mm) | SCH 10S Wall (mm) | SCH 40S Wall (mm) | SCH 80S Wall (mm) | SCH 160 Wall (mm) | XXS Wall (mm) |
|---|---|---|---|---|---|---|---|
| 1/8" | 10.29 | 1.24 | 1.73 | 2.41 | 3.02 | - | - |
| 1/4" | 13.72 | 1.65 | 2.24 | 3.02 | 3.02 | - | - |
| 1/2" | 21.34 | 1.65 | 2.11 | 2.77 | 3.73 | 4.78 | 7.47 |
| 3/4" | 26.67 | 1.65 | 2.11 | 2.87 | 3.91 | 6.35 | 7.82 |
| 1" | 33.40 | 1.65 | 2.77 | 3.38 | 4.55 | 6.35 | 9.09 |
| 1 1/2" | 48.26 | 1.65 | 2.77 | 3.68 | 5.08 | 7.14 | 10.16 |
| 2" | 60.33 | 1.65 | 2.77 | 3.91 | 5.54 | 8.74 | 11.07 |
| 2 1/2" | 73.03 | 2.11 | 3.05 | 5.16 | 7.01 | 9.53 | 14.02 |
| 3" | 88.90 | 2.11 | 3.05 | 5.49 | 7.62 | 11.13 | 15.24 |
| 4" | 114.30 | 2.11 | 3.05 | 6.02 | 8.56 | 13.49 | 17.12 |
| 6" | 168.28 | 2.77 | 3.40 | 7.11 | 10.97 | 18.26 | 21.95 |
| 8" | 219.08 | 2.77 | 3.76 | 8.18 | 12.70 | 23.01 | 22.23 |
| 10" | 273.05 | 3.40 | 4.19 | 9.27 | 12.70 | 28.58 | 25.40 |
| 12" | 323.85 | 3.96 | 4.57 | 9.53 | 12.70 | 25.40 | 25.40 |
| 14" | 355.60 | 3.96 | 6.35 | 9.53 | 12.70 | - | - |
| 16" | 406.40 | 4.19 | 6.35 | 9.53 | 12.70 | - | - |
| 18" | 457.20 | 4.19 | 6.35 | 9.53 | 12.70 | - | - |
| 20" | 508.00 | 4.78 | 6.35 | 9.53 | 12.70 | - | - |
| 24" | 609.60 | 6.35 | 6.35 | 9.53 | - | - | - |
Full dimensional data per ANSI/ASME B36.19M. Custom sizes available on inquiry.
Tolerance of ASTM A312 Seamless Pipes
| Parameter | Tolerance |
|---|---|
| Outside Diameter (NPS <= 1 1/2") | +- 0.4 mm |
| Outside Diameter (NPS > 1 1/2") | +- 0.75% |
| Wall Thickness (all sizes) | -12.5% of nominal |
| Length (SRL: 4.8-7.3 m) | As agreed |
| Length (DRL: 8.5-14.6 m) | As agreed |
| Straightness | 1.5 mm per 1.5 m |
Standard Lengths
| Length Type | Range |
|---|---|
| Single Random Length (SRL) | 4.8 m - 7.3 m (16 ft - 24 ft) |
| Double Random Length (DRL) | 8.5 m - 14.6 m (28 ft - 48 ft) |
| Cut-to-Length (CTL) | Any specified length; min. 100 mm |
Applications of Stainless Steel Seamless Pipes
Our stainless steel seamless pipes and SS smls pipes are specified across the most demanding industrial sectors globally. Seamless construction is mandatory or strongly preferred in the following applications.
Oil & Gas: Seamless SS 316L and duplex 2205 pipes for wellhead trees, Christmas tree assemblies, process headers, gas treatment, and refinery heat-exchanger circuits. Sour service material is supplied in compliance with NACE.
Chemical and Petrochemical Processing: Seamless 316L, 317L and 904L pipes used in reactors, distillation columns, heat exchangers, chemical transfer headers and corrosive-media process lines.
Pharmaceutical / Biotechnology: Electropolished TP316L seamless pipes are used for WFI distribution, clean steam, CIP/SIP, bioreactors and cleanroom utility piping, in compliance with FDA 21 CFR and EU GMP Annex 1.
Power Generation: ASTM A312 TP321 and TP347 seamless pipes and ASTM A213 T321/T347 tubes are supplied for boiler, superheater, and critical thermal and nuclear service.
Food & Beverage Processing: Non-porous 304 and 316L seamless pipes are used in dairy processing systems, brewing circuits, CIP sanitary loops, and beverage manufacturing lines.
Aerospace & Defence: Seamless TP321 and TP347 pipes are used in aircraft engine exhaust manifolds, hydraulic systems, and high-temperature fuel-line assemblies.
Marine and Offshore: Super duplex 2507 seamless pipes are supplied for seawater lift pumps, injection headers, topside process piping and firewater mains on offshore facilities.
Desalination & Water Treatment: Duplex 2205 and super duplex 2507 seamless pipes are used in reverse osmosis pressure vessels, brine headers and multi-stage flash systems.
Pulp, Paper and Chemical Plants: Seamless 904L and 317L pipes are selected for bleach plant headers, digesters and process lines handling sulphuric, hydrochloric and organic acids.
Construction & Architecture: Cold-drawn seamless 304 and 316 round pipes are used in structural columns, frameworks, balustrade posts, and architectural feature elements requiring uniform wall thickness and superior finish.
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FAQs About Stainless Steel Pipe
The extrusion of a solid billet produces a stainless steel seamless pipe with no optimal weld seam and provides a constant strength of the wall. It is used when high-pressure and high-temperature, and critical industrial service is required with no permissible risk of weld-zone failure.
SS 304 non-perforated pipe is used in a general, food and pharma service. SS 316 smooth pipe includes 2-3% molybdenum to enhance chloride and pitting resistance - which is required in marine, offshore, and chemical processes that deal with saline or acidic service.
The main standard of austenitic SS seamless pipes is the ASTM A312 that includes grades TP304, TP316, TP321, TP347 between the NPS 1/8 of an inch to 30. EN 10204 3.1 mill test certificates are standard on all Metinox seamless pipes on an order basis.
SS seamless pipes are commonly found in oil and gas production, chemical processing, pharmaceuticals, power generation, food and beverage, marine, and aerospace (wherever high pressure, elevated temperature, or corrosive media necessitate uniformity in the integrity of the pipe walls) these seamless pipes are common.
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